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Vue F.A.Q (Last Updated: 2024 Dec 13 6:58 am)



Subject: Why am I getting this grit on my renders?


Phantast ( ) posted Thu, 08 December 2005 at 4:21 PM · edited Mon, 23 December 2024 at 12:28 PM

file_310717.jpg

I've had this problem a few times, and I just don't understand what's causing it. In these three shots, all that is changed is that the camera is pulled further back in each shot. In each image there are nasty black speckles, but the area affected increases as I move the camera. Weirder still, the speckles cover the back wall and objects on it, but not the sky viewed through the gap in the wall, nor the side walls. A bit of the floor is affected. The lighting is just a few standard point lights, no soft shadows or anything like that. As I move the camera around, or the room around, the problem gets better or worse in ways that I don't follow. What IS causing this?


Phantast ( ) posted Thu, 08 December 2005 at 4:45 PM

Some further experimentation - it seems to be something to do with the mesh object (originally an .obj file, imported via Poser, because otherwise Vue doesn't read the material zones). If I go to edit object and deselect "double-sided mesh" the speckles go (but so does part of the mesh). On the other hand, if I change the lights, or replace all the materials with flat white, it has no effect.


wabe ( ) posted Fri, 09 December 2005 at 1:06 AM

I have that when i use lights with softness - especially when that softness is too high. If you have that in your scene, try to reduce that softness - for tests - to zero and look again. And then increase slowly. My experience is that all over 10 can be critical with imported Poser meshes.

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Phantast ( ) posted Fri, 09 December 2005 at 1:20 AM

I have seen that with softness also, but in this case the lights are all hard. It is clearly something to do with the mesh, because of the fact that changing it from being double-sided removes the speckles (but loses part of the mesh). It seems perhaps to be a bug in the Vue render engine.


wabe ( ) posted Fri, 09 December 2005 at 1:23 AM

have you tried to "bake to polygon?" Maybe worth trying in this case. I think of all options that maybe change something in the model structure. Welding, baking, ...

One day your ship comes in - but you're at the airport.


Cheers ( ) posted Fri, 09 December 2005 at 6:28 AM

"It seems perhaps to be a bug in the Vue render engine." I'm not so sure...bet any money that it was a boolean operation that created the square opening in that wall and/or used somewhere in the creation of the object. Booleans are evil grrrrrrrr :P ;) Cheers

 

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Phantast ( ) posted Sat, 10 December 2005 at 12:09 PM

I've tried bake to polygons and it doesn't work. I can well believe that a boolean somewhere in the mesh may be the culprit, but surely the fact that a boolean was used in the creation of a mesh should not make it render funny unless there was a problem in the render engine. I've rendered the same mesh in Bryce often enough with no problems.


Phantast ( ) posted Sun, 11 December 2005 at 3:27 AM

Well, I tried exporting the mesh from Poser as a 3ds file, taking it into Rhino, exploding it, removing the end wall, replacing the wall with a plain box, creating a new obj file, taking that into Poser and thence into Vue, and lo and behold the problem still occurs. It doesn't seem so bad as it was before though. I think the trouble may not be with booleans but meshes with no thickness. That end wall seems not to have been a boolean, because the sides of the opening were individual surfaces.


jc ( ) posted Mon, 12 December 2005 at 1:38 AM

What speckles? I don't see any speckles. Better clean your monitor screen. Seriously though: (Kinda grasping at straws here since you've tried the obvious): Maybe reverse the normals? Try more or less poly edge smoothing? More ray bundles in the render? Pretty good puzzle ya got there :o)


Phantast ( ) posted Mon, 12 December 2005 at 5:39 AM

I've tried everything that's possible within the "edit object" window. Yesterday I had the same problem with a completely different mesh that I made myself. One part of the mesh was a boolean (a box with another box clipped out of it) and that part of the mesh object was heavily speckled - much worse than in the examples above. When I split the object by materials, the speckles vanished. With the mesh shown above, splittling by materials has no effect. It's very weird, and I say it's a bug. It just shouldn't happen, and it doesn't in other render engines.


jc ( ) posted Tue, 13 December 2005 at 6:18 PM

Did you submit a ticket on the e-on site. Sounds like you've tried all the obvious stuff. Guess you have the latest display card driver, with the latest Open GL drivers and the latest Direct-X?


GPFrance ( ) posted Thu, 15 December 2005 at 8:30 PM

I got those speckles, too. Mostly on procedural ciment or mortar surfaces : I wanted to reproduce the grain of the surface, so I pushed the fractal generator in the editor, plus the final bump size, and scale. Horrible results, mostly on surfaces which nearly face the cam. Annoying when animating : those speckles flicker ! Can't show those clips. Pushing up the number of ray reflexions only changed the time for rendering, and gave nicer reflexions of those speckles in the window panes. When I turn down the fractal generator to medium levels, things get better, but the texture won't look like I wanted it to. I thought, kind of untrapped overflow or division by zero, somewhere in the bump calculation part of Vue. Perhaps I should try bitmap bumps for such surfaces ?


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