I have an autocad map that need to be imported in 3d max. so what I did is to export this map from autocad as a bitmap image. then import this map in 3d max ,the problem that its size is in pixels and Iíll be using Meters and Cm as measuring units. how can I have the same measures I had on Autocad.
Well, you didn't really define what capacity you wanted to use your map in 3D Studio. You'd only save it as a BMP (or any other image format) if you were going to use it as a backdrop or a material applied to an object inside 3D Studio. As I suspect that's not the result you were after, you probably want to simply import your .dwg file from within 3D Studio (File>Import>dwg) and it will have all of the same units it did in Autocad.
Hope that helps.