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What is the reprojection in FME that is closest to the Geodesic Area calculations used in ArcGIS?


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In ArcGIS, we have been using the geodesic area calculations to calculate polygon areas in square kilometers from a geographic coordinate system such as WGS84. See http://dmahr.com/2015/07/geodesic-areas-arcmap-field-calculator/. I don't seem to find a similar reprojection in FME. is there an one that is closet?

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Best answer by redgeographics 4 March 2021, 09:05

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You have two options:

  • Reproject to an Equal Area coordinate system that's relevant for your area-of-interest and then the regular AreaCalculator
  • Use the GeographicAreaCalculator custom transformer, it will reproject to a generic Equal Area system centered on your feature and then calculate the area. Because of that there might be small variations between this option and the first one.
Badge +4

You have two options:

  • Reproject to an Equal Area coordinate system that's relevant for your area-of-interest and then the regular AreaCalculator
  • Use the GeographicAreaCalculator custom transformer, it will reproject to a generic Equal Area system centered on your feature and then calculate the area. Because of that there might be small variations between this option and the first one.

@Hans van der Maarel​ , we are doing area calculations for global datasets. I tried a couple of Equal Area projections, do not seem to work well on global datasets as expected. Will try this GeographicAreaCalculator and see how it compares with the arcgis geodesic area calculations. The latter has been accepted by our users.

Badge +4

You have two options:

  • Reproject to an Equal Area coordinate system that's relevant for your area-of-interest and then the regular AreaCalculator
  • Use the GeographicAreaCalculator custom transformer, it will reproject to a generic Equal Area system centered on your feature and then calculate the area. Because of that there might be small variations between this option and the first one.

@Hans van der Maarel​ Just let you know the GeographicAreaCalculator custom transformer gives exactly the same results as using this in ArcGIS -  http://dmahr.com/2015/07/geodesic-areas-arcmap-field-calculator/

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