I have created a poly model hires at 33192 tris in maya.
my low res that i created the high res model from was 4354 tris,
I’m creating a game for android ios.
from what i have read i have to lower my tri count to 1500, which I have done by deleting edges verts.
I have created a uv map for the high res a texture map for the 33192 high res model.
I now want to apply a normal map the texture map to the low res from the high res but the topology doesn’t match i have not unfolded the uvs for the 1500 low res model.
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is there a better way of lowering poly counts in unity or maya not losing topology?
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should i just redo the texture map for the low poly model or should i unfold the u.v’s for the low res try match the high res uv map?
ive never had to back track when modeling from a high to low res so this is all new to me, if anybody can giv me some advice it would be greatly appreciated,
ta very much
bang tidy
Unwrap your low however you want. Then use xNormal to bake everything across.
You primarily need to have the lower one uv mapped, because your projecting the details form the high model, to the lower res one. The uv mapping is where those details endup being created on.
so it does not matter if the low res model that I have now unwrapped, does not match the uv map of the high res model, or have the same topology?
as long as i use xNormal to bake out the texture map?
Correct. xNormal will generate diffuse/normal/ambient occlusion/other maps when given a high poly and a low poly model. You’ll want to play with the settings to get good results though. And some areas can be problematic, especially between fingers and sometimes between the legs.
Hi niosop, thank you very much for the help, i have downloaded xNormal, i understand that you can generate diffuse/normal maps etc,
In maya due to me creating a uv map 1st from the high res 33192 tris model then creating a uv map from the low res 1500 tri model, the topology uv mapping do not match, so when i bake the two high low the maps seem to be overlapping, am i not doing something right in xNormal or do i have to go back to maya rework the uv map for the low 1500 tri to match the high?
How it should work is your projecting the details of the low res model, to the high one. If your getting some strangeness you need to adjust your settings. The reason your low res model doesn’t need to have the same UV Map is because the baking process just copies the detail information on to the low res model. It should do so based on its uv’s, not the high res ones.
Something to keep in mind is by deleting edges you don’t actually make good topology, and you should triangulate the model before any export, as unity will do this and it can make the uv’s a bit funky, as some of those edges will come back 
you do not need to make a UV to the high poly at all; just for the low poly to project the high poly details into the low poly
You might if you were planning to pass on the high res painting tho if you planned to just paint the low res uv’s then no.