Three-Meter Digital Elevation Model of Iowa [Iowa]
This data set represents a digital elevation model (DEM) of the land surface of Iowa, in the UTM projection, Zone 15, NAD83 horizontal datum, with elevation in centimeters NAVD 88 vertical datum. The DEM has a horizontal resolution of 3 meters and was aggregated from one meter resolution elevation data from the state of Iowa's LiDAR program. The aggregation process uses a 3x3 pixel moving average window, which helps to smooth out noise in the one meter data, but also softens sharp edges of landscape features such as ditches and ridges, which may be undesirable for some purposes. The DEM was then Integerizied to shrink the size of the file, so final units are in centimeters. Water features sometimes have a triangular appearance due to lack of lidar returns over water and should be ignored.