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The resolution of gridded digital terrain data is a measure of the level of detail available in the dataset. Specifically, the resolution of a terrain model is given as the size on the ground of each grid cell. Assuming the source for the elevation grid was detailed enough, smaller grid cells capture greater detail, and are referred to as higher resolution datasets. |
In addition, higher resolution also means either:
- smaller area covered (for a given number of grid cells), OR
- larger data volume (for a given area of coverage)
Our Elevation pages provide an easy way to visually compare the changes in detail and area covered for different resolutions.
Note, however, that the source data for the elevation grid must have adequate detail; simply making smaller elevation grid cells doesn't increase the detail if the source data are too general. For grids derived from stereo imagery, the resolution is limited by the pixel size of the imagery, but most often is produced at twice the image pixel size to avoid excessive "noise". For grids derived from contour maps, the most appropriate grid resolution varies depending on map scale, contour interval, and topographic relief.
Cell size is measured either in linear units like meters or feet, or in geographic units like degrees, minutes, or seconds. Data provided in geographic units, like SRTM, do not have a fixed grid size in meters because a fixed unit of longitude decreases in its corresponding linear measurement as one goes from the equator towards the poles. Often, such data will be resampled into a fixed linear grid with a cell size that's near the average size of the geographic cells.