I have an alembic file that I’m tracking certain vertex positions over time on.
In this particular example, the vertex numbering of the model changes quite often, and the original chosen vertex that was being tracked changes to a different location, so I’m looking for a way to ‘estimate’ where it would have been based on the last known 2 or 3 sets of x,y,z positions. At that point, I can take the ‘estimated’ position, and search for the nearest vertex to continue tracking.
Any thoughts on how this would be done?
I’m pretty novice at this, so any detail would help!
Thx.
Mike
Oh, is it a game “Guess where the third one is hiding”?
But on a serious note, please explain why we need to “guess” instead of simply taking it from the file. Usually, the information in the file is straightforward enough.
(it would be helpful if you posted the file you are trying to read)
Let’s say it’s vertex id #1 that we are tracking, and it’s at the right shoulder of a 3D character for the first 30 frames.
With this particular alembic file structure, the vertex ids change over time. So, the vertex id #1 that was at the shoulder at frame 30, is now located at the ankle of the foot at frame 31. For whatever reason, there are a different number of polygons and vertexes in this file at frame 31. It could be that it’s a moving character, and things have been optimized, but the point is that the new vertex id number on the right shoulder is different than a frame before, and I would like the software to ‘predict’ as best it can what new vertex id is located where the old vertex id ‘should’ have been.
So, I’m storing the x,y,z positions in an array, and have already figured out when the change is going to occur by a simple vertex count/frame method. At that point, I know I need to start tracking the different ID number at frame 31…I just want to see if it can be chosen automatically based on where the last good vertex was, and then choosing the closed vertex to that location.
Hope this helps.
Sorry…forgot to add that I can’t post the file right now due to a NDA I’ve signed.
According to what you say, does this mean that each frame can be a different mesh in topology? (different number of vertices, faces, different order of vertices in faces).
Yes. It’s from a system that can do a live capture of a subject – turning it into an animated 3d mesh. So the mesh changes in both vertex count, and numbers of polys, if needed, on a frame by frame basis.
It’s then exported as an alembic mesh object.
I’m currently selecting a vertex I want to track, and then advance to the next frame that I know the mesh changes, and have to select a new vertex that is as close as possible to the last ‘real world’ location (meaning the shoulder point I mentioned before).
Here’s a file that may help. It’s in both a text format and excel format.
It shows the manual selections I’m doing, and time (marked by the ‘Y’ in the change column) the mesh changes.
So, at frame 3, I would like to use the data from frames 0, 1, and 2…to predict where it will be at frame 3, where the new vertex is needed. I would then run a ‘get closest vertex’ function that I have to find the real, new vertex closest to that prediction.
Alembic Sample.xlsx (17.7 KB)
Alembic Sample for CGS.txt (7.4 KB)
No… it can’t help in any way.
I assume we’re talking about some 3D scanning?
As far as I understand, it’s not about some kind of real-time solution. It’s more about preprocessing to make the mesh deformation data consistent from frame to frame, right?
No, trust me.
Real time capture of live talent.
Here’s a link to the hardware used:
I’m asking about what you want to do with it, not how it’s done. I am quite familiar with the technology described above.
You’re trying to explain your process, but what I want to know is the ultimate goal you’re aiming for.
As I understand it, you want to achieve the goal of creating a “constant” mesh that preserves its topology during deformation. There are two main tasks involved in this: first, building the “constant” mesh, and second, generating morph-targets for traditional morph-target deformation.
Additionally, there is a potential extension of the task, which includes generating or optimizing the skeleton for the “constant” mesh (optimal bone placement) and calculating the skinning weights.
You are now working on a “constant” mesh… Am I right?