03/06/2008

Particle Rendering in ParaView

Attention

These slides are incomplete

and are provided for the IEEE Vis 08 DVD.

• The complete and full set of slides will be available from the CSCS web site under the following link

https://twiki.cscs.ch/twiki/bin/view/ParaViewMeshless/ParticleRendering

• And in the event of broken/changed link, from the ParaView3 Wikihttp://www.paraview.org/Wiki/ParaView

Representation/Display

• Standard Display panel• Surface/ Wireframe/ Points• Colour editor• Point Size• (Cube Axes)• (Interpolate)• Opacity

Color Editor (colour really)

Change Presets Define your own Load Save Scale Log/Lin Fit to data (See Track changes) Change Color Space

(interpolation between RGB values)

Manually edit scale

Point Sprite Representation

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Opacity control Track changes (max/min) 3 render modes Simple point

As before, but with opacity Sprite

A sphere, clearer contrast Shader

Radius controls

Opacity

Auto Min/Max changes with scalar

Enable disable auto change

Set min max manually Values <min mapped to 0, >max, to 1 Values from 0-1 mapped to

range according to opacity control setting

Can also change overall value with slider (<1)

Opacity

03/06/2008

Gaussian control Select peaks Drag left/right Drag up/down Scale/shrink

Great for volumetric datasets

Background color map for opacity

03/06/2008

When colour and opacity have same variable and same range

Not 100% accurate, but useful

Volume render effect

Volume animation (shown last year at spheric)

PointSize

• Change size according to taste• All particles the same• No perspective (well actually yes, but not accurate)• No relative scale between particles

• Try zooming in/out

• Point smoothing changes particles to rounded squares/ almost circles

• NB. Bug. If Point Sprite selected, then simple point selected, size clamped.

Depth Sort

• For transparency – particles must either be sorted back to front

• Cout = Csrc * Asrc + (1 - Asrc) * Cdst• Skip anything behind closest pixel• Colour correct

• Alpha can get messy when compositing images in parallel – distributed overlap/sort

TURN OFF DEPTH SORT FOR FASTER DISPLAY

Wrong Right

Depth Peeling

• Instead of sorting every object and drawing back to front• Draw everything once and save the image• Then draw it again, but only items in front of last one• Then do it again, and again in ‘peels’• Objects are not sorted, but each pass renders stuff in front, gradually

the final image is built up.• Not bad for brains/bones• Awful for lots of particles• Uses advanced shaders which mess up our renderer• Work in progress is getting depth peeling working with our renderer

Sprite mode

• Spheres are drawn with shaded edges• Improves contrast

Shader mode

• Better for smaller datasets• Where a parameter is to be highlighted

Ellipsoids : Quadrics : To be continued