Shadow Problem; visible polygons

[monsoon3d]

strange thing,

first i would try using a different shader (e.g. blinn) if it´s caused by that.
or change your lighttype to something more directly :D like a directional or area light.
do your transparent objects cast shadows and are they visible in reflections ?
try tweaking the samples or recursion depth (performance of render globals).


let us know when you solved it, would be pretty interesting :) .

[Mr Majestic]

use mayas renderer and try using some nice raytracing and see if it does the same thing. It may also be your blurred reflections that you did. I havnt used mental ray in maya, but im sure there is a quality of shadows option in there, may need to put those up.

[gga]

What you are seeing is most likely a problem inherent to imprecissions in the floating point calculations. Your orange object is being incorrectly self-shadowed.

There are several ways this can happen. The 3 most common ones are:

a) Bad modeling. The object has both inside and outside polygons pretty much positioned at the same place (or worse, has two sets of polygons facing the same way one on top of the other). The result is that the inside polygons sometimes shadow the outside polygons.

b) Floating point issues with area lights. Maya has several ways of producing soft area shadows. These include:
- using maya's area lights.
- using spot lights with a soft shadow radius and several samples.
- mental ray's native area lights.
From those, only mental ray's area lights have some smartness in them that avoid bias issues. The others may see artifacts due to imprecissions, particularly if the soft area is too big or the triangles in the object are large.If you are using an area light, try switching to a normal spot light with no blurred shadows. If the artifact disappears, then turn on the area light setting in the mental ray section of the spotlight.

c) Your bump is doing funky things with the normals and the shaders you are using do not compensate for it. Basically, your bump map may be too strong so as to make the normals flip around. Try to turn off the bump map and see if the problem disappears. If it does, then apply it with smaller values.

[-Tj-]

Thanks for the suggestions. Turns out translucency was the problem. For some reason, mental ray doesn't like translucency. When it's removed, the object renders as it should. If I could, I probably could have used Maya Software instead (the artifact doesn't show when rendered with Maya Software), but two of the project requirements were render with mental ray and with Final Gathering enabled. I'm going to have to adjust the shaders to come up with a similar look without translucency. :(

I tried rendering it with different lights, different materials, and without bump mapping, etc. Translucency was definetely the culprit. Anyone know why? :surprised:

Here's the render as it is now. I'll post a new version after I get the shaders 'fixed'. Hope you like it. :)

http://www.theforeverproject.com/random_images/stilllifebefore.jpg

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