Ive made this LoRes model in XSI, and after extracting tangent space normals I have ugly and inaccurate results. worlds space normals look allright, but I know I need tangent Nmap to make it work inside UE3.
I figured out that its because of my LoRes model having incorrect angent coordinates, but I dont know what caused it and how to fix that. Im also quite sure that my UVs are done well.
I will appreciate any help, or any links to tutorials that show how to make it right.
Tangent space smoothing angle could be the issue. Another possible cause is freezing the tangent operator and making topology/UV changes afterward.
Just discard your tangent info and create a new tangent op. See if that is the issue.
Tangents are like normals, and must be smoothed across surfaces or else you get hard edges everywhere, just like the discontinuity angle. For tangent smoothing, open up your tangents under objectname.cls.(*).Tangents
You’ll see smoothing under TangentOp2. Try setting it to 90°.
Thank you for you response. When I set smoothing to 90 I have almost no improvement, but when I cranked it up to 175+ I got this:
It looks way much better in the viewport, and freezing TangentOp prevented it from reversing back to previous state (which happened to me after first try). Now the problem is that after exporting it (Collada 1.4.1 - I want to use my models in Unreal Engine 3) I loose the smoothing, same if I try to export as .obj or .fbx. Its ok as long as I stay in Softimage, but when I export my mesh problem persists. I couldn’t find anything about that in help files, maybe I’m missing something…?
Tangents are not usually exported, so fixing it in SI wont help you for your target platform unless it takes into account user tangents. I don’t know of any engines that do, and i doubt collada supports tangent export without user modifications, and even then your engine would have to support import.
All that is usually exported from the modeling tool is point positions, point normals, UVs and vertex colors (and skin weights when necessary).
Tangents are usually rebuilt by the game engine using UV1.x, and smoothed using either a hard-coded angle or a user input one. AFAIK UE3 works like this. You’ll have to see how much control you have on engine side, if any.
Otherwise, probably not as fun to hear, you could re-evaluate some of your UV seam placement. For example the oblique seam at the rear of the creature could be eliminated or moved to have a continuous surface to match the flow if the topology.
good sculpt job by the way.
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