Q 1."Maya does not support mirrored normal map."

wht does it mean?

Originally Posted by

Mirrored normal maps?
U mean mirrored uv's with normal maps?
Just apply a checker map with numbers or letters on your mirrored meshes to see why. if u cannot read the letters the letters are inverted, so u need to flip the mirrored uv's.
If the uv's are flipped the checker map is inverted meaning the concave details of your normal map turn into convex information.

Originally Posted by

You can also toggle a shaded view of your uv's, any inverted uv's will show up as red as opposed to the normal colour of blue

Originally Posted by

Q 2:Before baking normal map frm high res object to low res object why the hard edges r kept a small distance?

I know, it is to because avoid "the black lines"(i dunno why they show up.Can anyone explain)?But then it creats a problem for seamless texuring!

Originally Posted by

Hardedges black lines are caused by missed rays, the angle is too steep or narrow for the rays to hit.
A missed ray during normal generation will result in a black line.
To avoid black lines apply minimal smoothing groups or apply a chamfer.
the downside is when u're low poly mesh is too low poly and has minimal smoothing groups applied, u will see some nasty black gradient on your mesh, this is pretty shit cuz u will bake that gradient right on your normal map.

To avoid all those problems , try baking with a LP mesh that has a proxy /sub-d modifier applied to it.
It doesn't have to be like that, when u're low poly mesh has nuff interpolation, meaning the enough edges to wrap it's edges around the highpoly model u can get away without a sub-d proxy.

Originally Posted by

It is possible to stack uv's of a similar shape. Say you have a screw that is used several times, the uv's can sit on top of each other and you will have no problems with your normal map.

Originally Posted by

Another way to reduce the black lines is to seperate the uv's where you have a hard edge, but this is not always desireable.

Originally Posted by

If you need to Mirror the normal map on a symmetrical model you can lay out the uv's as you normaly would, then when you want to bake your map either delete one half of the model or seperate the uv's down the center and move one half out of the way. Then you can revert the uv's to how they were before

Originally Posted by