Topology skewing on points

General
1

Hey Wrap3 Forums,

I’m currently trying to wrap a model to scan data however the topology is stretching along most of the points I’ve placed; see image below.

Any ideas why this is happening?

Regards,

Rashed

2

Hey Rashed,

Are you wrapping a basemesh to a neutral facial expression or a neutral expression to some different expression? If the former, the general suggestion is to use as few points as possible.

There parameters can also help to make the result better:

  1. Please increase Smoothness final parameter of Wrapping node up to 0.1 or higher.

  2. For such a dense mesh please increase Sampling initial (say to 10) and Sampling final (say to 1 or 2). It will also increase speed.

There two steps will make the result more stable and will prevent local noise on eyelashes.

If you are wrapping neutral expression to some other expression (i.e. producing blendshapes), the suggestion is to use evenly distributed control points all over the face. Some people draw evenly distributed markers on actor’s face. In several weeks from now there will be a release of Wrap3.3 in which a new OpticalFlowWrapping node will be added. It will allow to fit a neutral expression to other expressions using texture information and eliminate the need to use control points except for extreme cases.

3

Hey Andrew,

Thanks for the speedy reply; much appreciated!

I’m wrapping a 200k neutral base mesh to 50 different expression; blendshapes exactly.

Gonna re-run the wrap with the settings you’ve suggested; I’ll post the results once it’s done.

Thanks again

Rashed

4

If your goal is to create blendshapes, then I would strongly suggest using new OpticalFlowWrapping approach. In most cases it does not requires control points at all. It also provides result with almost pixel accuracy.

I will PM you with the details on how to apply for beta-testing in a minute.

5

Thanks for your help Andrew.

The settings you posted removed most of the warping; still a small amount there.

We have drawn black dots on the actor but I haven’t exported the colour information for the scan data yet so I was using the standard approach. Is is mandatory, when using blend shapes, to place the control points on the black dots of the model? This is my first time using blend shapes so it’s new territory for me.

Thanks for pushing us forward for the beta-testing; currently on a tight schedule to get these models finished so that’s a massive help.

Regards,

Rashed

6

Oh, I see. The approach I was using before optical flow tool was:

  1. To wrap a generic basemesh onto a neutral expression.
  2. Import the wrapped basemesh back into photogrammetry software and re-project textures from original photos. Both RC and Photoscan can do that.
  3. Wrap the neutral basemesh onto each expression placing control points according to marker positions on both textures. It usually took me 150-200 points per scan which is was a big pain.

With the new approach it can be done almost fully automatically with better accuracy than if you place 200 markers by hand.
If you are in a rush, please contact me by Skype and I’ll help you to get familliar with the OpticalFlowWrapping tool. It’s really a huge time saver.

7

Really kind of you, thank you!