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Smooth flat surface glitch
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Smooth flat surface glitch // Archive: Tech Forum
Post by robert // Jan 20, 2008, 9:15am
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robert
Total Posts: 609
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I was making a die because I was kinda bored, and I noticed that no matter how I make it some of the flat parts become "holey" when I add SDS or Smooth Quad Divide it. When I copied the die one of them had no problems while the other retained the "holey" spot. Also if I move the middle point of the flat area in or out just a little bit like 0.001 then it's fine. This is all rendering with Vray by the way.
I attached the model if anyone would like to experiment.
In the first picture the problem can be seen, however in the second picture I moved the middle point of the area 0.001 units in and no more problems.
Does anyone one know why this happens? Or does VRay just not like flat areas being smoothed? |
Post by jamesmc // Jan 20, 2008, 10:34am
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jamesmc
Total Posts: 2566
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Hard to say without seeing the wire frame. |
Post by robert // Jan 20, 2008, 10:45am
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robert
Total Posts: 609
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I did attach the object, but heres the wireframe anyway (not smoothed)
Edit: there seems to be no problem when I use it in a scene, only when it's by itself. |
Post by TomG // Jan 21, 2008, 5:09am
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TomG
Total Posts: 3397
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The vertices that define the outside of the dots do not connecto the vertices that define the faces they are sitting in. This is known as a "floating vertex"
This can be problematic, eg when you export to other programs, or when applying SDS. Generally, you should not have a vertex "floating" inside a face but unconnected to the outside of the face.
Since tS will likely connect those up by itself when SDS is applied, the center face likely has some issues, as most of the square faces surrounding it will be altered in some way.
The thing about a floating vertex is that it can be hard for software (eg render engines, real-time renderers, modelers, SDS algorithms) to calculate just how the face is meant to be defined in space, as the surface has to go between many vertices all at once.
For using SDS, I would avoid such vertices as much as possible and ensure that any vertex is always connected by an edge to the other vertices on the face, leaving none "floating"
HTH!
Tom |
Post by TomG // Jan 21, 2008, 5:12am
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TomG
Total Posts: 3397
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Some more info, see attached image.
BTW, this may result in unwanted SDS effects - you have quite a lot of detai already in the mesh for the dots, they may work better just as squares and let the SDS round them out :)
HTH!
Tom |
Post by robert // Jan 21, 2008, 5:23am
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robert
Total Posts: 609
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The funny thing is that's not the problem, I had specifically engineered it so they would be floating because that way I can paint the dot and it stays round inside its box. If I were to connect it to its surrounding box it would pull away the connected vertices making it more blockish. Also when I made the dot with a box instead of the circle and tried to smooth it, it stretched somewhat funky. I had the dots done this way because it seemed to work best.
That isn't the problem though. For example load a cube on model side, head over to workspace and quad divide all sides 3 times. Use the map I provided and apply it with displacement mapping; there are still artifacts as can be seen, sometimes it happens in different locations like between the four etc.
There only seems to be this problem if I try and render it as a standalone object, however once I introduce other objects into the scene, it seems to disappear. So there isn't really much of a problem unless I want to render the object by itself. |
Post by jamesmc // Jan 21, 2008, 7:42am
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jamesmc
Total Posts: 2566
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Don't know if this will help you or not, but this is the way I created some die.
I didn't try the transparent die as booleans create special problems when things are transparent (shadows and odd reflections)
I made the die 4X4 polygons and then added .07 divisions to the edges as seen in the top image.
For the boolean sphere, I made it a 20 segment sphere and colored it black. |
Post by jamesmc // Jan 21, 2008, 7:44am
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jamesmc
Total Posts: 2566
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Next Part Die
first image
I then sized the sphere and placed them all around the die in their respective places, burying the sphere about half way down into the cube.
After all the spheres were placed (all sides of the die), I then subdivided the die twice before I did any booleans.
One does get some artifacts. Couple of things the spheres have to be exactly placed and another subdivision on the sphere and die may help eliminate any artifacts.
last image
final render |
Post by robert // Jan 21, 2008, 7:45am
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robert
Total Posts: 609
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Yeah that was one of the ways I had done it, but it kinda messes up when you add SDS and try and render, just like with the others. It doesn't really matter how it's done, if there are other objects in the scene it seems to work itself out. Thanks for the help though guys. |
Post by jamesmc // Jan 21, 2008, 7:55am
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jamesmc
Total Posts: 2566
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Will load the dice object in the garage if anyone wants it. :) |
Post by Mel // Jan 21, 2008, 7:59am
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Mel
Total Posts: 9
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Were is the garage. I want it. |
Post by robert // Jan 21, 2008, 8:00am
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robert
Total Posts: 609
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Were is the garage. I want it.
It's here:
http://forums1.caligari.com/truespace/forumdisplay.php?f=16
and I'll post mine there as well if anyone would like it. |
Post by Mel // Jan 21, 2008, 8:40am
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Mel
Total Posts: 9
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Many Thanks, Robert,
Very nice. I want to see what I can acheive with it using Vray. |
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