Mesh vs Sculpt LI 64x64 Mesh Terrain

[Drongle McMahon]

Thanks Gaia. I look forward eagerly to seeing that.

[Dominic Damiano]

Can one of you explain what that means and how it will help. I assume that it has to do with reducing verticies making more of them share a common side.

[Drongle McMahon]

Previously, and by default, Blender has contsructs vertex normals on the fly by using the face normals, for flat shading, or by interpolating adjacent face normals, for smooth shading. The latest version of Blender (2.74) has added methods to use and modify explicit vertex normals per (face+vertex).  These are called custom normals. One of the tools provided allows the copying of normals from one mesh object to another. This can be used to make the normals at the edges of a separated model the same as those on the joined model, which is more or less what we have been trying to do here,

However, so far the Blender Collada exporter only exports the old normals, nit the custom normals. So this facility can't be used in Collada exported directly from Blender. Gaia, who is one of the managers of Collada exporter development in Blender, has confirmed that future versions of Blender are planned to have the ability to export the custom normals. That will make solution of the normal-matching problem, the subject of this thread, much easier.

[Dominic Damiano]

I now understand this better. This will allow the split sections to appear seamless. Have you had any time to look at my steps and see if I would be able to use a height map and still achieve low LI results?

[Drongle McMahon]

Yes. Watch this space.

[Drongle McMahon]

There must be at least a million very different ways to do this. Of those I tried out, here is the one that seemed to offer best compromise between easiness and quality. Others will prefer different approaches. Experiment is the key. The LI could be a lot lower with more removalof redundant triangles, but that is left to the reader. The basic idea with this kind of height map is to concentrate vertices in the border where the height variation is, while reducing the redundant triangle count elsewhere. Also, the edges loops are made to approximately follow the contours of the slopes to avoid nasty triangulation artefacts that happen otherwise. These artefacts lead to over-subdivision to compensate, and resulting high LI. The high LOD mesh is also used for triangle based physics to ensure accurate walkability. To avoid excessive physics weight, it is therefore essential to remove small triangles, as done at several steps here.

1. Delete all objects; Object mode, top view {NumPad7}.
2. Set background image to heightmap; Size -> 32.
3. Click 0,0; Object > Snap > cursor to grid.
4. Add > Mesh > plane; Edit mode; Select all; {S32}.
5. Click [subdivide] 4xx. Set Wireframe view {Z} [Pic 1]
6. Select inside verts; Delete; Select all [Pic 2]
7. Move vertices {G, drag each} to surround raise area [Pic 3]
8. Mesh > Faces > Inset; Drag to inside flat area [Pic 4]
9. Select {AB} and merge at center {AltMA} to merge close vertices [Pic 5]
10. Add verts with LoopCut&Slide where needed, and nudge into place [Pic 6]
11. Select the bridging edges and use [subdivide] with cuts=3 [Pic 7]
12. Divide central ngon into quads; here using lots of alternating J and [subdivide] [Pic 8]
13. Manually decimate interior; here using alternating edge slides and remove doubles [Pic 9]
14. Remove some redundant edge loops [Pic 10]
15. UV map with Project from view (Bounds)
16. Add Displace modifier with height map via UV mapping, Strength to taste [Pic 11a]
18. Optional for flat base: Select outer edge loop, {SZ0}, move down a bit [Pics 11b-d]
17. UV map using plain Unwrap and adjust to fill UV area [Pic 12]
Notes: Last step is necessary for even texturing of slopes.
It would be easy to reduce LI further with more stringent manual decimation.
Imported with autoLOD, high LOD as physics, NOT Analyzed.

LI=24, dlwt=23.9, phwt=18.3

ETA: just noticed, the wrond edges highlighted in pic 6. The added ones are one step anticlockwise from these :matte-motes-dont-cry:

ETA: Here is a MUCH faster and nicer way to make the decimated middle: Just do a couple of rounds of Mesh > faces > Inset faces on the big central ngon, with a bunch of vertex merging after each, then some more redundant edge removal. Now LI=20, dlwt=20, phwt=13.4

Also, proper normal and spec maps make it better (if you use advanced lighting).