Phong reflection model parameters
Q: Can anyone call me the Phong reflection model parameters for a face image taken for a webcam?
Details:
I am doing 3D reconstruction of 2D images using the 3D Morphable Model as in this article by Vetter and Blanz, 2003 .
There is a cost function that needs to be optimized using the Newton method. I need to give initialization values for Newton's method.
The equation below represents the fog reflection model of an image. Ambient, diffuse, and special components are displayed.
Phong parameters: Ks, Kd, Ka, α, Lm, V
I am evaluating the above parameters using Newton's method. The image has a human face and the camera is a webcam.
I gave the following values: Ks = Kd = Ka = 0.6 α = 5 Lm = [0 1 1] V = [0 0 1]
Can anyone comment on the above values and what might be a good initialization value for parameters
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My boss had a Siggraph document a few years ago that suggests an online tool that extracts a specific BRDF barcode for a Blinn-Phong model, based on gender, skin type, etc. The tool is available at: http://gvi.seas.harvard.edu/ext/facescanning/index.html
Alternatively you can check the Matusik BRDF database fittings at: http://people.csail.mit.edu/addy/research/ngan05_brdf_supplemental_doc.pdf and pick one BRDF that "looks" like leather (they didn't measure leather, since we used balls).
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