Facegen Customizer

Model fitting and projection mapping

With a good generic model and UV mapping, we can move on to combining the photographs into a single texture. First, we need to alter our generic model to match the photographs. Hong Suck Suh and Paul Fedor show the best practice for doing this in the traditional way: modeling by hand with the photographs as a reference and then morphing the photographs to fit a plane projection onto the model. I will show an alternative approach here, and highlight advances that can be achieved with some DirectX shader tools that I have developed for blending multiple photographs onto one model.

In the first step, I use FaceGen to generate a fitted head model using the front and two side photographs. I do this on the 2K version of the model from which I know all changes can be easily propagated to the 9K and 36K models. FaceGen is a parametric head modeler from Singular Inversions that we will take a close look at in the chapter on 'Parametric head modeling'.

There are several approaches to combining photographs onto a modeled head, but all of them share one common element—the projecting of the photographs onto the 3D head using one UV (projection) mapping per projection and rendering out (called unwrapping or baking) the projected photograph to the desired (unified) UV mapping. You repeat this with photographs from many angles and combine all the unwrapped photographs. There are a number of approaches to the core problem of accurately projecting, warping and combining the source photographs:

2. You can temporarily alter the model to fit each projected photograph (this does not alter the target UV mapping), render out the unwrapped photographs and combine them all in 2D and apply them to your original 3D head. This approach has the benefits of doing everything in the floating-point color space in your 3D software. An even bigger benefit is that there is a far richer set of tools for warping a 3D model than you can possibly get in any 2D software like Photoshop.

3. You can alter your 3D head model to fit all of your projected photographs, unwrap and combine your textures which you then apply to the refined 3D model. Your model now fits the photographs as precisely as possible and you get the best quality texture possible. This is the best overall approach, but it requires a very good fit of the projected photographs to the model.

Whichever method you use, you will have to color-match the individual unwrapped photographs. This has to be done by hand and in small pieces—even with consistent lighting there are color variations. The relative color and luminance will vary across each photograph as a function of the diffuse, sub-surface and specular properties of the skin.

1. You can leave the model as is and warp the photographs in Photoshop to fit the projected mapping. You can also do this in your 3D application where you'll get the benefits of floating-point color representations and a richer set of 2D warping tools than in Photoshop.

show solutions to both the color-matching and accurate projection problems which make the third approach both the easiest and highest quality. For this chapter, I developed a DirectX shader that was meant as a tool for displaying multiple projected maps concurrently on the one model. The shader development went so well that I was able to add an automatic tone-mapping function that does a perfect blend of all the projected photographs in real-time and at every pixel. As you'll see the results are astounding!

Facegen Models Download

O Step 1: Photo fit with FaceGen

FaceGen is a parametric head modeler Dased on principal component ana/ysis of a large database of human heads As such, it is free from any user (or programmer) bias and is mesh-independent I used the FaceGen Customizer to generate a version of our head model to import into FaceGen Generating a fit to a photograph is an easy process that takes lust 10 minutes or so The fined head is parameterized and can be applied to any topology head model Once fined, the head mesh is exported out to ob< format and brought into 3ds Max for the next step

Good Head Topology
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Responses

  • filibert
    How do u get the model u imported with facegen customizer in to facegen modeler ?
    7 years ago
  • Liisi Oksanen
    How to add facegen head mesh to a body?
    5 months ago

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