My country is extended to 4 zones so for calculating area I must set data frame properties in ArcMap (projected coordinate system). I have one shapefile with many polygons (about 300 polygons). I add new field named area and then use calculate geometry to this column to find area in (sq km) with just one specific UTM zone. It is difficult to set every polygons zone to find area. Is there any way? I create KMZ from shapefile with some polygons and opened it in Google Earth Pro but there is not any polygon properties option for them.
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Pick a country wide projection– Ian TurtonCommented May 27, 2023 at 17:47
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2If your main goal is to compute the area of polygons, pick an equal area projection (eg, Albers, Lambert) appropriate to your country, then calculate the polygon areas and store those in your shapefile.– LlavesCommented May 27, 2023 at 17:51
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If you can't change your data's projection, add each zone to your favorites (CRS) which makes it pretty easy to change zones, especially if you don't have to calculate areas often. If you don't need precise areas (or locations) you could use one of the central zones. You might compare those results with those where each polygon is calculated within its zone and see if you can live with the differences.– JohnCommented May 27, 2023 at 22:12
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1 Answer
If you have access to ArcGIS Pro 2.9 or later, you can use the Calculate Geometry Attributes tool. There's an option to calculate a geodesic-based area which is the area as if it's calculated on the ellipsoid surface so equal area. As a comparison, you can also set the coordinate system in which the values will be calculated, use an equal area projection (Albers or Lambert azimuthal equal area for instance), and the regular area option.
Or, as Llaves suggested, use the Project tool to create a new copy of the data in an equal area projection and then calculate the areas.
