#LW Spline Patching
5 messages in this thread
Hi. I was hoping someone may be able to help me. I've been working on a
project that requires the use of spline patching. Everything works out
fine up until I render the object (a plant). When I use shadow mapped or
ray traced shadows, the shadowing is choppy and you can see the triangular
polygons on the edge of the shadows. In some places where it should be
completely shadowed, some polygons are not shadowed at all. Anyone know
what causes this?
I've tripled all polygons as well as subdivided (smooth) them and it
doesn't seem to help. I also merged all points and made sure there are no
nonplanar polygons.
Thanks in advance.
Dave
Under the Lights menu, try increasing the shadow map size from 512 to
something higher, say 1024. This eats up a lot of memory so don't try
anything past 1500.
Joe Clasen
Joe's DB&G
Thanks for the reply. I tried increasing the shadow map size but it
didn't seem to help. After spending the better part of last night
dissecting the leaf to try and find the problem, I decided to just rebuild
it. That didn't do much so I did a some test renderings with different
lighting angles and found that the problem with the triangles in the
shadows only happened when the light source was to the side of the leaf.
It turned out that what I thought were "bad" polygons were shadows of
other polygons on the leaf. Let me explain how I'm building the leaf so
you can get an idea of what kind of headache this is giving me.
What I'm doing is loading a scanned image of a leaf into the background of
modeler and then using splines to build a cage of the same shape. After
bending the cage a bit to give it a more organic shape I patch it using
two-sided polygons so it can be seen from both sides. Afterwards, I make
sure there are no non-planar polygons and merge all extra points.
I've tried about every button in LW to get rid of this problem but with no
avail. The only solution thats worked is to use no shadowing.
I'm sure the three pots of coffee I've drunk aren't helping either.
Thanks again.
Dave
It sounds like an object problem to me, but be aware that when using
shadow maps, you can get strange results if you hit a polygon "on edge"
with the shadow map light source…
JG