Help with Compass dat files read (and processed) by Survex

[Josep Guarro]

Hi Olly, thank you very much for your information on both emails

>It sounds like Ariane's .DAT export is incorrect for metric data.

Yes, that is the issue, also the entrance coordinates are lost on Ariane's .DAT export, I will write to the Ariane's author to let him know these issues.

In the meantime I sorted it out with a spreadsheet, converting the length data on the .DAT export to feet and then copy/paste to the .DAT file, so now I have all the lengths on the .DAT export in feet, and then when is processed by Survex it is shown the true lenght of the survey in meters, and matches exactly with original Ariane's data.

Again, thank you
Josep

On Sun, Oct 12, 2025, at 9:22 PM, Olly Betts wrote:
> On Sun, Oct 12, 2025 at 07:42:28PM +0200, Josep Guarro wrote:
>> I see on the DAT file that the shot lengths values from station to
>> station are the same ones that in Ariane, for instance shot form
>> station 0 to 1 in Ariane (metric) is 15.86m, then on the compass
>> exported DAT file I see also that from station 0 to 1 the length is
>> 15.86 but I do not know why survex is assuming those lenghts are in
>> feet?
>
> It sounds like Ariane's .DAT export is incorrect for metric data.
> Here's the documentation for the DAT format:
>
> https://fountainware.com/compass/HTML_Help/Compass_Editor/surveyfileformat.htm
>
> Against length, left, up, down, right this says (my emphasis):
>
> | It specifies [length/distance] in *decimal feet*
>
> So the DAT file should not say 15.86 if the length is 15.86m - instead
> it should say 52.034 (or 52.03 or however many decimal places you think
> appropriate).
>
>> I'm not used to Compass, is there any way to write down in the compass
>> DAT file that the lenghts are in meters rather than feet?
>
> There are two fields which say what the **ORIGINAL** length/distance
> measurements are in:
>
> | II.	Length Units: D = Decimal Feet, I = Feet and Inches M = Meters
> | III.	Passage Units: Same as length
>
> However the measurements themselves should always be converted to
> decimal feet (so the "Length Units" field lets you display the
> measurement in its original units, though may be rounding issues for
> some values - storing an extra decimal place as I showed above should
> reduce that problem significantly).
>
> (My guess is that originally Compass only supported feet, and when
> metric support was added Larry chose to leave the distances in metric
> so that existing readers of the file could continue to work with new
> files.)
>
> Angles are handled similarly - they're always stored in decimal degrees
> with fields to say what the original measurements were in.
>
> Cheers,
>     Olly

-- 
-----------------------------------
Josep Guarro