PDA

View Full Version : Perspective Camera Rendering Problem



Litebright
10-20-2008, 09:12 PM
I am having problems rendering a model with the Perspective Camera in LW 9.5.

I'm working with a submarine model that has subtraction boolean cuts in the hull to create flood holes. The sub model was built in LW 9.0. When I render the model with either the Perspective Cam, Advanced Cam or Real Lens Cam, the renderings all contain what looks like shadow cracks in the hull around the areas where some of the boolean cuts were made. This is caused by these areas not being totally smoothed out, as after the cut some of the joining vertices may have slightly shifted in 3d space. When rendering the same model with the Classic Camera, I do not see the shadow crack artifacts, instead the surface appears completely smooth. I've tried recutting the hull with higher detail geometry on a background layer to make the subtraction, but it STILL does not render properly with ANY camera other than the CLASSIC CAMERA.

Was trying to use the Perspective Cam to reduce render times and use Photo Real motion blur. Has anyone experienced this kind of problem before? Is there a fix for it?

Any help would be most appreciated!

Litebright
10-20-2008, 11:22 PM
Here are some images showing the problem area I am talking about..

Below shows the shadow crack above the flood holes as rendered by the Perspective Cam:
http://img444.imageshack.us/img444/7584/pcamcrack3ee2.jpg


Same frame rendered with the Classic Cam shows no crack:
http://img444.imageshack.us/img444/2946/ccamnocrack3em6.jpg

Area as seen in Layout in Shaded mode:
http://img504.imageshack.us/img504/8914/smoothshadenc6.jpg

Area as seen in Layout in Front-face Wireframe mode:
http://img504.imageshack.us/img504/2023/wireshadefc1.jpg

Area seen in Layout in Perspective wifeframe mode:
http://img504.imageshack.us/img504/3194/perspwirezv2.jpg

I can find no obvious misaligned vertices... Anyone know what might be wrong?

toby
10-20-2008, 11:53 PM
The geo doesn't look too bad, but whenever you have problems like this you should make the geo as kosher as possible, and that means no n-gons. Lots of renderers can't even read n-gons ( polygons made from more than 4 points ). The quickest-easiest thing to try is select the poly with all the holes in it and press shift+T, then see how it renders. Save a new version though, sometimes triangles don't look so good. Should be ok here though.

Litebright
10-21-2008, 12:20 AM
Thanks for the input Toby! Much appreciated. I will give the shift+T thing a try and make sure to eliminate any n-gons.

WilliamVaughan
10-21-2008, 12:44 PM
look for non-planar polys...that is probably it