Post on 02-Apr-2018
Me Again!
Peter Chapman | Bradford University
Peter Chapman
P.Chapman1@bradford.ac.ukpchapman86@gmail.com – if it’s important / time-sensitive
Issues? Working on something specific? Need some direction?
Don’t hesitate to get in touch
http://peter-chapman.co.uk/teaching
2016 | Intro to 3D | Week 06 | Rendering
Rendering theory & practice
Peter Chapman | Bradford University
• This can be the most time consuming part of the process depending on the complexity of your scene
• Many people underestimate the time needed
• Can easily be a massive time-drain!
2016 | Intro to 3D | Week 06 | Rendering
Introduction
Peter Chapman | Bradford University
• Scene complete = time to start rendering!• How do you want to render it?• Should think about rendering all the way through your
production –don’t leave it till the end!• Create models and textures with the final image in
mind• Gear lighting towards showing off the scene
• Which renderer?• Maya software, Maya hardware, Mental Ray, Maya
vector, Vray, Octane
2016 | Intro to 3D | Week 06 | Rendering
Different Renderers
Peter Chapman | Bradford University
• Each engine renders differently and can give entirely different results
• Choice depends on:• the final look you want• number of machines you have• Number of licenses you have• Time / Budget
• It’s best to choice the render engine before you begin creating your scene and essential before lighting and shading.
2016 | Intro to 3D | Week 06 | Rendering
Some Basics
Peter Chapman | Bradford University
• Choose an appropriate resolution and aspect ratio – where will the final output be displayed?
• ALWAYS Render to frame files rather than movie files• Open iff from maya, or png / tiff but never jpeg!
• Use file formats that use no compression or loss-less compression
• Use anti-aliasing (within reason)• Use Ray tracing wisely (expensive)• Don’t just ramp everything to max! Be smart!
2016 | Intro to 3D | Week 06 | Rendering
Which is best and why?
Peter Chapman | Bradford University
• discuss
2016 | Intro to 3D | Week 06 | Rendering
Maya Software
Peter Chapman | Bradford University
• Default software rending solution• Can capture just about anything you want in your scene
• Reflections, Motion Blur, Transparencies• Good one to start with• Render quality depends on anti-aliasing and ray-tracing• Often under-estimated• Can be fantastic when combined with an occlusion pass
2016 | Intro to 3D | Week 06 | Rendering
Maya Hardware
Peter Chapman | Bradford University
• Uses your graphics card’s processor to render (but not the same as GPU renderers such as Octane)
• Similar to what you will see when you play a 3D video game
• Data output by the game is fed directly into the graphics pipeline and rendered on the fly as you play.
• Results in faster render times, but lacks some of the features and quality you get from software render
• Don’t use it
2016 | Intro to 3D | Week 06 | Rendering
Mental Ray
Peter Chapman | Bradford University
• Now included and heavily integrated into Maya• True Physical render engine allows amazing realism• Emulate the behaviour of light more realistically• Can be an advanced renderer with shaders and procedures
of it’s own• Can be used to generate occlusion passes
2016 | Intro to 3D | Week 06 | Rendering
GPU Renderers (Octane / Vray)
Peter Chapman | Bradford University
• Use advanced GPU’s (usually Nvidea CUDA cores) to render very quickly and realistically using the architecture of a GPU – hundreds (or thousands) of cores doing simple things rather than a few powerful cores such as a CPU
• Requires using it’s own shaders / cameras etc
2016 | Intro to 3D | Week 06 | Rendering
Global Illumination
Peter Chapman | Bradford University
• This simulates the interaction of light with the entireenvironment rather than individual surfaces
• Light is tracked from emitters to sensors• Shadows are automatically generated, as are interactions
between surfaces• There are two common approaches: ray tracing and
radiosity• Before we look at these in detail, we should look at some
general features of global illumination
2016 | Intro to 3D | Week 06 | Rendering
Global Illumination
Peter Chapman | Bradford University
• Ignoring the fact that the calculations (as we shall see later) are complex, the solution to global illumination is simple:
• Start at a light source• Trace every light path through the environment until it
either:• Hits the eye point• Has its energy reduced below a threshold• Travels out of the environment
2016 | Intro to 3D | Week 06 | Rendering
Surface to Surface
Peter Chapman | Bradford University
• We can also model the way one surface interacts with another
• This is easier to consider non-mathematically• Four different interactions:
• diffuse to diffuse• specular to diffuse• diffuse to specular• specular to specular
• Colour bleed, colour in shadows, etc
2016 | Intro to 3D | Week 06 | Rendering
A Classic Ray-Traced Scene
Peter Chapman | Bradford University
2016 | Intro to 3D | Week 06 | Rendering
Simple Rendering Best Practice
Peter Chapman | Bradford University
• Model & Texture appropriately• Level of detail needed not over done• Close objects high detail…objects further way less
• Use line render, play blasts, test renders• Avoid mistakes re-rendering costly
• Only use features necessary• Paint effects, final gather etc all take time
• Split your scene up• Multi-pass / Batch rendering / Network Rendering /
Distributed Rendering where appropriate
2016 | Intro to 3D | Week 06 | Rendering