Working with Larry Fish's Compass

Survex can read Compass survey data - it supports survey data files and project files (.DAT and .MAK files), closed data files (.CLP), and processed survey data (.PLT and .PLF files). Survex 1.4.6 made significant improvements to this support so we recommend using this version or newer if you're working with Compass data.

Compass .DAT support

A Compass .DAT file contains raw survey data. You can process a .DAT file with cavern or aven as if it were a .svx file.

You can even use *include compassfile.dat in a .svx file and it'll work, which allows combining separate cave survey projects maintained in Survex and Compass.

One point to note when doing so (this tripped us up!) is that station names in DAT files are case sensitive and so Survex reads DAT files with the equivalent of *case preserve. The default in SVX files is *case lower. So this won't work

*fix CE1 0 0 0
*include datfilewhichusesCE1.dat
because the CE1 in the *fix is actually interpreted as ce1. The solution is to turn on preserving of case while you fix the point like so:
*begin
*case preserve
*fix CE1 0 0 0
*end
*include datfilewhichusesCE1.dat
If you want to be able to refer to the fixed point from Survex data too then you can add in a *equate to achieve that:
*begin
*case preserve
*fix CE1 0 0 0
*equate CE1 ce1
*end
*include datfilewhichusesCE1.dat
*include svxfilewhichusesce1.svx
Or if you're just wanting to link a Compass survey to a Survex one, you can use a *equate with *case preserve on:
*begin
*case preserve
*equate CE1 ce1
*end
*include datfilewhichusesCE1.dat
*include svxfilewhichusesce1.svx

Survex understands most DAT file features. Known current limitations and assumptions:

Compass .MAK support

A Compass .MAK file defines a survey project to process, and specifies one or more .DAT files to process, along with coordinate systems and fixed points. You can process a .MAK file with cavern or aven as if it were a .svx file.

Survex understands most MAK file features. Known current limitations and assumptions:

Compass .CLP support

A Compass .CLP file contains raw survey data after adjusting for loop closure. The actual format is otherwise identical to a Compass .DAT file, and Survex 1.4.6 and later support processing a .CLP file with cavern or aven as if it were a .svx file (the extra support is to recognise the .CLP extension, and to not apply the instrument corrections a second time).

You can even use *include compassfile.clp in a .svx file and it'll work, which allows combining separate cave survey projects maintained in Survex and Compass.

Usually it is preferable to process the survey data without loop closure adjustments (i.e. .DAT) so that when new data is added errors get distributed appropriately across old and new data, but it might be useful to use the .CLP file if you want to keep existing stations at the same adjusted positions, for example to be able to draw extensions on an existing drawn-up survey which was processed with Compass.

Another possible reason to use the data from a .CLP file is if that's all you have because the original .DAT file has been lost.

Compass .PLF/.PLT support

A Compass .PLT file contains processed survey data. The extension .PLF is also used for "special feature files" which have essentially the same format. You can load these files with aven as if they were .3d files, and similarly for other Survex tools which expect a .3d file such as survexport, extend, diffpos, 3dtopos and dump3d. (This support is actually provided by Survex's img library, so other programs which use this library should also be able to read Compass .PLT files without much extra work.)

Survex understands most PLT file features. Known current limitations and assumptions: