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mach0 / qchainage

Chainage Plugin for QGIS
GNU General Public License v3.0
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Geodetic Calculation #22

Open rmaf27 opened 4 years ago

rmaf27 commented 4 years ago

Is it possible to add a way to calculate in geodetic instead of projected? Thank's

HerrRuin commented 4 years ago

Hello Werner, that is exact what I mean. :) The tool calculate the projected length. For long lines, it makes a difference in geodetic view. It is the real length for the polyline, but it misses the utm scale factor.

You can try. Draw a line of 40 km length. Try with your tool and with the function qgis field calculation $length. Your length is shorter, because it misses the round earth. http://www.drillingformulas.com/scale-factor-in-utm-mapping-system-and-its-application-in-directional-drilling/

Hope you can find a way for that problem. Stephan

mach0 commented 4 years ago

I'll have a look at this, but currently busy with building my house. If anyone is willing to prepare a pull request I am more than open to release a new version.

etaunknown commented 4 years ago

Definitely would be an excellent addition :)

For other GIS novices like myself, the plugin uses the cartesian rather than the ellipsoidal distances.