is an amazing piece of software. All you need to generate a 3D representation of most anything is to take a bunch of pictures around it and 123D Catch will create a 3D model.
123D Catch prefers that the lighting is even and it requires that nothing moves. We took a series of photos around ourselves in order to resolve our faces. Angular spacing of 5 to 10 degrees is best. 20 or 30 pictures worked here. You'll have to experiment as things like hair and beards will affect the model.
Simply load the pictures into 123D Catch and generate the model. They are loaded into the cloud to do its work.
Once you have a model that looks like it is going to work (this might take a few tries), you'll want to generate a high res version of it and then export that as an .obj file. Don't worry about all the extra stuff, just make sure that the face looks ok.
Now that we have the 3D file we can work on modifying it in order to remove the extra parts and smooth out any bumps. We will use some other free software to accomplish this.