Hi Zed. Thanks for getting back to me.
Replies to your points (numbers don't relate to your numbers):
1. The vertical axis in Blender is Z by default, so normally objects imported into SL/OS have the same orientation. This has caused problems when I've made objects for Unity (with its Y vertical), so it's actually useful to me that it's that way for OpenSim and Blender.
2. The sides should all be equilateral. In your picture, it looks like you're viewing it from along the Z axis, and the visible face is not orthogonal to the camera. It looks very similar to this view (orthographic, fixed to Y axis):
where if I orbit the camera upwards (vertically), I get this:
If your view isn't like that, then it looks like the object has been distorted somehow. Is it possible to measure the edges in Maya? They should all have exactly the same length.
3. You're quite right - the Sketchup model has duplicated vertices, which I hadn't noticed.
However, I'm no longer using that model anyway - I created a new tetrahedron by deleting vertices from a cube, and that has only the 4 vertices:
That model also exhibits the shifting origin when I apply (freeze) the rotation. So unfortunately, the extra vertices are not the culprit.
4. The size of <3.048;3.520;2.874> doesn't surprise me - I wouldn't expect an imported tetrahedron to have equal values in the scale. It's made of equilateral triangles, and the length of one side of an equilateral triangle is not equal to the perpendicular distance between the centre of that side and its opposite corner (the Pythagorean theorem, aka "the square of the hypotenuse is equal to the sum of the squares of the other two sides").
If you like, I can upload that new tetrahedron somewhere, although it's probably just as quick to make one from a cube anyway, like in this tutorial:
https://www.instructables.com/id/Create ... -Inventor/.
I would be eternally grateful if you were able to to do that, and to rotate the object such that one of the sides is on the same plane as the floor, and that one of the edges of that side is parallel to one of the horizontal axes. If you can do that and keep the object origin at the centre when exported to DAE, that would be a tremendous help. From there, I should be able to UV map it in Blender, so please don't worry about that (the orientation of the UV maps, and hence the surface binormals, is critical to our application, and I'd need to experiment to get that right).
Thanks SO much, Zed. You're a gentleman!