[Therion] mixing local and global coordinate systems

[Bruce]

Hi Jonny

No real answer, but you can equate two fixed stations, but you will need to specify error values for one or both of them.  I have done it before with coordinates in the same cs.  It should work for differing cs (I have done this in different circumstances), but of course not for an arbitrary coordinate system.  There are some interesting hacks needed in some circumstances, see http://article.gmane.org/gmane.comp.gis.therion/2909/match=loop+fix

Stacho indicated he would look at correcting some of the issues raised, perhaps why the next update is taking so long :-)

 

>From the therion book…

 

fix <station> [<x> <y> <z> [<std x> <std y> <std z>]] ◃ fix station coordinates (with specified errors—only the units transformation, not calibration, is applied to them).

 

And on transforming the plt coordinates, the calibrate option of the import command on page 33 of The Therion Book seems to suggest a way forward.  I have never used ‘import’ so cannot speak from experience.

 

Bruce

 

  _____  

From: therion-bounces at speleo.sk [mailto:therion-bounces at speleo.sk] On Behalf Of Jonny Prouty
Sent: Saturday, 4 August 2012 6:21 a.m.
To: List for Therion users
Subject: [Therion] mixing local and global coordinate systems

 

Hello all,

 

I have a compass PLT file that I would like to import into an existing therion project that I have. The therion project has numerous fixed stations, all in the same UTM zone. Unfortunately, if I try to equate a station in the PLT file with the equivalent station in my project, I can't proceed as I can't mix local (in the PLT file) and global (in my project) coordinate systems. If I comment out all of the "cs" commands in my therion project as a test, I can't proceed because therion won't allow two fixed stations to be equated with one another. Removing the "cs" commands isn't really a viable option anyways since I need the stations to have real-world coordinates so that I can load the maps into QGIS and GRASS.

 

My question then is is it possible to override the coordinates of an imported PLT file, transforming them into the coordinate system of my project? Thanks very much in advance!

 

Best regards,

 

Jonny

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