CORONA - THE COMPLETE GUIDE - LEGRENZI STUDIO · 2020. 9. 20. · Francesco Legrenzi was born in...
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Corona Renderer THE COMPLETE GUIDE Francesco Legrenzi
Transcript of CORONA - THE COMPLETE GUIDE - LEGRENZI STUDIO · 2020. 9. 20. · Francesco Legrenzi was born in...
Corona Renderer THE COMPLETE GUIDE
Francesco Legrenzi
Corona Renderer
THE COMPLETE GUIDE First edition
Original title Corona Renderer - THE COMPLETE GUIDE by Francesco Legrenzi Copyright © 2020 Francesco Legrenzi Illustrations and layout Eng. Francesco Legrenzi www.francescolegrenzi.com First edition Second edition Third edition November 2020 The author is available to owners of rights with whom he has not been able to contact for any matter concerning involuntary omissions or mistakes in the citations of sources of the written and illustrated content herein. All rights reserved. No part of this book can be reproduced, stored in archive systems or transmitted in any form or medium, electronic, mechanical, photocopy, recording or other, without prior written permission from the author. The author of this volume is responsible for the preparation of this book, the author does not assume any responsibility, explicit or implicit, regarding any applications of the content of the book. Names and trademarks cited in this volume are generally registered by the respective publishing houses.
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1. INTRODUCTION ..................................................................................................... 1
1.1. GENERAL ............................................................................................................................................................................................... 1
1.1.1. Author information................................................................................................................................................................................................ 1
1.1.2. Acknowledgments ................................................................................................................................................................................................ 1
1.1.3. Preface ....................................................................................................................................................................................................................... 2
1.1.4. About the book ........................................................................................................................................................................................................ 3
1.1.5. Contents .................................................................................................................................................................................................................... 4
1.1.6. Get the most out of the book ........................................................................................................................................................................... 4
1.1.7. Corona Renderer and the hardware ............................................................................................................................................................ 5
1.1.8. User license .............................................................................................................................................................................................................6
1.1.9. The book’s website ............................................................................................................................................................................................... 7
1.1.10. THE DVDs .................................................................................................................................................................................................................. 7
2. CORONA RENDERER ............................................................................................ 9
2.1. CORONA RENDERER’S HISTORY ................................................................................................................................................. 9
2.1.1. Ondra’s College Years .........................................................................................................................................................................................9
2.1.2. First public interest .......................................................................................................................................................................................... 10
2.1.3. Corona Renderer v1.0 and the commercial version ........................................................................................................................ 14
2.1.4. Chaos Group merger ........................................................................................................................................................................................ 15
2.1.5. The philosophy of Corona Renderer, strengths and weaknesses .......................................................................................... 16
2.2. CORONA RENDERER INSTALLATION ........................................................................................................................................ 17
2.3. CORONA INTERFACE ..................................................................................................................................................................... 17
2.4. ORGANIZATION AND PURPOSE OF THE BOOK ..................................................................................................................... 22
3. CORONA - Scene TAB ..................................................................................... 23
3.1. GENERAL SETTINGS ...................................................................................................................................................................... 23
VFB - Show VFB ..................................................................................................................................................................................................... 24 3.1.1.
VFB - Post ................................................................................................................................................................................................................ 28 3.1.2.
VFB - Stats .............................................................................................................................................................................................................. 49 3.1.3.
VFB - History .......................................................................................................................................................................................................... 53 3.1.4.
VFB - DR ................................................................................................................................................................................................................... 54 3.1.5.
3.1.6. VFB - LightMix ....................................................................................................................................................................................................... 54
Interactive Rendering ..................................................................................................................................................................................... 59 3.1.7.
Corona Material Library ................................................................................................................................................................................. 61 3.1.8.
Reset settings ..................................................................................................................................................................................................... 63 3.1.9.
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3.1.10. Corona Image Editor...................................................................................................................................................................................... 64
Progressive rendering limits ...................................................................................................................................................................... 71 3.1.11.
3.1.12. Save/Resume rendering .............................................................................................................................................................................. 73
Render overrides ............................................................................................................................................................................................. 73 3.1.13.
Denoising ............................................................................................................................................................................................................. 76 3.1.14.
3.1.15. Render selected .............................................................................................................................................................................................. 82
3.2. SCENE ENVIRONMENT ................................................................................................................................................................ 83
4. CORONA - Camera TAB ................................................................................... 91
4.1. POSTPROCESSING ........................................................................................................................................................................ 91
4.1.1. Use simple exposure ....................................................................................................................................................................................... 92
4.1.2. Basic photographic settings ...................................................................................................................................................................... 92
4.1.3. LUT ........................................................................................................................................................................................................................... 102
4.1.4. Sharpening/Blurring ..................................................................................................................................................................................... 102
4.2. BLOOM AND GLARE .................................................................................................................................................................... 102
4.3. CAMERA ........................................................................................................................................................................................ 103
4.3.1. Depth of field ..................................................................................................................................................................................................... 103
4.3.2. Motion blur ........................................................................................................................................................................................................ 108
5. CORONA - Performance TAB ..................................................................... 111
5.1. GLOBAL ILLUMINATION .............................................................................................................................................................. 111
5.1.1. Global Illumination .......................................................................................................................................................................................... 113
5.1.2. Path Tracing (PT) .............................................................................................................................................................................................. 114
UHD Cache (UHD) .............................................................................................................................................................................................. 119 5.1.3.
5.1.4. 4K Cache (4K) ..................................................................................................................................................................................................... 137
5.2. PERFORMANCE SETTINGS ....................................................................................................................................................... 147
5.2.1. Sampling balance ........................................................................................................................................................................................... 147
5.2.2. Speed vs. Accuracy balance ..................................................................................................................................................................... 153
5.2.3. Displacement & CoronaDisplacementMod ....................................................................................................................................... 157
5.2.4. Interactive rendering ................................................................................................................................................................................... 175
5.2.5. Caustics solver ................................................................................................................................................................................................. 177
5.3. DEVELOPMENT / EXPERIMENTAL STUFF ............................................................................................................................ 186
5.3.1. Introduction....................................................................................................................................................................................................... 186
5.3.2. Basic configuration ...................................................................................................................................................................................... 189
5.3.3. Adaptivity and denoising ........................................................................................................................................................................... 196
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Interactive Rendering .................................................................................................................................................................................. 198 5.3.4.
Hair rendering .................................................................................................................................................................................................. 199 5.3.5.
Lights ................................................................................................................................................................................................................... 200 5.3.6.
5.3.7. Terminator handling ..................................................................................................................................................................................... 201
String options .................................................................................................................................................................................................. 204 5.3.8.
6. CORONA - System TAB ................................................................................ 207
6.1. CORONA SYSTEM SETTINGS ................................................................................................................................................... 207
6.1.1. System settings ............................................................................................................................................................................................... 208
6.1.2. Interactive rendering .................................................................................................................................................................................. 208
6.1.3. Autosave .............................................................................................................................................................................................................. 214
6.1.4. VFB Settings ....................................................................................................................................................................................................... 215
6.1.5. Render history and A/B comparison..................................................................................................................................................... 216
6.1.6. Tooltips and Material editor ...................................................................................................................................................................... 216
6.2. FRAME BUFFER ............................................................................................................................................................................ 219
6.2.1. Render stamp .................................................................................................................................................................................................... 219
6.2.2. Filters ................................................................................................................................................................................................................... 220
6.3. ABOUT CORONA RENDERER / LICENSING ........................................................................................................................ 229
6.4. DISTRIBUTED RENDERING ...................................................................................................................................................... 231
6.4.1. Slave (Port 19667) .......................................................................................................................................................................................... 234
6.4.2. Master (Port 19666) ...................................................................................................................................................................................... 234
6.4.3. Settings .............................................................................................................................................................................................................. 234
6.4.4. Image data ........................................................................................................................................................................................................ 234
6.4.5. 3dsMax version .............................................................................................................................................................................................. 236
6.4.6. Log ......................................................................................................................................................................................................................... 236
6.4.7. The DR .................................................................................................................................................................................................................... 237
7. CORONA - Render Elements TAB ............................................................ 241
7.1. INTRODUCTION ............................................................................................................................................................................ 241
7.2. CESSENTIAL.................................................................................................................................................................................. 242
7.3. CGeometry .................................................................................................................................................................................. 246
7.3.1. CGeometry_Normals ..................................................................................................................................................................................... 246
7.3.2. CGeometry_UvwCoords .............................................................................................................................................................................. 250
7.3.3. CGeometry_Velocity .................................................................................................................................................................................... 254
7.3.4. CGeometry_WorldPosition ....................................................................................................................................................................... 256
7.3.5. CGeometry_ZDepth ....................................................................................................................................................................................... 259
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7.4. CInfo ............................................................................................................................................................................................... 262
7.4.1. CInfo_NetworkRenderDebugging ......................................................................................................................................................... 262
7.4.2. CInfo_RenderStamp ..................................................................................................................................................................................... 263
7.4.3. CInfo_SamplingFocus ................................................................................................................................................................................. 263
7.5. CMasking ..................................................................................................................................................................................... 264
7.5.1. CMasking_ID ......................................................................................................................................................................................................264
7.5.2. CMasking_Mask ............................................................................................................................................................................................. 266
7.5.3. CMasking_WireColor ................................................................................................................................................................................... 267
7.6. CShading .................................................................................................................................................................................... 268
7.6.1. CShading_Albedo .......................................................................................................................................................................................... 268
7.6.2. CShading_Alpha ............................................................................................................................................................................................. 269
7.6.3. CShading_Beauty .......................................................................................................................................................................................... 269
7.6.4. CShading_BloomGlare ............................................................................................................................................................................... 269
7.6.5. CShading_Caustics ....................................................................................................................................................................................... 270
7.6.6. CShading_Components .............................................................................................................................................................................. 270
7.6.7. CShading_RawComponent ........................................................................................................................................................................ 272
7.6.8. CShading_Shadows ...................................................................................................................................................................................... 273
7.6.9. CShading_SourceColor .............................................................................................................................................................................. 273
7.6.10. CTexmap ............................................................................................................................................................................................................ 275
7.6.11. CShading_LightSelect ................................................................................................................................................................................ 276
8. CORONA - OBJECTS ........................................................................................ 279
8.1. INTRODUCTION ........................................................................................................................................................................... 279
8.2. CORONA LIGHT .......................................................................................................................................................................... 280
8.2.1. Theoretical basis of illumination .......................................................................................................................................................... 280
8.2.2. Parameters ........................................................................................................................................................................................................ 297
8.3. CORONA SHADOWS ................................................................................................................................................................. 308
8.4. CORONA SUN .............................................................................................................................................................................. 309
8.5. CORONACAMERAMOD ............................................................................................................................................................. 318
8.5.1. Introduction....................................................................................................................................................................................................... 318
8.5.2. Stereoscopic view, 360° view, and VR ................................................................................................................................................. 321
8.6. CORONA CAMERA ..................................................................................................................................................................... 330
8.6.1. Introduction ..................................................................................................................................................................................................... 330
8.6.2. Parameters ........................................................................................................................................................................................................ 331
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8.7. CORONA FRACTAL ...................................................................................................................................................................... 343
8.8. CORONA PROXY ......................................................................................................................................................................... 355
8.9. CORONA SCATTER .................................................................................................................................................................... 360
8.10. CORONA VOLUME GRID ......................................................................................................................................................... 379
8.10.1. Introduction ..................................................................................................................................................................................................... 379
8.10.2. Parameters ..................................................................................................................................................................................................... 382
9. CORONA - MATERIALS ................................................................................... 401
9.1. INTRODUCTION ........................................................................................................................................................................... 401
9.2. CoronaMtl ................................................................................................................................................................................... 402
9.2.1. Basic options .................................................................................................................................................................................................... 403
9.2.2. Diffuse ................................................................................................................................................................................................................. 403
9.2.3. Translucency .................................................................................................................................................................................................... 407
9.2.4. Reflection ........................................................................................................................................................................................................... 410
9.2.5. Refraction ........................................................................................................................................................................................................... 418
9.2.6. Opacity ................................................................................................................................................................................................................ 426
9.2.7. Displacement ................................................................................................................................................................................................... 429
9.2.8. Absorption ......................................................................................................................................................................................................... 430
9.2.9. Subsurface Scattering (SSS) ................................................................................................................................................................... 433
9.2.10. Mode: Volumetric scattering ................................................................................................................................................................ 434
9.2.11. Mode: SSS ......................................................................................................................................................................................................... 450
9.2.12. Advanced options ........................................................................................................................................................................................ 455
9.3. CoronaLightMtl ........................................................................................................................................................................ 469
9.4. CoronaLayeredMtl .................................................................................................................................................................. 477
9.5. CoronaPortalMtl ...................................................................................................................................................................... 481
9.6. CoronaRaySwitchMtl ........................................................................................................................................................... 484
9.7. CoronaShadowCatcherMtl ................................................................................................................................................ 488
9.7.1. Matte/Shadow .................................................................................................................................................................................................. 493
9.7.2. Reflection properties ................................................................................................................................................................................... 496
9.7.3. Project backplate options ......................................................................................................................................................................... 499
9.8. CoronaVolumeMtl .................................................................................................................................................................. 501
9.8.1. Parameters ........................................................................................................................................................................................................ 503
9.8.2. Tutorial - 1 ........................................................................................................................................................................................................... 511
9.8.3. Tutorial - 2 .......................................................................................................................................................................................................... 513
9.8.4. Tutorial - 3 .......................................................................................................................................................................................................... 519
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9.9. CoronaSkinMtl ........................................................................................................................................................................ 526
9.9.1. Introduction ..................................................................................................................................................................................................... 526
9.9.2. Parameters ....................................................................................................................................................................................................... 528
9.10. CoronaHairMtl ....................................................................................................................................................................... 535
9.10.1. Introduction ................................................................................................................................................................................................... 535
9.10.2. Parameters ...................................................................................................................................................................................................... 537
9.11. CoronaSelectMtl .................................................................................................................................................................. 549
10. CORONA - MAPS ............................................................................................ 551
10.1. INTRODUCTION ......................................................................................................................................................................... 551
10.2. CoronaBitmap ....................................................................................................................................................................... 552
10.2.1. Environment mode ...................................................................................................................................................................................... 552
10.2.2. Dome mode ..................................................................................................................................................................................................... 555
10.3. CoronaColor ........................................................................................................................................................................... 560
10.3.1. Color input ....................................................................................................................................................................................................... 560
10.3.2. Advanced ......................................................................................................................................................................................................... 565
10.3.3. Result color preview ................................................................................................................................................................................. 566
10.4. CoronaSky ................................................................................................................................................................................ 567
10.4.1. Corona Sky Texmap .................................................................................................................................................................................... 568
10.4.2. Rawafake model parameters ................................................................................................................................................................ 570
10.5. CoronaWire ............................................................................................................................................................................. 572
10.6. CoronaRoundEdges ............................................................................................................................................................ 578
10.6.1. Additional bump mapping ...................................................................................................................................................................... 582
10.6.2. Effect includes/excludes ....................................................................................................................................................................... 583
10.7. CoronaNormal ....................................................................................................................................................................... 586
10.7.1. Introduction .................................................................................................................................................................................................... 586
10.7.2. Parameters ..................................................................................................................................................................................................... 589
10.8. CoronaFrontBack ................................................................................................................................................................ 593
10.9. CoronaRaySwitch ................................................................................................................................................................ 595
10.10. CoronaColorCorrect ........................................................................................................................................................ 596
10.11. CoronaAO ................................................................................................................................................................................ 602
10.11.1. Introduction .................................................................................................................................................................................................. 602
10.11.2. Parameters ................................................................................................................................................................................................... 604
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10.12. CoronaMultiMap .................................................................................................................................................................. 611
10.12.1. Introduction ................................................................................................................................................................................................... 611
10.12.2. Parameters .................................................................................................................................................................................................... 612
10.13. CoronaMix .............................................................................................................................................................................. 619
10.13.1. Introduction ................................................................................................................................................................................................... 619
10.13.2. Parameters .................................................................................................................................................................................................... 619
10.14. CoronaDistance .................................................................................................................................................................. 630
10.14.1. Introduction .................................................................................................................................................................................................. 630
10.14.2. Parameters ................................................................................................................................................................................................... 635
10.14.3. Tutorial - Height .......................................................................................................................................................................................... 635
10.14.4. Tutorial - Gradient ...................................................................................................................................................................................... 637
10.14.5. Tutorial - Ocean .......................................................................................................................................................................................... 638
10.14.6. Tutorial - Scatter ........................................................................................................................................................................................ 639
10.14.7. Tutorial - Booleans .................................................................................................................................................................................... 643
10.15. CoronaTriplanar ................................................................................................................................................................. 646
10.15.1. Introduction .................................................................................................................................................................................................. 646
10.15.2. Parameters ................................................................................................................................................................................................... 648
10.16. CoronaUvwRandomizer .................................................................................................................................................. 652
10.16.1. Introduction .................................................................................................................................................................................................. 652
10.16.2. Parameters ................................................................................................................................................................................................... 653
10.17. CoronaBumpConverter ................................................................................................................................................... 662
10.17.1. Introduction ................................................................................................................................................................................................... 662
10.17.2. Parameters .................................................................................................................................................................................................... 664
10.18. CoronaTonemapControl ............................................................................................................................................... 666
10.19. CoronaSelect .......................................................................................................................................................................668
11. CORONA - SCRIPTS...................................................................................... 669
11.1. Script - Corona Converter ................................................................................................................................................. 670
11.2. Script - Open matlib v1.0 .................................................................................................................................................... 680
11.3. Script - Corona Official Toolbar ..................................................................................................................................... 683
11.4. Script - Corona Proxy Lister v1.0 .................................................................................................................................... 685
11.5. Other scripts ...........................................................................................................................................................................686
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INTRODUCTION - 1
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1. INTRODUCTION
1.1. GENERAL
1.1.1. Author information
Francesco Legrenzi was born in 1977 in a small Bergamo valley. After graduating as a construction engineer at the faculty of Milan, he worked for three years as a structural engineer. Realizing his true passion, he gave up his long-time job, devoting himself to the world of 3D graphics. In 2001 he was asked to participate in the management of a famous Italian 3D graphics forum, where he remained an active participant until 2010. In the meantime, in 2001 he became aware of a small plug-in, V-Ray, developed by Chaos Group, a Bulgarian software house. In 2005, he began writing what became one of the most referenced books for learning V-Ray: VRay - THE COMPLETE GUIDE. The success was unexpected: three reprints and an English version were made. Since then, he has immersed himself in the world of 3D, especially for the 3ds Max rendering engines. After years spent directing the Modeling & Lighting department in an architecture firm in Milan, the author began working as a freelancer. In 2013, he discovered (www.corona-renderer.com), a sofware Corona Rendererin Alpha 4 version. It was relatively unknown, but he decided to use it on a professional level. From that encounter a close collaboration was born with , which lead to the creation of this book. Chaos Czech a.s.
1.1.2. Acknowledgments
In 2008 I wrote VRay - THE COMPLETE GUIDE. It was my first book and many people offered their help. I would like to thank the following people for giving me courage and inspiration to complete my second volume. The first thank you must go to , without whom no one would have had the pleasure of this program, Ondra Karlik
and I would not have had the honor of writing the world’s first guide for Corona Renderer. To my beloved parents, Tomaso and Megi. Without their financial and moral support, I would never have
completed this book. Their examples of life, their union, their consistency, intelligence, understanding, and tenacity will always be my point of reference.
To www.textures.com for its free textures and the ability to distribute them. To www.3dsky.org for the free models. To www.hdri-skies.com for the free HDRI maps and permission to distribute them. To Toni Bratincevic for his precious tutorial on Anti-Aliasing. To www.pixabay.com for their image archive. To www.omlc.org for the radiometric exercises. To www.coronamaterials.com for the free shaderball model. To DeadClown (Martin Geupel - www.racoon-artworks.de) for the script he wrote for the book. Open matlib v1.0 To www.hdrmaps.com and www.hdrshop.com for the free HDRI maps. To toolset.mrwebmaster.it for information regarding the conversion from Hex to RGB.
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2. CORONA RENDERER
2.1. CORONA RENDERER’S HISTORY By . Ondra Karlík I have always been fascinated by CG. I started using 3ds Max at the age of 15, trying to create photorealistic images with all my effort and passion ( Fig. 2.1). Initially, CG was a hobby, but I always felt it may become my future. I stopped being a designer to create a program for the college of computer science, with the purpose of learning to code. The course was demanding, so I temporarily abandoned the world of 3D.
Fig. 2.1 Renders created by Ondra Karlik.
2.1.1. Ondra’s College Years
In 2009, with my graduation coming, I had to choose the topic for my thesis. I had an agreement with a faculty teacher to create a web timetable for the university, but I decided to do something different: a friend advised me to write a rendering program. At first, I thought it would be too complicated, but then I convinced myself and started to plan what would later become Corona Renderer. The first version was basic, did not support Global Illumination and had no connection with other 3D applications. In fact, the target of the thesis was not creating a commercial rendering engine, but comparing rendering algorithms ( Fig. 2.2).
Fig. 2.2 Images made with an embryonic phase of Corona Renderer. From left to right: the first render saved by Corona Renderer, the first render with multiple objects, and the
first shader with “electronic microscope” effect.
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3. CORONA - Scene TAB
3.1. GENERAL SETTINGS In this section we discuss the control panel of Corona called , but first we should clarify how Corona “thinks”. Scene The strength of this extraordinary software lies in its simplicity. The engine under its hood is called Progressive Path Tracing (PT). In 2013, V-Ray or Mental Ray users will remember wasting time looking for the best settings to achieve an optimal render without artifacts. Often, due to lack of time or poor knowledge of the software, it was common to use parameters found online or in tutorials (often incorrect). Other times we proceeded “by groping”, in the hope of having guessed the correct parameters, or we used very high values sure of an excellent result at the expense of rendering times. Thus, in the V-Ray Virtual Frame Buffer, a preview began to appear due to the biased system of the software; then, small rectangles called buckets appeared ( Fig. 3.1). Piece by piece, the final image took shape and the software gave us a rough time estimate, but the actual total rendering time could vary, depending on the complexity of the image.
Fig. 3.1 Example of how various rendering engines calculated images. Unless using the new progressive rendering systems, the classic rendering engines (Scanline, Mental Ray, V-Ray, Final Render, etc.) did not allow us to view the overall image, but they proceeded with horizontal lines or square buckets. Moreover, it was often necessary to modify many parameters (of rendering, materials, and lights) to quickly obtain a quality render.
Since the first versions (back in 2012), Corona adopted a completely different approach, which was then copied by Alphamany other rendering engines. The user no longer had to set up dozens of parameters or waste time with hundreds of rendering tests. The main parameters were optimized to achieve the highest quality in the shortest time. From the first few seconds we had a precise idea of the final result, and it was the user who decided how long Corona had to calculate the render ( Fig. 3.2). Naturally, the longer the time, the greater the quality (cleanliness) of the image. With the accurate estimate provided by Corona, it was very easy to determine how long an image had to “cook” to be perfect. We no longer had to feel frustrated looking for the best values. We no longer had artifacts, splotches, or “flying” objects without shadows, as Corona automatically solved these problems for us. Reading this book, we will realize how amazing it is to work with Corona. Under the influence of Corona, many other software houses introduced a similar calculation system in their rendering engines. Corona was born as a progressive rendering engine with simplicity as its winning card, and it is one of the most efficient CPU rendering systems on the market.
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4. CORONA - Camera TAB This TAB contains three rollouts: (Sect. 4.1), (Sect. 4.2), and (Sect. 4.3). Also, Postprocessing Bloom and Glare Camerathe rollout allows us to manage ( ) (Sect. 4.3.1) and (Sect. 4.3.2). Camera Depth of field DOF Motion blur
Fig. 4.1 The three rollouts of Camera TAB: Postprocessing, Bloom and Glare, and Camera.
4.1. POSTPROCESSING This rollout is divided into four sections: , , , and . By Tone mapping Basic photographic settings LUT Sharpening/Blurringmodifying the values in the Corona , those of the rollout are automatically updated, giving us the same VFB Postprocessingvalues in two different positions of the interface ( Fig. 4.2). The parameters are more Basic photographic settingscomplex and are not reflected in the . VFB
Fig. 4.2 The Postprocessing rollout with four groups: Tone mapping, Basic photographic settings, LUT, and Sharpening/Blurring.
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5. CORONA - Performance TAB Although Corona is a young rendering engine, a large number of professionals already adopted it as the main tool for their projects. The perfect balance of its parameters allows us to obtain excellent results, even for the less experienced users. The default values are optimized to achieve the right balance between quality and performance. However, in some cases the user might need to change the default settings. In this section we will discuss Corona advanced parameters ( Fig. 5.1):
( ); Global Illumination GI ( ) and ; Anti-Aliasing AA noise ; Displacement ( ); Interactive Rendering IR ; Caustics / ( / ); 4K UHD Cache 4K UHD Corona (developmental and experimental parameters). Core
Fig. 5.1 The eight Performance TAB rollouts.
5.1. GLOBAL ILLUMINATION Global Illumination (GI) is a useful tool to generate photorealistic images. In the following pages we will learn how to improve lighting quality with the use of GI. The scene in Fig. 5.2 consists of a room illuminated by the system. The first two renders are Corona Sun+Corona Skyvery different from each other due to the use of Global Illumination. When the GI processing is disabled, Corona only calculates direct light (i.e. only objects directly exposed to light are illuminated). When GI is enabled, it calculates both direct and indirect light, and the room will be illuminated in a photorealistic way.
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6. CORONA - System TAB In the previous three chapters, the more complex parameters of Corona were analyzed, explaining how the software “thinks”. In the ( Fig. 6.1), service parameters are found. Except for the group tools, all other System TAB Image filterparameters do not affect the render quality, but take action in the Corona management.
Fig. 6.1 The three System TAB rollouts: Frame Buffer, About Corona Renderer/Licensing, and Distributed Rendering.
6.1. CORONA SYSTEM SETTINGS The button in the upper left opens a window containing useful tools to control the rendering process. They System Settingsare slightly hidden, as they rarely need to be changed during normal use of Corona ( Fig. 6.2).
Fig. 6.2 The Corona System Settings window is divided into eight sections.
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7. CORONA - Render Elements TAB
7.1. INTRODUCTION A render consists of colors, shadows, reflections, refractions, and volumetric effects. With the Render Elements module (RE) we will be able to divide a render into “layers” representing parts or proprieties of the final image ( Fig. 7.1). Then, with programs dedicated to post-production, these layers can be used for various purposes, such as reconstructing the final render, creating masks, and generating technical renders.
Fig. 7.1 Example of render reconstructed by combining several layers. Some REs extract additional information from the 3D scene, such as the Depth map (Sect. 7.3.5), Ambient Occlusion (Sect. 7.6.10), or the CGeometry_Velocity RE used for the post-production calculation of Motion blur (Sect. 7.3.3).
The purpose of separating a render into individual elements is to modify its properties once the render is completed. For example, if the reflections are not very visible, we will not have to recalculate the entire render, but it will be enough to modify the reflections layer, thus saving a lot of time. The Render Elements window is located on the Render Elements TAB. When Corona is set as the rendering engine, the 3ds Max REs disappear and the Corona REs will be displayed. 32 REs are available ( Fig. 7.2), each with unique features capable of isolating a specific property of the image.
Fig. 7.2 After clicking the Add... button (1), a new window will appear to choose the REs we need (2). In this example, the seven REs of the CESSENTIAL category were enabled. Once the main render save folder is determined (F10 → Common TAB Parameters → Render Output), Corona will correctly rename each RE save path.
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8. CORONA - OBJECTS
8.1. INTRODUCTION With Corona installed, new 3ds Max tools are available to create and control multiple aspects of a 3D scene. In this chapter we will describe the following objects:
Corona Light: Corona proprietary light. is a better alternative than 3ds Max Standard lights. Also, Corona Light includes some tools not available in 3ds Max lights (Sect. 8.2). Corona Light
Corona Shadow: designed exclusively for use with the 3ds Max Standard lights (Sect. 8.3).
Corona Sun: together with the map, this light source simulates the sun and controls the look of the Corona Skysky (Sect. 8.4).
CoronaCameraMod: modifier to add physical parameters (ISO, F-stop, etc.) to the Standard camera (Sect. 8.5).
Corona Camera: camera specifically designed and optimized for Corona (Sect. 8.6).
Corona Fractal: parametric object capable of generating 3D fractals (Sect. 8.7).
Corona Proxy: replaces a heavy geometry with a lighter version. For example, we will be able to process a forest made up of millions of polygons without overloading the RAM (Sect. 8.8).
Corona Scatter: tool to distribute millions of objects on a surface (Sect. 8.9).
Corona Volume Grid: tool to import .vdb files (OpenVDB) (Sect. 8.10).
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9. CORONA - MATERIALS
9.1. INTRODUCTION A material is able to assign physical properties to objects, such as color, transparency, refraction, opacity, or translucency. In addition, there are also special materials to be used for specific situations. For example, can generate CoronaVolumeMtlfog or clouds (Sect. 9.8), and can turn a mesh into a light source (Sect. 9.3). However, will be CoronaLightMtl CoronaMtlthe most used shader, as it can reproduce a wide variety of materials: plastics, glass, liquids, etc. This chapter will analyze all nine Corona materials available at the time of writing this book ( Fig. 9.1).
Fig. 9.1 The nine Corona proprietary materials. In the preview we see CoronaHairMtl, the shader dedicated to hair simulation.
Corona also allows us to use 3ds Max materials. Some shaders are 100% compatible (e.g. Blend, Double Sided, Multi/Sub-Object, Shell Material, Standard, Top/Bottom, XRef Material), while others are not supported. When a material is not compatible, the following image appears in the Material Editor ( Fig. 9.2).
Fig. 9.2 When Corona does not support the material, the object will be rendered in bright red with the text “Unsupported mtl”. In this example, 3ds Max Arch & Design material was selected. Note: the Corona Error Message(s) window warns us of problems with the Arch & Design material.
Except for the Blend and Multi/Sub-Object shaders, different materials from those offered by Corona will rarely be needed.
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10. CORONA - MAPS
10.1. INTRODUCTION With the Corona materials we can assign properties such as color, reflection, refraction, and self-illumination to objects, while with maps more details can be added to these properties. In the following test, a will be used to create the Corona logo by loading a in the CoronaMtl CoronaBitmap Diffusechannel and a black and white image in the channel ( Fig. 10.1). Opacity( ) Ch10_01_Maps.max
Fig. 10.1 CoronaBitmap loaded in the Diffuse and Opacity channels. Now the logo has four rounded corners thanks to the opacity map.
Corona provides twenty new maps ( Fig. 10.2), which will allow us to assign colors, mix maps, simulate the sky, and much more.
Fig. 10.2 The twenty maps of Corona. The CoronaData map will not be analyzed, as it is only useful for debugging and in other rare situations. CoronaUserProperty will also be omitted as well, as it is useful only for PRO users who need to create scripts.
For a more in-depth explanation of the 3ds Max maps and how to use them in the Material Editor, it’s advised to look at the countless tutorials on the web.
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11. CORONA - SCRIPTS A scripting language is a method to easily access the internal functions of a software. MAXScript is a programming language to manage and execute particular tasks in 3ds Max. Unlike plug-ins (files usually written in C ++), scripts are a list of instructions read and run step-by-step by 3ds Max. For example, a script can be represented by the following lines of code:
Instruction 0: if at least one object is selected, go ahead.
Instruction 1: choose the material of the currently selected object.
Instruction 2: ask the user if they want to view this material in wireframe.
Instruction 3: then enable the wireframe option of the selected material if the user answers yes. Imagine this list written in a .txt file. Thanks to the 3ds Max scripting engine, it will be possible to select an object in the scene and “ask” the software: “Open the list of instructions and run the code”. This example is very simple, but we can understand how easy it is to handle 3ds Max. In 3ds Max there is a program called MAXScript Editor (similar to Windows Notepad) for creating and reading scripts ( Fig. 11.1).
Fig. 11.1 To create a script, click MAXScript → MAXScript Editor... . A new window will open for creating our first script. The image shows the coronaConverter_v1.45.ms script. Once executed, it will allow us to convert a 3ds Max file created with V-Ray into a Corona native file. This script is made of 4,620 lines.
The MAXScript Listener tool is another way to execute a script (i.e. an interface to run commands “on-the-fly” without saving the script in a file). For example, let’s try to open the Listener window (MAXScript → MAXScript Listener...) and type the following command: messagebox (“HELLO” + sysInfo.username + “!”) as string Go to the end of the line and press ENTER ( Fig. 11.2).
Fig. 11.2 A very simple script.
