Forum: Poser Technical


Subject: How are the coordinate directions for subdivision morph deltas determined?

odf opened this issue on Dec 21, 2021 ยท 11 posts


odf posted Thu, 23 December 2021 at 4:02 PM

adp001 posted at 10:24 AM Thu, 23 December 2021 - #4432310

How I proceeded:
First, I loaded the standard prop "one sided square" into Poser. This consists of only four vertices that form a rectangle. I set the prop to subdivision level 1. Then I took Poser's morphbrush and moved the upper middle vertex (generated by Sub-D) to create a morph called "test". With "save binary" turned off, I saved the prop. I loaded the result into a text editor and searched for the entry "test". There I found this:

That's more or less what I did for my experiments. I create empty morphs from within the morph tool and save the CR2 with binaries turned off. Then I set the subdiv deltas to some defined values, load the result into Poser and see where the vertices go. I've also exported OBJs of the mesh with and without the morph to verify that the first delta direction is the normal.

The remaining big problem is to figure out how the u and v directions are computed. From visual inspection (on Antonia low-res) they seem aligned with the texture u and v but they are not generally orthogonal to the normal direction. Without knowing the exact method for determining those directions, the morphs will be off wherever the surface is not completely flat.

If the directions are computed on the base mesh and then interpolated (rather then recomputed from scratch) for the higher subdivision levels, one could potentially just take the measurements once for each mesh and then feed that into the script.

ETA: I hadn't tried to save just the prop. It's good to know that that also works.

-- I'm not mad at you, just Westphalian.