l e v e l - o f - d e t a i l


The animations on this page demonstrate the support offered by RenderMan for level-of-detail (LOD). Three models of a saw palmetto were made in Maya. Using LOD the renderer chooses the appropriate model to use based on the area of screen space occupied by the model.



Low Res Leaf Med Res Leaf

Reference images.


Low Res Leaf Med Res Leaf High Res Leaf

I started off building three versions of one palm leaf. This would later be used to build an entire plant and then that plant used in a Level of Detail (LOD) project.
The low res version uses only Maya curves. The medium res was made of simple polygon planes and the high res was part nurbs and polygons.




Using planes, I created a proxy leaf, an object to represent the leaf, and then create the entire plant with these planes.




In a similar fashion, I then take the entire plant and create a new box to axt as the proxy for the entire bush.
This is then the object I use in Maya as my 'plant' and I can place them anywhere I want. The second image is the render
of the plant from the proxy box model.




Using the Level of Detail in Renderman, I created a line of bushes. The different colors mark where the low medium and
high res models change over. Using this method, you can greatly increase rendering time as you dont need to render high
detailed models far away in your scene. Click the image for a larger view. 

TransformBegin
	Detail [-1.1 1.1  0 5.3  -2.5 .83]
		
	DetailRange [ 1 1 6000 8000 ]
			#Color 1 0 0
			ReadArchive "G:/projects/PalmFrond/palmetto/branch/lowres2.rib" 
			
	DetailRange [ 6000 8000 20000 70000 ]
			#Color 0 1 0
			ReadArchive "G:/projects/PalmFrond/palmetto/branch/medres2.rib" 
					
	DetailRange [ 20000 70000 2000000 2000000 ]
			#Color 0 0 1
			ReadArchive "G:/projects/PalmFrond/palmetto/branch/highres2.rib" 
TransformEnd




Adding a simple ramp and blinn color and a light source with shading.




One of two animations showing LOD in action. This one is as seamless as I can get the transition so its
hard to tell just where the transitions are. (Shadows werent working from the render farm, I need to re-investigate)




The 'bad' version where I changed some values of the LOD pixel coverage to demonstrate how to deliberately make
the transition between the three models noticable. Instead of a gradual change, I kept the pixel numbers the same
as my way of making the change obvious. 

TransformBegin
	Detail [-1.1 1.1  0 5.3  -2.5 .83]
		
	DetailRange [ 1 1 6000 6000 ]
			#Color 1 0 0
			ReadArchive "lowres2.rib" 
			
	DetailRange [ 6000 6000 35000 35000 ]
			#Color 0 1 0
			ReadArchive "medres2.rib" 
					
	DetailRange [ 35000 35000 2000000 2000000 ]
			#Color 0 0 1
			ReadArchive "highres2.rib" 
TransformEnd