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  1. #1
    Join Date
    Jul 2009
    Posts
    86

    Mysterious Blackhole In Model

    Hey all, been a while. Decided to start work on a new model to take a break from the max fundamentals class. It's a 2010 Chevrolet Camaro, which I'm going to then transform into a mockup of a 2010 Pontiac Firebird I found on the internet.

    But a problem has emerged, as always with 3d modelling. If you look at the front bumper, you'll notice that I've cut the air intake's chamfered edge to the middle of the above face, cut out to the end of that face, then from the middle vertex created a cut to the centre. This is to stop a 5 sided face forming. Now I've done this before, but it's never done this. When the meshsmooth modifier is applied, the vertex suddenly becomes a black hole, sucking all other edges and vertices around it into it's sphere of gravity. Or something like that. Basically it's made a star, and that doesn't look very good in the render.

    Does anyone know what's going on here? I've checked weight and creasing for that edge, and that vertex, and both are default.

    Editable Poly screenshot >> http://mademan033.deviantart.com/art...WIP1-152501080

    Meshsmooth screenshot >> http://mademan033.deviantart.com/art...wip2-152501252

    Quick render (out of date file) >> http://mademan033.deviantart.com/art...10-2-152023668

  2. #2
    Join Date
    Nov 2005
    Location
    UK
    Posts
    402
    I look at those images and can't think of any other reason than some sort of overlapping geometry. Go through each of the vertices in the area surrounding it and pull on them to see if any errors become apparent. try and select all of them and click weld. otherwise delete those polys and recreate the geometry. You could also switch off isometric view in the meshsmooth to get a better idea of what's going on.

  3. #3
    Join Date
    Mar 2002
    Posts
    7,120
    Just a guess but your black hole is not really a black hole but rather the face normal has flipped on you.

    My guess is you created the one side and instead of using the symmetry modifier you instead used the mirror tool to flip the object from one side to another. Doing a mirror copy this way tends to turn the object inside out like turning a sock inside out and although the surface is displayed and rendered normal, more so with force 2 sided turned on, the internals will read the face normal as facing the other direction.

    With the newer versions of 3ds Max the default is to show backface cull so what you’re probably seeing is the black that is the back of the face.

    What you can try is use the reset Xform in the utilities and that will usually flip all of your normals into the right direction, and in most cases turn your car inside out, which you can then flip every thing using the edit poly flip.

  4. #4
    Join Date
    Jul 2009
    Posts
    86
    Sorry to lead you off in the wrong direction Frankie, but the "black hole" I was referring to was a metaphorical one. If it were a flipped normal, I'd have spotted it in 5 seconds.

    If you look at the screenshots, you'll see that the quadrangulated geometry on the bumper bar is giving way to circular triangular geometry in the meshsmooth. Even the hard lines that form the square of the bumper are being drawn in towards this center vertex. Deleting the faces resolves this, the outer faces square off again, but recreating it recreates the problem. Perhaps it's just that the isoline covers too many direction changes?

    I may have to adopt a more layman modelling technique, but I'm not convinced that that's the problem, and it would be inconvenient to dissallow cutting off edges to avoid having to connect a ring of edges around the entire car body.

  5. #5
    Join Date
    Mar 2002
    Posts
    7,120
    Hummm ok just to throw out another possibility a Poly object will not weld across co-sided edges. Think of a T shape object where the plane of an object crosses the center to create the T.

    This would explain why the meshsmooth is pulling a part at the edge.

    You can check this using the STL modifier that will show any open edges.

    If that is the case switch the object to a mesh object as the weld will weld everything and anything, including double faces.

  6. #6
    Join Date
    Jul 2009
    Posts
    86
    yes, I know this, hence my first port of call was to just tug at the vertex, but it's solid geometry.

  7. #7
    Join Date
    Jul 2008
    Location
    New York
    Posts
    527
    Just a suggestion, but maybe try ring connecting a new edge loop near the area in question. Sometimes there's just not enough geometry in an area, and meshsmooth can react poorly unless more detail is added.
    See my 2d artwork at www.thearthound.com

    "If you don't learn patience, you will never have the patience to learn."

  8. #8
    Join Date
    Jul 2009
    Posts
    86
    Yeah, I'm going to give this a try, and I'm going to move the edge ring that it's connected too away, and cut in a completely new one at the same time. Not elegant, but should work.

  9. #9
    Join Date
    Jul 2009
    Posts
    86
    Actually, looks like the solution was quite simple - just double inset the lower air intake faces first. I've also inset the faces around the fog light, to isolate its changes. Which was strange, because even after deleting the entire series of faces at the front, another problem emerged, a strange lip where two edges were welding together in the mesh smooth, but again there was no creasing or weighting in that area, and the symetry weld was off. But deleting the area and starting again worked this time? ~.^

    Thanks for everyone's input though, I'll hopefully have the next post in the 'Work In Progress' section, rather than the 'It's broken' department. Back to work I go

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