different looks of lightmap in Unity from Maya

Hi,

I baked a lightmap (color and light) in Maya and import the .mb file in Unity. I applied the baked lightmap (import as lightmap) as the texture for the Lightmapped diffuse shader in Unity. It looks very coarse, like a painting. How can I bake the color and light map and export it to unity so that it looks like photograph, or same as in Maya? Thanks very much!

Check that you’ve turned down the ambient light in the Unity render settings.

Yes I turned it down. I think I plugged the lightmap texture into wrong slot. I now plug it into lightmapping->maps and it works good now. However, it still shows weird bee hive pattern on these boxes, which should be pure grey. It should be a problem in Maya baking since the pattern is shown in the baked texture. I used fill texture seams 3. Do you know why? Thanks!