5 replies to this topic

[Hootan]

I have a shapefile and the geographic coordinate system of it is GCS_WGS 1984. When I open its attribute table, in the shape area column I see some numbers but I don't know what the units are, can anybody help me with their units??

[Hans van der Maarel]

I have a shapefile and the geographic coordinate system of it is GCS_WGS 1984. When I open its attribute table, in the shape area column I see some numbers but I don't know what the units are, can anybody help me with their units??

Logically speaking, they should be decimal degrees. I.e. always between -180 and 180 for the x, -90 and 90 for the y coordinate.

[Hootan]

I have a shapefile and the geographic coordinate system of it is GCS_WGS 1984. When I open its attribute table, in the shape area column I see some numbers but I don't know what the units are, can anybody help me with their units??

Logically speaking, they should be decimal degrees. I.e. always between -180 and 180 for the x, -90 and 90 for the y coordinate.

How can I convert those numbers to the meter unit? (For example one of the numbers under the shape area column is 0.0049)
Is there any way to change the coordinate system of all the shapefiles to the meter unit coordinate ?

[Hans van der Maarel]

Geographic coordinates are usually not given in meters. Do you want to reproject the data? If so, to which projection?

[DaveB]

Degrees doesn't really make sense for area units. The best thing to do is to reclaculate the area with whatever units you want to use there, probably miles or kilometers for large areas, or meters or feet or whatever you prefer for your use. If you are using ArcMap here's a topic from ArcGIS 10 Desktop Help about calculating area.

[Hans van der Maarel]

Degrees doesn't really make sense for area units. The best thing to do is to reclaculate the area with whatever units you want to use there, probably miles or kilometers for large areas, or meters or feet or whatever you prefer for your use. If you are using ArcMap here's a topic from ArcGIS 10 Desktop Help about calculating area.

Oh duh... I should have read a bit more carefully