Data

This dataset has been created to meet the needs of the research community of Arizona State University. Aspect can be thought of as the slope direction. It identifies the down-slope direction of the maximum rate of change in value (elevation) from each DEM cell to its neighbor cells. The values of the output grid are the compass direction of the aspect. The data is derived from the 30 meter Digital Elevation Model created for Central Arizona - Phoenix LTER (dem30_utm).

Grid generation

The aspect grid was generated using the previsouly created 30 meter DEM (dem30_utm) in ArcInfo's grid function. Values in the grid were converted from floating point to integer format and value attribute table (.vat) was built. Although the original values are truncated, the accuray is not significantly affected. Aspect identifies the down-slope direction of the maximum rate of change in elevation from each cell to its neighbors. The values of the resulting grid are the compass direction of the aspect expressed in positive degrees from 0 to 360 and measured clockwise from the north. Cells in the input grid of zero slope (flat) are assigned an value of -1.