One of the more time-consuming parts of any modeling study can be preparing terrain elevation data. If your receptor network only extends over one or two quads, you may prefer to purchase these quads directly from USGS. But, if your network covers a large area, BEE-Line Software offers an affordable and convenient alternative. Our Digitized Terrain Data, or DTD, makes preparing terrain elevation data easy. DTD allows importing of elevations directly into your receptor, source, and GEP building data. If your data range crosses a UTM Zone, no problem, we extend the base zone into the other zone. We even adjust for mixed NAD27 and NAD83 data.