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Rather odd issues with textures on OBJs...

reverendhammer_600dcd45e6reverendhammer_600dcd45e6 Posts: 3
in Daz Studio Discussion

I've been looking for arcade game cabinet 3D assets for an idea I had in mind. What's been 'officially released' in the various stores for Daz I've honestly been less than thrilled with. Plus I'd prefer to have actual game cabs for this idea anyway. Thankfully there's quite a few out there in other formats. But I'm running into a really weird issue with textures and I'm not entirely sure why. The items are all in OBJ format though I did try a few different paths to get them in that state. Which I'll explain in a bit.

So here's Ultimate Mortal Kombat 3 in Texture Shaded mode in the first image. Looks relatively OK. But when I go for Iray preview (and this does happen in full render as well) certain textures (especially on the control panel) get weird in Iray. And the result can even change if you change the perspective a bit. The Midway logo on the right hand side gives different rendering results. That's not the only thing I've seen do weird things like that. Multiple parts of the control panel, the marquee, and sometimes the side art will do that depending on the viewing angle. And I'm not sure why.

One thing I have figured out is that it doesn't seem dependent on the asset or how it eventually got into the OBJ format. I had another cab (Wrestlemania) that ran into similar issues. And the application source doesn't seem to have any bearing either. UMK3 was originally a Sketchup file and Wrestlemania was in 3DSMax. I pretty much run into this regardless of how I eventually got the OBJ version.

Any ideas?

 

 

umk3-1.jpg
1567 x 1359 - 717K
umk3-2.jpg
1563 x 1356 - 669K
umk3-3.jpg
1562 x 1356 - 795K

Comments

  • Richard HaseltineRichard Haseltine Posts: 102,308

    Odd results can happen when a non-square, four-sided polygon is split into two triangles for rendering - each triangle applies a different transform and the result s just the kind of distortion you see there. One thing you might try, though I'm far from sure it will help:

    1. activate the Geometry Editor tool
    2. With the model selected click on the problem polygon (may be easier in one of the wire viewport modes)
    3. right-click>Geometry Editing>Rotate Triangulation of Selected Polygon(s)

    If that doesn't help I think it may be necessary to rework the emsh in a modeller - though if I am along the right lines the existing mesh would be fairly simple.

  • reverendhammer_600dcd45e6reverendhammer_600dcd45e6 Posts: 3

    Thanks for the help. As you mentioned it didn't get far at all. I did a bit more research to see if there was maybe an easy way to convert everything to quads. 3DSMax has a tool to do it. Though when a friend of mine and I tried both the 2018 and 2020.2 versions of the Quadify tool there it made 3DS nope out. Bleander has a similar tool but I haven't tried it yet. My friend if better versed in 3DS than I am so they were going to see if they might be able to get things to a workable state.

  • PadonePadone Posts: 3,778
    edited February 2020

    Since opengl works fine it shouldn't be a issue with the model geometry. I mean bad normals are displayed in opengl too. It could be a shadow terminator issue that may happen in iray with strong lights and low poly geometry. If this is the case you can fix it by subdividing the geometry to get more polygons, be sure to subdivide without smoothing.

    Unfortunately the shadow terminator issue can't be fixed though some pbr engines (cycles) are better than others (iray) dealing with it.

    https://developer.blender.org/T68920

    https://wiki.blender.org/wiki/Reference/Release_Notes/2.81/Cycles

    Post edited by Padone on
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