Ugly squares on sculpties.

I use Zbrush and the Wings3D exporter. Then I do a final smoothing in sculptypaint, but this problem is happening on this shape whether or not I use sculptypaint. Sometimes I get these squares that show with the shadowing. The squares disappear if I turn the texture on to full bright.

So far I have been able to avoid this by starting over from a sphere and re-sculpting the shape more carefully to keep it smooth. With this particular shape, I have not been able to avoid the squares. How can I get rid of them?

It's odd, but I can't really see any squares in your example.

I think you're referring to the gouraud shading of sculpties. Just by looking at this demonstration below of gouraud shading you can see the individual polygons.

http://en.wikipedia.org/wiki/Gouraud_shading

You could always try baking the shading into your textures from a higher resolution version of your model. This way you can enable full bright.

Thanks for the wiki post, looks interesting.

Full bright is not a solution. I sell my sculpties as full perm kits and I want my customers to have nice looking sculpties without the full bright.

Perhaps this image will be a better illustration.

Yep, I see them now

It's just the way gouraud shading works. It's not a bug or anything like that. You'll see the same side effect in other 3D programs that support that shading mode. It tends to stand out more on objects with a low poly count.

each vertex gets rounded and pressed in an integer range of [0..255] when the sculptmap is created.
This can move every vertex by up to [-0.5..0.5[ along all 3 axes, thats up to 1/255 th of the maximum prim scale along that axis and often visible.
This rounding can crate hills and bumps on a smooth spherical/cylindrical surfaces and even on a diagonal-but-not-complanar-to-local-xyz-planes surface.

Its a limitation due to very low resolution to save bandwidth.
To work around it you would have to move all meshes along a grid, then you see the exact result and the hill/bumps you will get (no rounding then), and you can try to smooth them while staying on the grid.

I've just done me some testing because I wanted to show that it had nothing to do with sculpties at all. You can reproduce the effect with a regular sphere. Especially if there is a local light present.

Set the sun to midnight and create a sphere with a medium grey color, then place a light close by and you'll see subtle ridges along the edges of the sphere's polygons. You can even see the LOD changes as you zoom the camera out away from the sphere.

So this begs the question - do you have a local light nearby?.

But like I say, local lights don't have to be present, they just help exaggerate a side effect of the gouraud shading.

Thanks for all the info. I figured out a quick work-around. I am accustomed to using a 64x63 sphere in Zbrush. I take my finished sculptie map into sculptypaint, reduce the resolution to 32x32 and hit the smooth button, then put it back at 64x64 for final smoothing. This reduces the visibility of the gouraud artifacts significantly to an acceptable level.

I'm so glad. I am making sculptie heads with beautiful photosourced texture "skins". The gouraud artifacts were ruining the effect.