how to use illuminance map in skyscraper?

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hi guys, I used the 10 x 10 grid illuminance map for the three-story building, but in the illuminance map output has 100 grids should be 300 grid because three-story building and z-axis on each floor have the same height. So where can I set the height of the illuminance map to have 300 grid output?Or whether the illuminance map can be used only one level? oiya once again, I used an illuminace map for a three-story building where the surface is facing north and south. But when the building is rotated using a sketch up orientation east and west have the same coordinate every time. What should i do? thankyou very much