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wvayens75 post(s)
#07-Jan-22 23:18

Given that I have 2 layers in lat/long, using GeomDistance I'm assuming the result is in degrees. How do I best convert this to feet/miles?

Thx.

oeaulong

378 post(s)
#08-Jan-22 00:58

Easiest thing to do is to display them in a projected map, then use the Tracker tool to measure their geographic distance as adjusted by the projection units. For SQL analysis, Check out Dimitri's discussion here: https://georeference.org/forum/t153908#153910

about the GeomLengthGeo() function.

lionel

873 post(s)
#17-Jan-22 00:41

https://georeference.org/forum/t153908#153910

=> New to MFD9...measurement problems (georeference.org)

GeomLengthGeo()

=> Geom SQL Functions (manifold.net)

GeomLengthGeo(<geom>, <major>, <eccentricity>, <tolerance>): <value>

Given a geom that contains an area or a line object, and values for major axis, eccentricity, and tolerance, returns the geodetic length (computed on the surface of the ellipsoid) of that object, computed using Vincenty's formulae A tolerance of zero means automatic tolerance.

The length of an area object is the length of its boundary, that is, the perimeter of the area. The length reported for a branched object is the sum of the lengths of the branches.

The geom value must be an area or line in Latitude / Longitude, with X (longitude) and Y (latitude) expressed in degrees. The returned value is in units of the major axis.

Looking at the Custom tab of the Base Coordinate System dialog for the WGS84 base used for Latitude / Longitude projection, we can see the major axis is 6378137.01 and the eccentricity is 0.08181919084262149

Given a Mexico drawing of provinces as areas in Latitude / Longitude coordinate system, we can write:

SELECT GeomLengthGeo([Geom], 6378137.01, 0.08181919084262149, 0) AS [Geodetic Length] FROM [Mexico];


union, doc , APIand most important deepl & keyboard shortcut

wvayens75 post(s)
#17-Jan-22 18:01

Where is the Tracker tool I've seen mentioned a few times. (I'm familiar with it in M8, haven't seen it in M9.) There are a couple of references in the manual, but for the life of me, I can't locate it!

Sloots

554 post(s)
online
#17-Jan-22 18:24

See this topic in the manual.


http://www.mppng.nl/manifold/pointlabeler

wvayens75 post(s)
#17-Jan-22 18:46

Thanks!

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