How works lightmassimportant Volume?

Is this tiling normal?(look picture!)

Hi michelle0309,

The lightmass importance volumes increases the relevance of any lighting that occurs inside of its bounds. As such, it places a greater importance on these areas when rendering. You will want to make the lightmass importance volume encompass the playable area of your map. If it is an archviz, I would go ahead and encompass the whole map. The black spots look like a UV map issue, I would look at your UV’s and make sure you have a second UV channel and that you do not have overlapping UVs on your models. Especially in regards to the cylinders in the front of the picture, it looks like the sides are definitely overlapping. Make sure you have created your seams in such a way that that lays out flat on the UV map.

The sunlight is not improved because it is not in the light Mass Volume? How can I set the points in the grid height and width.In time is no light in the grid, after which Lightmass directed otherwise in the distribution of points?

Any objects in the lightmass volume that are hit by light from your lightsource (the sun) will have improved rendering quality.