Use the "Add Path" tool to draw a dense grid or zig-zag pattern over your site. The more points you click, the more accurate your final topography will be.
Right-click your path in the "Places" panel and select Save Place As . Save it as a KML file (not KMZ) to ensure compatibility with most converters. 2. Converting Points to Contours
Download SRTM or ASTER DEM (Digital Elevation Model) from: