Cartography

Choose your North Arrow wisely; it implies Magentic or True North.

Submitted by emarsh on Wed, 2009-02-25 11:35
in

I always chose my north arrow based on style. However, my advisor reminded me to be more careful, as explained here: http://www.cavesurvey.com/north_arrows.htm

Basically, a north arrow with two sides indicates true north, while an arrow with one side indicates magnetic north. Choose wisely.

On a related topic, you can calculate the magnetic declination of your location here: http://www.ngdc.noaa.gov/geomag/

 

Finding the right transformation when re-projecting data in ArcGIS 9.2

Submitted by emarsh on Wed, 2008-01-16 22:45
in

So you're using the Project Tool to re-projecting a map into a new projection.

Before you can start the process, you have to choose from the many transformations. The attached file (World Projections.xls) lists where in the world each projection transformation should be used.

For example, if your map is in PSAD56, and you want to project it to WGS84, the Project Tool will ask you which transformation you want. Checking the lists for Bolivia, I find: PSAD_1956_To_WGS_1984_2

Finding the right transformation when re-projecting data in ArcGIS 9.2

Submitted by emarsh on Wed, 2008-01-16 22:43
in

So you're using the Project Tool to re-projecting a map into a new projection.

Before you can start the process, you have to choose from the many transformations. The attached file (World Projections.xls) lists where in the world each projection transformation should be used.

For example, if your map is in PSAD56, and you want to project it to WGS84, the Project Tool will ask you which transformation you want. Checking the lists for Bolivia, I find: PSAD_1956_To_WGS_1984_2

 

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