Strange "overlapping" Why?

# 1 03-11-2002 , 12:36 AM

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1) There is nothing wrong with the placement of the objects here!
2) Its just that the surfaces seem to overlap (as seen in black in pic below), thus rendering as a black/dark surface!
3) This is not a problem when rendering closer!
4) So the objects isnt "really" overlapping.

I have to fix this for the rendering. Its the same result, of course with either poly or nurbs surfaces (I tried both out).

How can I fix this problem (besides moving the objects further away from each other)?

Last edited by undseth; 03-11-2002 at 12:38 AM.

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# 2 03-11-2002 , 12:46 AM

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I can't really see what's going on in that pic, but I would surmise that your projection is projected on both surfaces.

-Mike
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# 3 03-11-2002 , 12:55 AM

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The pic shows a lot of dark spots particulary on the left part.

This model is not textured.
99.9 % of the objects have the same basic shader.

I though this might have something to do with some kind of accuracy setting in maya, but I have no clue.

The model here is quite simple;

There is a nurbs (or poly, I have tried that too) sub -structure, like an encasing for the main shape of the left part, with... several poly objects as laid on top of this "main-shape" to act as details (like fuselage panels and such).

There should be no problem with overlapping surfaces, but somehow maya presents it that way.

I have noticed that when two surfaces overlaps each other, then maya renders these barely interceting surfaces as black. But I assure you this is not the problem here user added image

.

There is "plenty" of space between the different objects on this left part, shown on the image.

If I make a close-up-rendering, then the problem goes away, so this is the "best" pic to show this problem.

I hope this filled in some gaps.

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# 4 03-11-2002 , 01:00 AM

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Closeup

Anyway here is a close up, which renders fine.

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# 5 03-11-2002 , 01:01 AM

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Oh, so no textures involved.... ok.

Have you checked your normals? If they're all polys, have you tried combining them all together (if you can anyway)?

-Mike
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# 6 03-11-2002 , 01:08 AM

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hmm

The nurbs encasing has tiny normals (viewed in shaded mode)...
The poly version has long normals pointing "inwards" (!)

I guess the normals should point up and towards the light.

But how do I change the direction of the normals on both the nurbs and poly surfaces ?

I'll go look it up but feel free to post a reply, that would be kind user added image

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# 7 03-11-2002 , 01:26 AM

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Doesnt seem to be the normals!

I have changed the normals on the few relevant polygon-objects, but the problem hasnt gone away.

My right-part (the cluster of objects) on the pic, had correct normals from the start, but a new render shows even bigger oddities on that right-most part, than what was shown in the pic above.

hmmm?

I have checked most objects on the left-part, and the normals were correct with the detail-objects. It was only some of the "encasing"-poly-objects that had the normals the wrong way.

well well

Last edited by undseth; 03-11-2002 at 01:31 AM.

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# 8 03-11-2002 , 01:31 AM

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Hmm... strange. can't say I've seen such an issue before. Are you using 4.5 or 4.0? If 4.0, feel free to let me take a look at the file. I don't have 4.5, though, so someone else will have to take a look if you've got the new version.

-Mike
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# 9 03-11-2002 , 01:32 AM

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I'll go save, close and open the project again, and do another render!

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# 10 03-11-2002 , 01:48 AM

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nah...

I closed maya and opened the project again, but I got the same render-artifact, but the artifact went away when viewing from even further away. As shown below.

I GIVE UP for now user added image

...

I'll do a close up rendering, where these artifacts arent showing up and messing with my pics.

Last edited by undseth; 03-11-2002 at 02:14 AM.

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# 11 03-11-2002 , 10:33 AM

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Do you have dmap shadows turned on? If so, try to increase the dmap resolution and/or the filter size...

Kari
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# 12 03-11-2002 , 01:14 PM

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A solution :)

No depthmaps, its all raytrace, with one dir-light.

But I started doing some investigation work today...

I deleted everything on the other layers, besides these two shapes, as shown in the pics.

At some point during the last detetions, a new render showed no artifacts, where there had been so earlier.

But did not find out why this rendering-artifact occurred.
I have always taken comfort in rendering the objects shown on the screen and thus making them show up on the rendering (of course), but...

...now I found out that my outliner showed LOTS of "unknown" nodes, of various types.

...so I deleted the HUGE amount of exessive group-nodes and such, until the project was really cleaned up.

Although I dont know why the rendering-artifact appeared in the first place, they are now gone.

Maybe my computer couldnt handle all the action, or maybe I'm wrong.

Hopefully this can help you guys in figuring out why the r-artifact came about.

Some kind of "artifact theory" would be nice, if anyone knows about this, or have an idea of such.

:banana: :banana: :banana:

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