03. level of detail
The animations on this page demonstrate the support offered by RenderMan for
level-of-detail (LOD). Three models of a gumball seed were made in Maya/Houdini.
Using LOD the renderer chooses the appropriate model to use based on the area
of screen space occupied by the model.
a) The three models used in this assignment:
b) Level of detail transition ranges:
AttributeBegin
Detail [-.5 .5 -.5 .5 -.5 .5]
Color 1 0 0
DetailRange [ 1 1 700 3000 ]
ReadArchive "M:/Maya/projects/default/archives/suchan20_low.rib"
Color 0 1 0
DetailRange [ 700 3000 100000 150000 ]
ReadArchive "M:/Maya/projects/default/archives/suchan20_med.rib"
Color 0 0 1
DetailRange [ 100000 150000 400000 400000 ]
ReadArchive "M:/Maya/projects/default/archives/suchan20_high.rib"
Displacement "emboss" "Km" .02 "texname" ["gumball_displace.tx"]
Attribute "bound" "displacement" [0.1]
ReadArchive "M:/Maya/projects/default/archives/suchan20_high_core.rib"
AttributeEnd
c) Work in progress breakdown of ambient occlusion:
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01. This is rendered with the plastic shader. The displacement map is visible on the core of the model.
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02. Adding the ambient occlusion shader on the model created this result. This happens because the "ReverseOrientation" tag wasn't added before the transforms. Without this tag, the occlusion is happening inside the model, instead of outside.
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03. This render shows the fixed orientation of the occlusion, but there seems to be some black veins appearing on the surface where the displacements would be. This happens because ambient occlusion emits rays from the source of the object, the core. This means that the displacement that raises the geometry creates an invisible wall which shades the rays from those areas, creating the dark patches you see.
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04. Disabling the displacement map yielded better results as far as distribution of light on the gumball. There was still something missing, and thus the idea was presented...
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05. Reverse the displacement properties to allow the occulsion to still emit from the original surface, and not be shaded by the outward displacement. This is the results...
<- Click the image for a larger render.
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d) 360 rotation of ambient occlusion applied to the high resolution gumball:
*click to pause, double-click to resume*
The displacement map used to raise the ribs within the gumball:
!! The use of the high resolution model wasn't necessary so it was only substituted at the closest range from the camera !!
In the industry, it is common practice to use the lower resolution models as much as possible before transitioning to the higher resolution, this may not have a big impact on render time for our assignments, but applying this theory to a movie like Lord of the Rings, it significantly reduces render times.
e) Swap out distances between the 3 models.
f) A shower of gumballs.
g) Animation of Gumballs flying towards the camera
h) Animation of a single gumball cycling through the different levels of detail
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