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Thread: Render glitch.

  1. #1
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    Render glitch.

    I was rendering this paw print and no matter what angle or light setup I have there still appears this line at the bottom. I have lightwave 8.5.

  2. #2
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    well a higher res version would prolly help.

    from what i can see here it doesnt look so much like a render glitch as a crease or some other anomaly in the mesh... how about a wireframe?

  3. #3
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    Here is the object file.

    http://www.megaupload.com/?d=4DXAPKH7

    Here is the hires version

    Last edited by Muggin; 06-02-2006 at 11:13 PM.

  4. #4
    The Real Homestar. Intuition's Avatar
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    Won't let me download. Can you zip it and just attach it to your post here?

    It looks like you have some polygon face issues.
    -----------------
    KC

  5. #5
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    You have to let megaupload wait for 45 seconds before you can download, sometimes there might be an add in the top right hand corner that blocks this timer, just click the X and you should see the countdown to the link.

  6. #6
    Professional ConfUser VoltisArt's Avatar
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    I don't much like the odd ul/dl service...but as to the model:

    The (inverted) "U" shape in the primary face of the paw is the problem. LW doesn't like rendering single polygons with such inside corners, especially when smoothing is involved. This model is overly simple relative to the result you want. I see that you're using the surface smoothing for your effect, but this is what's giving you the trouble.

    Your best bet is to redesign the model from your original outline shapes. Bevel several times instead of once per side, giving yourelf a nice smooth profile in Back/Right views. Rely on the shape of the model a little more, rather than just the smoothing angles. Set the bevel Edges to Inner.

    Example:
    First bevel, up 2", in 0.5". Second bevel, up 1.5", in 1". Third bevel, up 1", in 1.5". Last bevel, up 0.5", in 2". This set will give you a quarter-circle profile, 5" high and 5" in from the edge. Experiment with the numbers until you get the desired sweep. (You might want higher or lower insets to bring the final inside edge closer to the middle of the shape.) It's much like drawing a crude circle or oval on grid paper, by crossing selected points. The end result will accept any smoothing you want to do, much more beautifully.

    Something to also try: Consider splitting the final face polygon in two halves, left and right. (Using the top and bottom center points.) Each half will be easier for the render engine to understand, but it also might throw a bug into the overall smoothing. Worth a try, to find out what looks best.

    Your toes look fine in your render, but I'd recommend giving them the same treatment you do on the paw pad, at the same angles. Consistency is usually the best plan. I'm noticing some similar distortion of light across them, in Modeler.

    As an alternative, you could work in spline meshes with real curves, but based on what I see in your model, this is probably the simplest solution. Good luck!

  7. #7
    Professional ConfUser VoltisArt's Avatar
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    Faster but less customizable option:

    Explore the Rounder tool. Begin with a block base of your design, extruded from the original outline to the final height you want. Select the front/back face polygon only, not the sides of the object. This will round over only the top & bottom edge. You can also try selecting (or not selecting) the entire thing, but your end result might be overly complex, rounding what's already pretty smooth.

    Play with the Rounding Polygons and Inset. you probably only need 3-6 polys to define your edge, otherwise it will render looking completely flat and destroy your specularity effect.

    The downside to this is no ability to make an oval profile if you want. I still usually prefer the bevel tool because with it, I know exactly where the polygons are going.

  8. #8
    The Real Homestar. Intuition's Avatar
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    Ok, this is a simple case of trying to make the top surface look round when it is flat. Or if you wanted it flat but wanted the sides round/smooth looking.

    In either case you have to adjust the smoothing angle in the surface panel. At 89.9 it tires to smooth over the flat surface at render time and will create tripled polygons on the flat surface.

    So, either you want a flat face with smooth sides or you want an entirely smooth object in which case you have to model the geometry a little smoother so that even a low smoothing angle can be used but still get a nice round surface. This is best achieved with meta nurbs.

    You want one of these effects in the look?

    Top one is your object with a low smoothing angle setting in teh surface panel. It keeps the bevel hard edged but allows the faces along the side to smooth. The lower left is the same idea only I have meta nurbed the sides and left the front face flat. The sides are completely rounded but the face still has a flatness to it.

    Then I tried the logo in meta nurbs starting from scratch. The meta nurbed object is smooth all the way around. Left one.
    -----------------
    KC

  9. #9
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    Wow, thanks for all the help you guys. I thought I would get at most like two responses with limited helpfullness. Thanks again.

  10. #10
    The Real Homestar. Intuition's Avatar
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    I can zip the files if you want them.
    -----------------
    KC

  11. #11
    Newbie Member Pe6r0's Avatar
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    for future reference:

    Quick fix I always do to solve such issues that generally come up with smothen textures : Triple polygons! It also helps sometimes to temper with the smooth threshold

    in case of a subpatch use Fixpoles

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