A GEOTIFF is a special kind of TIFF file that contains information about the map projection and registration. 

Data Manipulation

The Geotiff format has a huge number of options, and some combinations might present problems for MICRODEM.  If this happens, MICRODEM will call GDAL to convert to a more generic Geotiff.  The most common problems are tiled images, compressed images, and unsual color representations.  The original file will have "original_' added to the start of the file name.  The GDAL version will have the original name.  You can delete it if the converted file works.  If the converted file does not work, you will have to figure out the problem.  MICRODEM cannot do anything more with the file until the source code is changed.  If you have a sting of files "original_original_......" they will all be the same.

The program can also handle TIFF files with a TFW world file containing registration information, although in that case you will probably have to set the UTM zone when you load the file.

The program will ignore all images in a geotiff after the first, and will warm you of this fact. It uses Tiff Tag 254 to identify a second image.

 You must correctly identify the Geotiff as either an image or a DEM.  The image can be opened as a DEM, but will not have all the imagery display options.

Once loaded, the GEOTIFF behaves like any other image or DEM.

Geotiff imagery and DEMs

Imagery stored in multiple files (one band per file).

The program will save maps in GEOTIFF format. Once saved in this format you have a dumb image, and if it was a DEM, it no longer has the elevation information.  You can save the DEM as a Geotiff.

 MICRODEM does not use Geotiff as its default grid format because:

  1. Geotiffs load more slowly than the MICRODEM format.  Fixing this is on the to do list, but not the highest priority.
  2. MICRODEM stores the z units, which facilitates display and allowing appropriate options depending on the nature of the grid.  GeoTIFF does not.  As a workaround, MICRODEM uses a non-standard tag to store the z units.

GEOTIFF DEMs have the following characteristics and limitations:

Last revision 10/8/2021