Glossary for Geospatial Science

nominal image map:  A preliminary map form that approximates an image map and that can usually be prepared using fully automated procedures.  For example, TNTmips can automatically extract a 7.5' nominal image map from Landsat or SPOT satellite images using the positional and angular properties provided with the images.  However, to convert it to an accurate image map, the user must introduce ground control points.

A topographic map that has been scanned (but not yet calibrated) is another example of a nominal image map.  Similarly, using TNTmips to mosaic airslides or airvideo images that cover the area of a 7.5' map provides a nominal image map. (By contrast, rectifying and assembling these source images yields an image map, since that process used ground control points in some map coordinates.) (See also: image map.)