Modeling Faces (or other organic things)
I recently have been learning a lot about modeling and just learned a very good lesson about modeling faces.
Anything I produce for this community will be using free/open source products. I use blender exclusively, and excellent open source 3d development platform (http://www.blender.org). Since its free you will see a wondrous amount of learning material online.
Here are a few i recommend:
Blender Cookie - http://cgcookie.com/blender/
David Ward on YouTube - http://www.youtube.com/user/ward7299
When you are going for photo realism, it makes sense to have photo realistic pictures. This applies to not only faces, but also things such as grass, bricks, that sort of thing. Take a picture of whatever it is you want to model. When the anatomy of the human body is just a little off the human eye will pick up on it. So it’s important to get as much of the anatomy correct in the model as you can. I recommend taking your pictures yourself, or of a friend. Even most cell phone cameras will even work well for this.
When you are modeling a face it’s important to have correct topology on the model, to avoid any deformations when you want to animate it, or change facial features. Unfortunately when you do research for modeling for games, you will get something close to this:
This is something that would be appropriate if the character were to be moving around on the screen, and we don’t want it to take up a ton of recourses, so the polygon count is lowered by using triangles. When you want very detailed photorealistic models, triangles create issues when you want to subdivide them to create smooth organic shapes.
Typically, you want to have your face divided up into all quads with distinct rings around key areas. I have included this picture, showing key areas in color. (though is not very accurate in the anatomy department, this is only for demonstration)
In the above picture, there some circled vertices. These are called poles. They are vertices that are connected to more or less than 4 other vertices. They are required in order to change the flow of the topology over the face, but use them sparingly as they will not deform correctly when pushed or pulled very well.
In closing just remember to be thinking of the overall shape of your model as you are creating it, and pay attention to the flow of your topology, to prepare for the future. When learning to model it can be frustrating, but with surprisingly little practice you can be producing some wonderful images.