.. _add_wtpoints:

Adding watertrack calibration points if the ship was slow
---------------------------------------------------------------


**Question**:

I have a UHDAS+CODAS Python processing directory with lots of short,
straight segments, surveying a small feature at slow speeds.  How
can I increase the number of watertrack points?

**Answer:**

Watertracking calibration consists of 3 steps:
In ``nav``" directory:

  (1) ``adcpsect as_nav.tmp`` # by default: whole cruise, run once



In ``cal/watertrk``

  (2) ``timslip timslip.tmp``  # by default: whole cruise, run once
  (3) ``python3 Wtplot_script.py`` # by default: whole cruise, run once

Step 1 is not changed.

Step 2 controls what points are extracted for watertrack.

Here's the 'diff' of the change ``timslip.tmp`` to make it get more points:

- first, copy to another name, eg ``timeslip_morepts.tmp``

- second, make these changes:

      (i)  change output file name
      (ii) change filtering
      (iii) change thresholds

..

To read the difference below,

 - "``<``"   refers to the first file, ``timeslip.tmp``
 - "``>``"   refers to the second file, ``timeslip_morepts.tmp``

Here's the difference between the two::

 ulili:(watertrk)$ diff timslip.tmp  timslip_morepts.tmp
 6c6
 <         output_file:        aship_7.cal
 ---
 >         output_file:        aship_5.cal   /* new name!! */
 9,20c9,20
 <         min_n_fixes=        7 /* 5 7 9 */
 <
 <         n_refs=             7 /* 5 7 9 */
 <
 <         i_ref_l0=           1
 <         i_ref_l1=           2 /* 1 2 3 */
 <         i_ref_r0=           5 /* 4 5 6 */
 <         i_ref_r1=           6 /* 4 6 8 */
 <
 <         up_thresh=          3.0        /* m/s */
 <         down_thresh=        3.0        /* m/s */
 <         turn_speed=         2.0        /* m/s */
 ---
 >         min_n_fixes=       5   /* 5 7 9 */
 >
 >         n_refs=            5   /* 5 7 9 */
 >
 >         i_ref_l0=              1
 >         i_ref_l1=          1   /* 1 2 3 */
 >         i_ref_r0=          4   /* 4 5 6 */
 >         i_ref_r1=          4   /* 4 6 8 */
 >
 >         up_thresh=          1.5        /* m/s */
 >         down_thresh=        1.5        /* m/s */
 >         turn_speed=         1.0        /* m/s */


Step 2, last part: run


     ``timslip timslip_morepts.tmp``

In this example, the output is a file called ``aship_5.cal``


Step 3: Alter ``Wtplot_script.py`` as one can for :ref:`Bottom Track <add_btpoints>`.

 - copy to ``Wtplot_script_morepts.py``
 - edit so the diff is

::
   <
   40c37
   < WT(cal_filename = 'aship_7.cal',
   ---
   > WT(cal_filename = 'aship_5.cal',     ## read new file
   42a40,42
   >   statsfile =  'adcpcal_morepts.out',   # different output
   >   ## add these here if you need to edit out some of the points you added:
   >   ##    clip_ph, clip_amp, clip_var, clip_dt, clip_u, clip_v

Then run


     ``python3 Wtplot_script_morepts.py``


and look at the output, both in the ascii file and the figures
(sorry, at the moment the png files will overwrite -- save copies
if you want to keep them)::


 ##------------- begin "timslip_morepts.tmp" ----------------------

         fix_file_type:      simple
         fix_file:           ../../nav/aship.gps

         reference_file:     ../../nav/aship.nav
         output_file:        aship_5.cal   /* new name!! */

         year_base=          2013
         min_n_fixes=       5   /* 5 7 9 */

         n_refs=            5   /* 5 7 9 */

         i_ref_l0=              1
         i_ref_l1=          1   /* 1 2 3 */
         i_ref_r0=          4   /* 4 5 6 */
         i_ref_r1=          4   /* 4 6 8 */

         up_thresh=          1.5        /* m/s */
         down_thresh=        1.5        /* m/s */
         turn_speed=         1.0        /* m/s */
         turn_thresh=        60         /* degrees */

         dtmax=              360        /* seconds, for 300-second ensembles */
         tolerance=          5.e-5      /* days, about 5 seconds */
         grid:               ensemble

         use_shifted_times?  no

 #----------------- end -------------------------------------


and::


 # --------------- begin Wtplot_script_morepts.py ----------------
 #!/usr/bin/env python

 ## written by quick_mplplots.py -- edit as needed:

 ## cruiseid      is 'ADCP'
 ## dbname        is 'aship'
 ## proc_yearbase is 2013
 ## printformats   is 'png'

 import matplotlib.pyplot as plt


 from pycurrents.adcp.quick_mplplots import Wtplot

 ## other options that can be chosen
 ##
 ##       name                    value
 ##      -------------          -----------
 ##        cruiseid             'ADCP
 ##        printformats         'pdf'
 ##        dpi                   100
 ##        outfilebase          'wtcal'
 ##        statsfile            'adcpcal.out'
 ##        comment              '#'
 ##        ddrange              'all'
 ##        clip_ph               3,
 ##        clip_amp              0.04
 ##        clip_var              0.05
 ##        clip_dt               60
 ##        clip_u                [-100,100]
 ##        clip_v                [-100,100]



 WT = Wtplot()
 WT(cal_filename = 'aship_5.cal',     ## read new file
   printformats = 'png',
   cruiseid = 'ADCP',
   statsfile =  'adcpcal_morepts.out',   # different output
   ## add these here if you need to edit out some of the points you added:
   ##    clip_ph, clip_amp, clip_var, clip_dt, clip_u, clip_v
   proc_yearbase = '2013')

 plt.show()
 #------------------------------ end-------------------------------



.. toctree::
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