GIS & GPS

Large and active forum discussing ArcGIS issues. Great place to search for answers to puzzling ArcGIS problems.

To convert DMS values to decimal degrees (e.g., 45:30:30 to 45.50833), multiply the DD:MM:SS value by 24, and format the cell as General. For example, =A1*24

Simple form from NOAA for calculating the most current magnetic declination for any location on the planet. For use with declinating compasses.

Wikipedia contains a fairly detailed description of the functioning of the GPS system.

Useful list of suggestions from the USFS about use of research grade vs recreational GPS units, getting reception under the forest canopy, projection transformations in Arcpad 7 and more

Useful tutorials introducing techniques in ArcGIS

Allows you to send very large files to people via email. Rather than using attachments the recipient just gets a link that they click on. This service is better than YouSendIt.

This unit conversions page is useful because it also supports areal and volumetric conversions.

On a related note, unit conversions are possible inside of Arcmap as follows. "When editing in ArcMap, you can do on-the-fly unit conversion if you specify the unit type when you type a distance (by right-clicking). When you enter a distance into a pop-up window, press F1 to get a list of the unit abbreviations you can use." (Arcmap help)