Originally Posted by SDK Documentation
Performance and Budgets
Polygons counts for some of the Half-Life 2 characters:
Soldiers: 4682
Police: 3852
Resistance: 4976
Zombie: 4290
Helicopter: 6415
Strider: 6444
Alyx: 8323
There are no fixed rules in determining how many polygons you use in your model, or how much texture resolution you'll use in your materials. There are upper limits of engine capability, (10,000 polygons/model, 17,433 vertices and 2048 texture size) but these aren't usually going to be what you're shooting for. You'll need to consider how many of the character, vehicle, or prop you're making will be on screen. If you'd like dozens of them on screen at any given time, you'll have a different budget than if you'd only like to see one of them ever on screen at a time. With humanoid characters, especially for multiplayer use, you shouldn't need to go over 4000 polygons to get a character that has enough detail to accurately describe the form, bend properly at the joints, and have enough edges to light properly. Of course you can have more than that, but with normal mapping, and high res textures, you shouldn't really need to.
One good thing about working in XSI is that you can keep your model as quads and have clearly organized edges (edge loops) that define the shape, with this sort of a model, it is easy to add and dissolve edges, especially since the UV coordinates are preserved and you can easily re-envelope your mesh with saved vertex weights. Discrete levels of detail are supported in the Source engine and can drastically improve scene rendering speed.
