Hey Matt, Your result might be different because of the tangent space calculation. I suppose that the normal map calculation might be done in object space, then Ultimapper converts it into tangent space. Ultimapper could be quite good, but lacks a very important feature, the cage. So finally we dropped in favor of xNormal.
You might check few things (I'm not a programmer, so I may be wrong). Check the transforms. In my experience transforms has effect how vertex normals are calculated. Certain distance from the origin might result imprecision (is this the right word?), and the farther the object is from the origin, the bigger this imprecision is. There are discrepancies, for sure, because these tools have different approach to derive tangent space. For example, Softimage uses the vertex color to store the tangents, and binormal is calculated from this. But, if your smoothing on the geo and on the tangent space property differs, you won't get any usable normal map. For example the smoothing on tangents made Ultimapper quite useless for us, so I wrote an exporter for xNormal, and since then we have no issue at all. As our technical chief explained, a normal is correct only if the normal baking and displayer use the same tangent calculation. He wrote a tangent space calculator for xNormal, that uses the same algorithm CryEngine uses. So, unless your game engine approached tangent space differently than Softimage, you won't get good result. I think the whole game pipeline should be redesigned in Softimage... From: [email protected] [mailto:[email protected]] On Behalf Of Matt Lind Sent: Friday, January 03, 2014 5:17 AM To: [email protected] Subject: ultimapper issues - tangent space normal maps I am writing a modified ultimapper to convert tangent space normal maps from one mesh to another. The tool is needed because our tangent space normal maps are not encoded in the standard way and softimage's tools cannot be modified to support our proprietary tangent space. For prototyping I'm using the softimage tangent space and tangents property to do the transfer so I can check my math against ultimapper. Once I get a 1:1 match, I'll modify the logistics to support our proprietary stuff. So far when the hi and low res meshes are untransformed I get a 1:1 match with ultimapper, but when I transform one or both meshes a wide discrepancy appears between my result and the softimage ultimapper result. The softimage result tends to be significantly brighter on the red and green channels, mostly on the green. In some cases, the colors are not even close to the same. The odd part is when I trace through the process step by step to debug, my numbers look correct both visually and mathematically. I'm in a weird situation in that I do not know who's result is more correct, mine or Softimage. Some of our artists have mentioned there have been some discrepancies compared to other commercial normal mapping tools (beyond flipping the Y axis). Has anybody had issues getting correct results from ultimapper when transferring tangent space normal maps between meshes? Matt
