But you use fromdepth and todepth as quantity. Shouldn’t it be calibrate
fromdepth todepth 4 -1 ?
Martin S.
> 30. 9. 2021 v 12:59, Torsten Schnitter <torsten.schnit...@netcologne.de>:
>
> Due to the different waterlevel there is a difference of 4.0m in depth
> readings.
> To correct this I used "calibrate depth 4 -1" within the resurvey data.
From Therionbook:
calibrate <quantity list> <zero error> [<scale>] . set the instrument
calibration.
The measured value is calculated using the following formula: measured value =
(read value - zero error) x scale. The supported quantities are the same as sd.
From Survex manual:
4.5.3. CALIBRATE
Syntax
*calibrate <quantity list> <zero error> [<scale>] *calibrate <quantity list>
<zero error> <units> [<scale>] *calibrate default
Example
*calibrate tape +0.3
Description
*calibrate is used to specify instrument calibrations, via a zero error and a
scale factor. By default, the zero error is 0.0 and the scale factor 1.0 for
all quantities.
<quantity> is one of TAPE|COMPASS|CLINO|COUNTER|DEPTH|DECLINATION|X|Y|Z
Several quantities can be given in <quantity list> - the specified calibration
will be applied to each of them.
You need to be careful about the sign of the ZeroError. Survex follows the
convention used with scientific instruments - the ZeroError is what the
instrument reads when measuring a reading which should be zero. So for example,
if your tape measure has the end missing, and you are using the 30cm mark to
take all measurements from, then a zero distance would be measured as 30cm and
you would correct this with:
*CALIBRATE tape +0.3
If you tape was too long, starting at -20cm (it does happen!) then you can
correct it with:
*CALIBRATE tape -0.2
Note: ZeroError is irrelevant for Topofil counters and depth gauges since pairs
of readings are subtracted.
In the first form in the synopsis above, the zero error is measured by the
instrument itself (e.g. reading off the number where a truncated tape now ends)
and any scale factor specified applies to it, like so:
Value = ( Reading - ZeroError ) * Scale (Scale defaults to 1.0)
In the second form above (supported since Survex 1.2.21), the zero error has
been measured externally (e.g. measuring how much too long your tape is with a
ruler) - the units of the zero error are explicitly specified and any scale
factor isn’t applied to it:
Value = ( Reading * Scale ) - ZeroError (Scale defaults to 1.0)
If the scale factor is 1.0, then the two forms are equivalent, though they
still allow you to differentiate between how the zero error has been determined.
With older Survex versions, you would specify the magnetic declination
(difference between True North and Magnetic North) by using *calibrate
declination to set an explicit value (with no scale factor allowed). Since
Survex 1.2.22, it’s recommended to instead use the new *declination command
instead - see the documentation of that command for more details. _______________________________________________
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