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View Full Version : Rendering Glitch: Geometry disappears.


Drublic
02-02-2005, 07:29 AM
I've been trying for about a day to diagnose and fix this problem and I can't find what is going on.

I have a very simple scene with:
6 Directional lights
1 Point light
3 spot lights

The objects are polygons.

Rendering Settings:
3D Motion Blur Production
Highest Quality

Here is a screencap:

http://img153.exs.cx/img153/4253/screencap015cw.th.jpg (http://img153.exs.cx/my.php?loc=img153&image=screencap015cw.jpg)

Here is the rendered Result:

http://img146.exs.cx/img146/4690/glitch016xx.th.jpg (http://img146.exs.cx/my.php?loc=img146&image=glitch016xx.jpg)

The trim on the right wall disappears, the ceiling disappears and part of the right wall disappears.

I turned off each light individually and it made no difference.

I rotated the camera to see if the artifacts would show from a different angle and they didn't.

The camera is keyframed but stationary (in case I zoom in or something, the camera will pop back to place)

Deleting the keyframes made no difference.

If I keyframe the camera to rotate, the artifact does not appear on the first frame.
If I keyframe the camera to strafe (move left to right), the artifact appears.
If I copy the first Keyframe to the end and set tangents to flat, the artifact appears.

What is going on??

I appreciate any help or suggestions. I'm reaching my wit's end.

Thanks to ImageShack for Free Image Hosting (http://www.imageshack.us)

Jozvex
02-02-2005, 08:23 AM
Is the camera just on the inside of a wall? If so the renderer might be having trouble determining what it can/can't see.

In that case you could move the wall or camera. Or maybe it's the clipping planes?

Drublic
02-02-2005, 03:26 PM
Thanks for your suggestions, Jozvex.

The only walls are the ones you see. That is, there is no wall that the camera is in front of or behind besides the ones that are visible in the screenshot. So I don't think that is the problem.

I have adjusted the clipping planes so that they are Near: 0.01 and Far: 10000 and it still makes no difference.

Any other ideas?

floze
02-02-2005, 03:43 PM
Sounds like a motionblur problem. If motionblur is on, mentalray retesselates all of your objects, and maybe you have some polygons which mr doesnt like. Try to triangulate your whole scene before rendering.

Drublic
02-02-2005, 04:12 PM
Thanks, floze.

Well, triangulating did not help, since I am not using mental ray, but it seems like motion blur is the problem. If I turn it off, it renders fine.

I checked the documentation and it says that Maya has problems rendering "Complex backgrounds" with motion blur if they are stationary, and that I should render the foreground and background separately and composite them later.

This seems entirely unnecessary to do for such a simple scene. I'm wondering if changing motion blur settings might help. I have no idea where to start, though.

floze
02-02-2005, 04:18 PM
Thanks, floze.

Well, triangulating did not help, but it seems like motion blur is the problem. If I turn it off, it renders fine.

I checked the documentation and it says that Maya has problems rendering "Complex backgrounds" with motion blur if they are stationary, and that I should render the foreground and background separately and composite them later.

This seems entirely unnecessary to do for such a simple scene. I'm wondering if changing motion blur settings might help. I have no idea where to start, though.
Have you set the mblur to exact or linear? I'd leave it on linear unless you have shape deformations. Linear takes the object's tranformation only (position, rotation, scale) into account.
And, compositing the background later is in most cases better than doing it all in one.

Drublic
02-02-2005, 04:47 PM
Have you set the mblur to exact or linear? I'd leave it on linear unless you have shape deformations. Linear takes the object's tranformation only (position, rotation, scale) into account.


Those options do not appear for Maya Software rendering. Either that or I can't find them. They do appear in Mental Ray, though.

In any case, I was racking my brain trying to figure out a way for the background or camera to move a little so that the motion blur would not freak out and as always, the most obvious answer is staring at you right in the face:

I unchecked the "motion blur" attribute for all the walls and stationary objects and it renders fine now. :D

Thank you for all your help. Sometimes all you need is for someone to point you in the right direction.

markbones
02-03-2005, 01:27 AM
Can you post a wire of just these 2 surfaces/polys? How are these 2 polys subdivided? Sometimes if Maya cannot see enough sides of a face it will not render the object - if motion blur is on, once the camera starts moving you'll see them in the render, but if the camera is stationary, zippo. If the walls are simply one big face, try subdividing them a few times so you are able to see multiple edges/faces from the camera view. Make take a few divisions. Just an idea.

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