Maya 2008 Displacements
It appears that a lot of people are having problems with Maya 2008 and rendering displacement maps. Two major changes have been made in Maya 2008 that impacts the ability to effectively render 32 bit displacement maps.
I did some reasearch and set up a mel script that will set up the scene file correctly. Thanks must go to those who found the problems with Maya 2008 early on. ZBC member marcotronic uncovered the CCMesh change.
The changes that Autodesk made are to the Alpha Detection and the mental Ray export mesh at render time. Maya 8.5 and earlier use Subdivision Surfaces at render time when a subdivision approximation node is assigned. Maya 2008 defaults to the CCMesh or Catmull Clark mesh. This is intended to be faster and support tris, ngons, and quads. The problem is it creates seams in the render.
I hope this helps. My thanks to everyone who has shared their experience and fixes on the forum especially marcotronic; who uncovered the new CCMesh primitive on the Autodesk site.
Scott
//COPY THE SCRIPT FROM HERE
// mental ray Subdivision Approximation script
// by scott spencer
//converts all subdivision approximation nodes in the scene from CCMesh to subdivision surface as well as sets the option
// to use maya style alpha detection
optionVar -iv “miUseMayaAlphaDetection” 1 -sv 1 1; //sets maya style alpha detection - mthe same as
// checking the Alpha is Luminance box in the file node but this works for all displacements in the scene
string $selected[] = ls -type mentalraySubdivApprox
; // selects each subdivision approximation node in the scene and adds to an arry
int $size = size ($selected)
; // creates the counter variable
for ($a=0;$a<$size;$a++) //increments thru the array
{//beginning of loop
string $name = $selected[$a]; // this variable accesses each element of select using $a as an index
addAttr -ln “miExportCCMesh” -at bool $selected[$a];
}
//END OF SCRIPT