UV Unwarp

[Hao Yu]

Hi, 

I am a beginner in 3D Face Morphable Model, and have some problem. Could you give me some answers?

1. How to extract texture or albedo from an 2D face (an 2D image)?

2. How to do UV unwarp? In my opinion, the UV unwarp is to extend the texture from 3D model to 2D image. Is it right?

Best,

Hao Yu

[Andreas Morel-Forster]

Hi Hao Yu,

Welcome to the scalismo-faces community. I hope we can help you getting started.

to 1. :
For this you would need to establish the model-to-image correspondence (you need to know for each point from the model where it is in the image). Given also that you estimated the light, you can then look up for each point in the image which color you should set as texture/albedo on the model. The 3DMM way of doing that is to adapt the model to the image following a analysis-by-synthesis strategy. A good startingpoint for how to adapt the model to an image is section V. B. "Inverse Rendering" from the paper Morphable Face Models - An Open Framework for which you can finde code online here https://github.com/unibas-gravis/basel-face-pipeline, or the tutorial about probabilistic fitting from our PMM website.

to 2. :

UV unwrapping referes usually that you calculate a 2d embedding of your 3d (face) surface. E.g. for a triangular mesh in 3d it would be the mapping for each triangle in 3d to a triangular location in a 2d image, a texture. Depending on the task, the triangles can be arranged in the texture differently or even be mapped to multiple textures. Further, even that a 3DMM for faces can represent many different individual faces, you only need one uv embedding, as all faces share the same topology. For the BFM 2019 for example there is an 2d embedding provided that you can use with the scalismo-faces software.

Best, Andreas

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[Hao Yu]

Thanks a lot

在 2020年6月30日星期二 UTC+8下午11:20:54，Andreas Morel-Forster写道：

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