Material definition in Zbrush and weird shadows on normal map

JamesLarden

Hey PolyCount, I recently posted this to 3D p&p but it's kind of getting lost there with no replies so I figured this is probably a more fitting place for it. I'm in the process of trying to sculpt a barrel. I want it to look fairly stylized but i'm having trouble defining the edges and I think i'm getting caught in the trap of my wood starting to look more like stone around the edges.


My biggest annoyance is that I can't get the edge wear right on the crevices between each plank, my plan was to carve out the lines and then flatten the edges to make them look worn, but I think I made them a bit too shallow and small width ways so when I tried to flatten the edges it was producing really ugly results.

Any advice is appreciated, I think what would help me most is if someone would be kind enough to share how the would go about sculpting a barrel in Zbrush. (Normally I don't think I would spend this much time on just a barrel, but it's for a college unit)

Also I am getting these weird black shadows on the normal map:




My first thought was that I needed to add more sections to the low poly barrel because there's a huge waste of space between the smooth metal ring of the high poly and the harder edge of the low poly. (Picture: ) Any help on this issue is also greatly appreciated.

Thanks in advance.

Bartalon

If I were sculpting a barrel, I would first create a base in Max/Maya the same way a real barrel would be constructed: separate pieces for each wood strip and metal rings. It will help separate the materials and make the gaps between the wood more believable.

Without seeing your UVs or smoothing splits, I would say you need to apply hard edges (and a UV split) on edges that you would consider a "corner" for your normal map to bake properly. Basically any two polygons that connect at more than about a 45 degree angle you probably want to make a hard edge and create a UV split. This thread explains it in more detail.

JamesLarden

Bartalon wrote: »

If I were sculpting a barrel, I would first create a base in Max/Maya the same way a real barrel would be constructed: separate pieces for each wood strip and metal rings. It will help separate the materials and make the gaps between the wood more believable.

Without seeing your UVs or smoothing splits, I would say you need to apply hard edges (and a UV split) on edges that you would consider a "corner" for your normal map to bake properly. Basically any two polygons that connect at more than about a 45 degree angle you probably want to make a hard edge and create a UV split. This thread explains it in more detail.

Thank for the reply, I just recently learned about polygroups so that should help a bunch, before I was doing it by scultping on the entire barrel as a whole and it was very painful to mask everything out haha.

This is my current uv tile for the low poly barrel, I assume it's pretty horrendous because I don't really know how to UV properly so tips much appreciated on that and thanks very much for the link.

Bartalon

For cylindrical shapes I usually just do a planar projection, cut a seam, then unfold (UV Texture Editor Window > Polygons > Unfold) with a horizontal constraint, then a vertical constraint. You can try using no constraints but it tends to cause the shell to pop diagonally for no reason.