topic Re: How to convert AngularUnits (Degrees) to LinearUnits (Meters?) in ArcGIS Pro SDK Questions

How to convert AngularUnits (Degrees) to LinearUnits (Meters?)

HoriaTudosie — Thu, 21 Jul 2016 00:00:43 GMT

Polyline.Lengths returns Degrees (as defined per SpatialReference.Unit,) but I would rougher display it in meters.

However AngularUnit does not have a ConvertToMeters methods...

(B.T.W the snippet "LinearUnit - Convert between centimeters and millimeters" is so pathetic...)

Re: How to convert AngularUnits (Degrees) to LinearUnits (Meters?)

JayantaPoddar — Thu, 21 Jul 2016 02:55:39 GMT

You could reproject the data to a Projected Coordinate System.

Project—Data Management toolbox | ArcGIS for Desktop

You could define a Projected coordinate system to new data frame, add the layer using appropriate transformation method. Then, add a new field (say "Len_mtr"; Datatype="Double"). Using Calculate Geometry, you could define the length in linear unit using the coordinate system of the data frame.

Re: How to convert AngularUnits (Degrees) to LinearUnits (Meters?)

ThomasEmge — Thu, 21 Jul 2016 23:25:10 GMT

I believe you are looking for this ArcGIS Pro 1.3 API Reference Guide

Re: How to convert AngularUnits (Degrees) to LinearUnits (Meters?)

HoriaTudosie — Fri, 22 Jul 2016 17:20:05 GMT

Not Exactly:

While measuring Geodesic lengths is nice, It does not interest me much since I measure roads length.

However the result I get is in Degrees, and I would want it in Meters, which others have given hints but not solutions (like in code...)

Re: How to convert AngularUnits (Degrees) to LinearUnits (Meters?)

ThomasEmge — Fri, 22 Jul 2016 18:11:14 GMT

The geodesic length is providing shortest path on the ellipsoid. Depending on the length of your geometry you will indeeed see a difference in the actual length value for computed planar length or geodesic length - in either case the GeodesicLength method will provide you the answer in meter in the case the original geometry is a geographic coordinate system.

It is not possible to just convert an angular unit value to a linear unit as there is a dependency on the location on the sphere/geoid/ellipsoid. To transform the information from a geographic coordinate system to a projected system (using linear units) you need to project the geometry. Here is a very nice description about the principles of map projections.

For code examples please take at look at this location.

- Thomas