The section of TerreSculptor that is currently under development is a major re-working of the mesh plane importing code.
This currently applies to the .obj and .stl file formats, and will be applicable to all future mesh grid plane import formats.
The two major shortcomings of this section in TerreSculptor included fixed-vertex-spaced-and-perfect-vertex-aligned grid planes only, and single threading.
This section of TerreSculptor is being enhanced to support imperfect non-aligned mesh grid planes, and full multi-threading.
Mesh to Heightmap
The big issues with importing and converting grid plane meshes to heightmaps are:
1. The vertex list may be in any random order, it may not be ascending ordered row-column or column-row.
Imagine trying to read in a picture where all of the color pixels were randomly scattered throughout the file, and you had to sort through and re-order all of them just to see the image.
Instead of this:
0,0 0,1 0,2 0,3 ...
1,0 1,1 1,2 1,3 ...
2,0 2,1 2,2 2,3 ...
...
You have to deal with this:
947,254 9,273 127,835 ...
395,528 46,29 623,784 ...
...
2. The vertex XY grid values may not be aligned.
In other words, all of the row and column vertex values may be off from each other by any amount from a small decimal value to a small percentage.
So even if the vertices were in an ascending ordered coordinate set, the coordinate values may not be identical.
So you have to deal with this (or worse):
0.001,0.062 0.001,1.053 0.021,1.998 ...
1.000,0.028 1.009,1.016 1.001,2.011 ...
2.001,0.015 1.997,0.995 2.026,2.059 ...
...
3. The vertex list may be located anywhere in 3D space.
The grid plane may not be centered in the 3D world. The mesh exported by the user may be located anywhere in any combination of -,-, -,+, +,-, or +,+ space.
4. The grid plane may be any extent size.
Even though the grid plane may be a size such as 512x512 vertices, the spacing between the vertices can be virtually anything, from 0.001 or less to 1,048,576 or more.
And possibly a mix of negative and positive coordinates if the mesh is offset from origin overlapping across various world axes.
5. The grid plane Z vertex range may be any extent size.
6. And to make matters even worse, some software creates grid planes with random extra rogue vertices along the edges of some of the triangles or quads.
This completely throws the vertex XY coordinate counts off, the vertex spacing value, etc., making conversion a real chore.
Improvements
To successfully extract the equivalent heightmap requires a number of specialized algorithms to derive the pertinent data from the vertex list.
In addition to improving the mesh grid plane importing capabilities, the mesh importer has also been thoroughly multi-threaded. The maximum number of available threads (up to 8) are put to use in each algorithm section.
With the improved algorithms and multi-threading, what used to take approximately 2:12 (132 seconds) to import a 512x512 .obj file now only takes about 12 seconds for a messy grid plane mesh and less than 3 seconds for a clean grid plane mesh (on a i7-2600K workstation with 8 threads).
Can it still be broken and fail to import correctly? Of course, if the source grid plane mesh is badly distorted and no longer resembles a grid plane. That is where a toposurface conversion tool is useful.
Future
Although the updated mesh grid plane to heightmap class supports multi-threading, further improvements will be analysed for their benefits, such as a finer granulation thread-pooling system which may squeeze out another 10-15% performance.
Upcoming mesh file import/export support is planned for the following file formats:
.3ds import (Autodesk 3D Studio), .asc (Autodesk ascii), .ase import (Autodesk Scene), .dae (Collada), .dxf (drawing exchange), and .ply (Poly).
There is no solid release date for all of these formats though, so do not count on them to be available in the short-term until announced.
The updated mesh to heightmap conversion class has also been written to allow for a future feature of converting toposurfaces to heightmaps.
Toposurfaces are irregular and often triangle-optimized topographical surfaces. They are commonly used with other AEC/CAD applications for simplified low-poly site landscapes.
The future TerreSculptor feature for converting toposurfaces and pretty much any other irregular mesh will be through a new "Mesh Conversion tool" on the Tools menu.
This tool will be a full interactive 3D viewport with controls and settings for allowing what is essentially a draping or skinning of a heightmap over the irregular mesh.
The Mesh Conversion tool is currently targetted to be available in version 1.5.
An example of an optimized toposurface mesh which would require special conversion.
-eol-