Re: [Therion] Wrong average calculation from compass/backcompass data

2018-05-27 Thread Footleg via Therion 
The correct way to average bearings is to the treat them as vectors, then
average the x and y components separately before converting the resulting
vector back to a bearing. It is likely this is what the trig functions
mentioned in this thread are doing.

Footleg
On Fri, 18 May 2018 at 12:57, Bruce Mutton via Therion 
wrote:

> I agree to some extent with both sentiments below, however the software
> should not abort just because of backsight discrepancies.
>
> What about adding one more line to the Therion and or Survex log file;
> either
>
> “There are no backsights in the centreline”, or
>
> “Maximum backsight discrepancy is xx [degrees|grads]”, as approprite
>
> That way the user can be fully informed and make their own decision about
> whether to investigate further if the information is not what they expect.
>
> Bruce
>
>
>
> 17. 5. 2018 v 9:25, Evaristo Quiroga via Therion :
>
>
>
> In this case is not a problem with my formula, is a serious magnetic
> anomaly (100 degrees difference)  and the program should to stop and to
> send a warning.
>
>
>
> Evaristo,
>
>
>
> Therion is a program to interprete your data, not to solve problems with
> your data.
>
>
>
> It is your responsibility what the data you import into Therion.
>
>
>
> Martin S.
> ___
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> Therion@speleo.sk
> https://mailman.speleo.sk/listinfo/therion
>
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[Therion] Wrong average calculation from compass/backcompass data

2018-05-18 Thread Bruce Mutton via Therion 
I agree to some extent with both sentiments below, however the software
should not abort just because of backsight discrepancies.

What about adding one more line to the Therion and or Survex log file;
either

"There are no backsights in the centreline", or

"Maximum backsight discrepancy is xx [degrees|grads]", as approprite

That way the user can be fully informed and make their own decision about
whether to investigate further if the information is not what they expect.

Bruce

 

17. 5. 2018 v 9:25, Evaristo Quiroga via Therion  >:

 

In this case is not a problem with my formula, is a serious magnetic anomaly
(100 degrees difference)  and the program should to stop and to send a
warning. 

 

Evaristo, 

 

Therion is a program to interprete your data, not to solve problems with
your data.

 

It is your responsibility what the data you import into Therion. 

 

Martin S.

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Re: [Therion] Wrong average calculation from compass/backcompass data

2018-05-17 Thread Olly Betts via Therion 
On Thu, May 17, 2018 at 09:25:23AM +0200, Evaristo Quiroga wrote:
> I attach the original file with the fore/back sight (SCAGUA.th) and a
> manually averaged  (SCAGUA_avg.th) to compare if Survex and Therion work
> well. The error loop is similar between the two files (2,9m) but I have to
> check if the station are positioned at the same coordinates.

I feel I should point out that Survex's handling of backsights isn't
coming in to play here at all - Therion flattens away the backsights
so they don't appear in what it asks Survex to process.

Out of interest I did a crude conversion of the two attached files to
Survex format and processed them natively, and with scagua.279.0 fixed
in each case the maximum discrepancy between the two results is:

Moved by (-0.11,0.13,0.03): scagua.a.10

Which seems entirely plausible - I wouldn't expect exact agreement in
this case as some of the data has backsights and some doesn't.  In the
data from SCAGUA.th, Survex will treat the data with backsights as
slightly more accurate (because the average of two essentially
independent readings is expected to be more accurate than a single
reading) and that affects the distribution of loop misclosures.

Cheers,
Olly
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Re: [Therion] Wrong average calculation from compass/backcompass data

2018-05-17 Thread Evaristo Quiroga via Therion 

Hi,

Ok OIly and Wookey, you are right, my formula has not been very lucky. 
It was an attempt to understand what error he was experiencing when 
compiling data with fore/back bearings. I found a large difference in 
loop closure error between Auriga (2.85 m in 1967m loop), Compass (2.9m) 
and Therion (14m).


Debugging the compilation I have found that the data transferred to 
Survex (data.svx), don't have sense to me. I have searched in the code 
source and found the complicated formula.
I made my own formula in a Excell, and calculate the average. With this 
I have detected a strong magnetic anomaly in one leg (Auriga has this 
bearing manually discarded, and the translation to Compass was OK, but 
to Therion the fore-bearing was translated with a 0, a 56 degrees 
difference with the inverse back-bearing). After to correct the magnetic 
anomaly and to calculate the fore-bearing with the inverse back-bearing, 
the loop error it's OK too in Therion (2.9m).


Only that it was necessary to understand what numbers Therion was going 
through to Survex, and that some degrees were deviating from those 
calculated manually. With the two files attached in the previous message:

    -a file with magnetic declination to 0 and fore/back bearings
 -a file with DM=0 and my average bearings.

I have compared the results, that are the same. After looking carefully 
at the files and the compilation log, I found the difference. The data 
transferred to Survex are:  bearing - magnetic declination - meridian 
convergence.   These two components are what made me see different data 
between those calculated by Therion and those calculated manually.


After some more checks, I have verified that Therion is correctly 
calculating the average between fore/back bearings. MY MISTAKE. The 
issue is closed.


Best regards and thanksfor the patience.

Evaristo.


El 17/05/2018 a las 15:02, Wookey via Therion escribió:

On 2018-05-17 09:25 +0200, Evaristo Quiroga via Therion wrote:

El 17/05/2018 a las 0:36, Olly Betts escribió:
 I think the formula is too complicated. I purpose a simpler formula, 
like:
             If bearing <=180
                       AverageBearing =  (bearing + (backbearing 
-180))/2
                 else
                       AverageBearing = (bearing + (backbearing +180))/2

 Your proposed formula gives wrong answers in some cases - consider:

 bearing = 80, backbearing = 0

 These give AverageBearing = (80 + 0 - 180) / 2 = -50 (equivalent to
 310), but this should be 130 (average of 80 and 180).


In this case is not a problem with my formula, is a serious magnetic anomaly
(100 degrees difference)  and the program should to stop and to send a warning.

Yes a warning should probably be issued about poor data, but it _is_ a
problem with your formula. It's just an example showing that all cases
have to be dealt with correctly, including the wrap-around at 0/360
(or 0/400 for grads) and your simplified formula doesn't.

An example with a much smaller difference between back and foresight
could still be constructed to show the issue:

Fore: 175, Back: 0 AverageBearing= (175+0-180)/2 = -2.5. That's
wrong. It should be 177.5 in this case.

Wookey


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Re: [Therion] Wrong average calculation from compass/backcompass data

2018-05-17 Thread Wookey via Therion 
On 2018-05-17 09:25 +0200, Evaristo Quiroga via Therion wrote:
> El 17/05/2018 a las 0:36, Olly Betts escribió:

> I think the formula is too complicated. I purpose a simpler formula, 
> like:
>             If bearing <=180
>                       AverageBearing =  (bearing + (backbearing 
> -180))/2
>                 else
>                       AverageBearing = (bearing + (backbearing 
> +180))/2
> 
> Your proposed formula gives wrong answers in some cases - consider:
> 
> bearing = 80, backbearing = 0
> 
> These give AverageBearing = (80 + 0 - 180) / 2 = -50 (equivalent to
> 310), but this should be 130 (average of 80 and 180).
> 
> 
> In this case is not a problem with my formula, is a serious magnetic anomaly
> (100 degrees difference)  and the program should to stop and to send a 
> warning.

Yes a warning should probably be issued about poor data, but it _is_ a
problem with your formula. It's just an example showing that all cases
have to be dealt with correctly, including the wrap-around at 0/360
(or 0/400 for grads) and your simplified formula doesn't.

An example with a much smaller difference between back and foresight
could still be constructed to show the issue:

Fore: 175, Back: 0 AverageBearing= (175+0-180)/2 = -2.5. That's
wrong. It should be 177.5 in this case.

Wookey
-- 
Principal hats:  Linaro, Debian, Wookware, ARM
http://wookware.org/


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Re: [Therion] Wrong average calculation from compass/backcompass data

2018-05-17 Thread Martin Sluka via Therion 

> 17. 5. 2018 v 9:25, Evaristo Quiroga via Therion :
> 
> In this case is not a problem with my formula, is a serious magnetic anomaly 
> (100 degrees difference)  and the program should to stop and to send a 
> warning. 

Evaristo, 

Therion is a program to interprete your data, not to solve problems with your 
data.

It is your responsibility what the data you import into Therion. 

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Re: [Therion] Wrong average calculation from compass/backcompass data

2018-05-17 Thread Evaristo Quiroga via Therion 

Hi Olly,

El 17/05/2018 a las 0:36, Olly Betts escribió:



I think the formula is too complicated. I purpose a simpler formula, like:
             If bearing <=180
                       AverageBearing =  (bearing + (backbearing -180))/2
                 else
                       AverageBearing = (bearing + (backbearing +180))/2

Your proposed formula gives wrong answers in some cases - consider:

bearing = 80, backbearing = 0

These give AverageBearing = (80 + 0 - 180) / 2 = -50 (equivalent to
310), but this should be 130 (average of 80 and 180).


In this case is not a problem with my formula, is a serious magnetic 
anomaly (100 degrees difference)  and the program should to stop and to 
send a warning.




The therion formula is attempting to average the angles by trigonometry,
which seems a reasonable approach (though probably slower than trying to
average more directly like you're suggesting).  It looks essentially
correct to me, though it's a bit oddly written since cos(90 - x) is
sin(x), sin(90 - x) is -cos(x), 90 - atan2(y,x) is atan2(x,y) (possibly
+/- a multiple of 360).  But if I work it out with a calculator for
236.8 and 56.8 then I do get 236.8.


In the afternoon I have detected a strong anomaly problem in one station 
and corrected manually the data. Now the loop error is similar to Auriga 
and Compass (2.9m for a 1967m loop). But I have to check if Therion do 
the correct average calculation.




If it's still not working with the declination set to zero, perhaps
you should show us a complete small example we can process to see
what is going on?


I attach the original file with the fore/back sight (SCAGUA.th) and a 
manually averaged  (SCAGUA_avg.th) to compare if Survex and Therion work 
well. The error loop is similar between the two files (2,9m) but I have 
to check if the station are positioned at the same coordinates.


Regards,

Evaristo.


encoding  utf-8
survey SCAGUA
# Auriga 2.42, 2018-05-16T06:54:45Z

centerline # 09.10.10

date 2010.9.4
units tape meters
units compass degrees
units clino degrees
units backcompass degrees
units backclino degrees

#declination 0.00 degrees

extend right

station 279.0 "SO-279" entrance

data normal from to length compass backcompass clino backclino left right up 
down
279.0 -  0.000.000.00 0.000.000.00  
  0.000.000.00 
279.0279.0A  2.33   236.856.8-11.411.40.00  
  0.000.000.00 # .superficie
   279.0A 279.1  4.51   163.2   343.2-32.232.20.00  
  0.000.000.00 # .superficie hasta anclaje desviador
279.1 279.2 12.41 1.5   181.5-77.777.70.00  
  0.000.000.00 
279.2 279.3  1.95   212.233.1-17.716.60.00  
  0.000.000.00 
279.3 279.4  3.58   340.6   160.6-32.932.90.00  
  0.000.000.00 
279.4 279.5  1.96   317.9   138.4-30.430.50.00  
  0.000.000.00 
279.5 279.6  1.27   250.968.3-31.831.10.00  
  0.000.000.00 # Fisura
279.6 279.7  0.71   339.5   159.5-12.412.40.00  
  0.000.000.00 # Fisura
279.7 279.8  2.31   215.635.6-10.410.40.00  
  0.000.000.00 # Lago bifurcacion
279.8 279.9  5.57   354.6   174.6 -4.1 4.10.00  
  0.000.000.00 # Lago derecho
279.8279.20  3.98   158.7   339.6 -9.910.50.00  
  0.000.000.00 # Seguimos el.Lago a izkierda. Bifuracion lago a derecha
279.9279.10 11.24   329.5   149.5 -4.0 4.00.00  
  0.000.000.00 # Lago
   279.10279.11  9.81 3.5   183.5  3.3-3.30.00  
  0.000.000.00 # Lago sifonado a12 metros
   279.20   279.20A  3.44   221.941.9-11.811.80.00  
  0.000.000.00 # Inicio otra galeria lago a derecha
   279.21279.22  7.00   176.7   357.2 -2.8 2.50.00  
  0.000.000.00 
   279.22279.23  6.49   109.6   290.5  0.6-0.60.00  
  0.000.000.00 
   279.23279.24 16.34   134.5   315.0  1.6-2.00.00  
  0.000.000.00 # Lago. En la estacion 2 pequeñas galerias bajas a 
derecha
station 279.24 continuation
   279.23279.44  2.19   166.0   345.9 -7.0 7.30.00  
  0.000.000.00 # Lago
   279.24279.25  3.6623.0   202.6  2.5-2.90.00  
  0.000.000.00 # Lago
   279.25279.26  6.6787.2   267.0 -0.3 0.00.00  
  0.000.000.00 # Lago. En estacion fisura a derecha
station 279.26 continuation
   279.26279.27  8.0689.7   270.0 -0.7 0.70.00  
  0.000.000.00 # Lago. EN la estacion galeria

Re: [Therion] Wrong average calculation from compass/backcompass data

2018-05-16 Thread Olly Betts via Therion 
On Wed, May 16, 2018 at 04:45:54PM +0200, Evaristo Quiroga via Therion wrote:
> I think the problem is the average calculation formula in "thdb1d.cxx"
> 
> >// check backwards compass reading
> >    if ((lei->data_type == TT_DATATYPE_NORMAL) ||
> >    (lei->data_type == TT_DATATYPE_DIVING) ||
> >    (lei->data_type == TT_DATATYPE_CYLPOLAR)) {
> >    if (!thisnan(lei->backbearing)) {
> >    if (thisnan(lei->bearing)) {
> >  lei->backbearing -= 180.0;
> >  if (lei->backbearing < 0)
> >    lei->backbearing += 360.0;
> >  lei->bearing = lei->backbearing;
> >    }
> >    else {
> >  lei->backbearing -= 180.0;
> >  if (lei->backbearing < 0)
> >    lei->backbearing += 360.0;
> >                                    // calculate average of two angles
> >  //lei->bearing += lei->backbearing;
> >  //lei->bearing = lei->bearing / 2.0;
> >                                    double sumx, sumy;
> >                                    sumx = cos((90.0 -
> >lei->bearing)/180.0*THPI) + cos((90.0 - lei->backbearing)/180.0*THPI);
> >                                    sumy = sin((90.0 -
> >lei->bearing)/180.0*THPI) + sin((90.0 - lei->backbearing)/180.0*THPI);
> >                                    lei->bearing = 90.0 - (atan2(sumy,
> >sumx) / THPI * 180.0);
> >  if (lei->bearing < 0.0)
> >    lei->bearing += 360.0;
> >    }
> >  }
> >    }
> 
> I think the formula is too complicated. I purpose a simpler formula, like:
>             If bearing <=180
>                       AverageBearing =  (bearing + (backbearing -180))/2
>                 else
>                       AverageBearing = (bearing + (backbearing +180))/2

Your proposed formula gives wrong answers in some cases - consider:

bearing = 80, backbearing = 0

These give AverageBearing = (80 + 0 - 180) / 2 = -50 (equivalent to
310), but this should be 130 (average of 80 and 180).

The therion formula is attempting to average the angles by trigonometry,
which seems a reasonable approach (though probably slower than trying to
average more directly like you're suggesting).  It looks essentially
correct to me, though it's a bit oddly written since cos(90 - x) is
sin(x), sin(90 - x) is -cos(x), 90 - atan2(y,x) is atan2(x,y) (possibly
+/- a multiple of 360).  But if I work it out with a calculator for
236.8 and 56.8 then I do get 236.8.

If it's still not working with the declination set to zero, perhaps
you should show us a complete small example we can process to see
what is going on?

Cheers,
Olly
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Re: [Therion] Wrong average calculation from compass/backcompass data

2018-05-16 Thread Evaristo Quiroga via Therion 
I think Therion subtract the magnetic declination before to transfer 
data Survex. Now to compare better I have put magnetic declination to 0.



declination 0.00 degrees




Data transferred to Survex by the "data.svx" file

*data    normal    from    to    tape  compass    clino
    1    2    0.00    269.423853    0.00
    1    3    2.33    236.223853    -11.40
    3    4    4.51    162.623853    -32.20
    4    5    12.41    0.923853    -77.70
    5    6    1.95    212.073853    -17.15





You can see Therion do a wrong fore/back sight compass average 
calculation. The good data average are:


1     3    236.8     -11.4

3    4    163.2    -32

4    5    1.5        -77.7

5    6    212.65    -17.15


I think the problem is the average calculation formula in "thdb1d.cxx"


// check backwards compass reading
    if ((lei->data_type == TT_DATATYPE_NORMAL) ||
    (lei->data_type == TT_DATATYPE_DIVING) ||
    (lei->data_type == TT_DATATYPE_CYLPOLAR)) {
    if (!thisnan(lei->backbearing)) {
    if (thisnan(lei->bearing)) {
  lei->backbearing -= 180.0;
  if (lei->backbearing < 0)
    lei->backbearing += 360.0;
  lei->bearing = lei->backbearing;
    }
    else {
  lei->backbearing -= 180.0;
  if (lei->backbearing < 0)
    lei->backbearing += 360.0;
                                    // calculate average of two angles
  //lei->bearing += lei->backbearing;
  //lei->bearing = lei->bearing / 2.0;
                                    double sumx, sumy;
                                    sumx = cos((90.0 - 
lei->bearing)/180.0*THPI) + cos((90.0 - lei->backbearing)/180.0*THPI);
                                    sumy = sin((90.0 - 
lei->bearing)/180.0*THPI) + sin((90.0 - lei->backbearing)/180.0*THPI);
                                    lei->bearing = 90.0 - (atan2(sumy, 
sumx) / THPI * 180.0);

  if (lei->bearing < 0.0)
    lei->bearing += 360.0;
    }
  }
    }


I think the formula is too complicated. I purpose a simpler formula, like:
            If bearing <=180
                      AverageBearing =  (bearing + (backbearing -180))/2
                else
                      AverageBearing = (bearing + (backbearing +180))/2

Regards,

Evaristo.
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Re: [Therion] Wrong average calculation from compass/backcompass data

2018-05-16 Thread Evaristo Quiroga via Therion 

Hi,

I found that the error had been fixed in version 5.4.1



  Therion 5.4 (5.4.1 now 2017-04-18)


 *
bugs and issues fixed:
27. invalid compass/backcompass averaging formula



But I am using the  "Therion 5.4.1+6884381 (2018-04-12)", were I have 
found the actual bug.


Evaristo.

El 16/05/2018 a las 14:17, Evaristo Quiroga via Therion escribió:

Hi,

I have data from a survey with fore/back sight compass and clino. I 
have detected a Therion bug calculating the average data, comparing 
with the error loops with Auriga, Visualtopo, Compass and Therion.


See the next compare.

Example from the data in .th file:

data normal from to length compass backcompass clino backclino left 
right up down
    279.0 -  0.00    0.00    0.00 0.00 0.00    
0.00    0.00    0.00    0.00
    279.0    279.0A  2.33   236.8    56.8 -11.4 11.4    
0.00    0.00    0.00    0.00 # .superficie
   279.0A 279.1  4.51   163.2   343.2 -32.2 32.2    
0.00    0.00    0.00    0.00 # .superficie hasta anclaje desviador
    279.1 279.2 12.41 1.5   181.5 -77.7 77.7    
0.00    0.00    0.00    0.00
    279.2 279.3  1.95   212.2    33.1 -17.7 16.6    
0.00    0.00    0.00    0.00 



Data transferred to Survex by the "data.svx" file


*data    normal    from    to    tape  compass    clino
    1    2    0.00    268.348831    0.00
    1    3    2.33    235.148831    -11.40
    3    4    4.51    161.548831    -32.20
    4    5    12.41    359.848831    -77.70
    5    6    1.95    210.998831    -17.15



You can see Therion do a wrong fore/back sight compass average 
calculation. The good data average are:


1     3    236.8     -11.4

3    4    163.2    -32

4    5    1.5        -77.7

5    6    212.65    -17.15

The clino average seems OK.

Searching in the mail-list I have found the bug was reported before. I 
think is not corrected since then.


https://www.mail-archive.com/therion@speleo.sk/msg04660.html

Regards,

Evaristo.

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[Therion] Wrong average calculation from compass/backcompass data

2018-05-16 Thread Evaristo Quiroga via Therion 

Hi,

I have data from a survey with fore/back sight compass and clino. I have 
detected a Therion bug calculating the average data, comparing with the 
error loops with Auriga, Visualtopo, Compass and Therion.


See the next compare.

Example from the data in .th file:

data normal from to length compass backcompass clino backclino left 
right up down
    279.0 -  0.00    0.00    0.00 0.00    0.00    
0.00    0.00    0.00    0.00
    279.0    279.0A  2.33   236.8    56.8 -11.4    11.4    
0.00    0.00    0.00    0.00 # .superficie
   279.0A 279.1  4.51   163.2   343.2 -32.2    32.2    
0.00    0.00    0.00    0.00 # .superficie hasta anclaje desviador
    279.1 279.2 12.41 1.5   181.5 -77.7    77.7    
0.00    0.00    0.00    0.00
    279.2 279.3  1.95   212.2    33.1 -17.7    16.6    
0.00    0.00    0.00    0.00 



Data transferred to Survex by the "data.svx" file


*data    normal    from    to    tape  compass    clino
    1    2    0.00    268.348831    0.00
    1    3    2.33    235.148831    -11.40
    3    4    4.51    161.548831    -32.20
    4    5    12.41    359.848831    -77.70
    5    6    1.95    210.998831    -17.15



You can see Therion do a wrong fore/back sight compass average 
calculation. The good data average are:


1     3    236.8     -11.4

3    4    163.2    -32

4    5    1.5        -77.7

5    6    212.65    -17.15

The clino average seems OK.

Searching in the mail-list I have found the bug was reported before. I 
think is not corrected since then.


https://www.mail-archive.com/therion@speleo.sk/msg04660.html

Regards,

Evaristo.

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