Matching your low to your high is dependent on how many triangles you are allotted for the asset. If you can get away with fewer triangles that is ok as the normal map of a fairly complex area like your grating and pipes will translate onto a plane ok. With that said, your low should match your high as close as possible so that when you set your cage up it can bake the best.
I think trying to get the normal map to fake the grate and the pipes is going to only end in disaster, none of it is going to parallax and it will only look good from the angle it was rendered at. A normal map just can't fake that kind of layered detail. Even a parallax map would have trouble with something like that... Maybe if the pipes where closer to the grate and the gaps where closed off with more pipes or wires so it was more like some minor surface bumps instead of a hallow chamber under the grate, it might work better...
The best way forward for that area is probably going to be do the grate on alpha, and toss in some low poly pipes. I also think the clips on the low poly are unnecessary, that's detail that is shallow enough that it could be handled by the normal map.
Last edited by Mark Dygert; 07-26-2011 at 09:50 AM..
Nah, that'll look stupid if you're not looking at it at a complete perpendicular plane. you need that depth and those cylinders. They can be 8-sided and you can delete the 2 lower faces that you don't get to see. But you can ditch those 'hinges' that are holding the grate in place.
, triangle, 409 Posts, Join Date Nov 2007, Location Montreal, Canada
Place the low poly elements and their corresponding high poly elements next to each other, but away from other parts of the mesh. IE, the grate from the high and the plane from the low poly should be moved up a bit and away from the 'base'. The two cylinders can be moved out of the groove. You want the exploded elements to NOT be close each other so they don't cast ambient shadows on each other. You will bake an unexploded version for that.
Leave the hinges and the plates on the right hand side as floaters for the 'base'.
Place a keyframe on frame one of the timeline. Move to frame 2, turn AutoKey on, move your elements of the high and low. Turn off AutoKey. Now when you move the timeline to frame 1 you will have a nonexploded mesh you can send off for an AO bake. Move to frame 2 and you have an exploded mesh you can send for its own Normal Map / AO Bake. Profit.