I'm expanding the vanilla tile sets as part of my dungeon overhaul and I'm running into some issues with seams. Here are the screens:

http://www.truancyfactory.com/images/misc/newCaveTile02a.jpg

http://www.truancyfactory.com/images/misc/newCaveTileInGame.jpg

My understanding (limited as it is) is that this has something to do with the normals. The the verts all line up, the textures are mapped pretty much seamlessly (easier to tell from the floor), the vertex coloring is pretty close to a perfect match but I'm still getting this really harsh shadow/edge along the seam between the tiles. Can anyone explain why these seams occur and how to fix them in noob-friendly language?

I'm using Blender to create the tiles.

Ok, used my Google-fu (and polycount) and figured out how to solve the lighting issue. I created a new tile from scratch using the new technique. The tile is a bit of a rush-job, so there is a bit of texture stretching and the vertex painting isn't perfect but the lighting issue has been resolved. Vide:

http://www.truancyfactory.com/images/misc/newCaveTileFixedLighting.jpg

I got the most benefit from reading a post by Erstam from 2004 at the Psychodog Studios forum about how he fixed the seam issue with the Morrowind version of Better Bodies. Can't post directly to the thread b/c it contains advlt content, but it's there if anyone wants to understand the problem with mesh seams better. Essentially, it's caused by having overlapping vertices with differently angled normals. I got around the problem by adding another edge loop around my tile that butts against the vanilla tile and making sure that none of these added polys were moved or rotated. Since the vertex normals are the same, the lighting issue disappears. Seems to work so far, anyway.

One of these days I'm going to write a tutorial about all this!