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convert GPX files to GSSI's proprietary DZG format, and plot comparisons of marks in GPX and DZT/DZX files
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README.md

gpx2dzg

PyPI version License: GPL v3

This software takes GPS waypoint information stored in GPX files, tries to align waypoints with user marks in GSSI's proprietary DZX file format, and outputs the results to DZG (an ASCII file containing a mix of RMC and/or GGA NMEA strings and "NMEA-like" GSSI proprietary strings). The purpose of this translation is to artifically create GPS-aware ground-penetrating radar (GPR) projects.

At the moment (June 2019) this software has been tested with files created with SIR-3000 and SIR-4000 GSSI control units. The 3000 and 4000 control units record user marks in very different ways: the 3000 records them directly to the second row of the radar array, while the 4000 creates a proprietary XML file called DZX and records them as XML objects in that file. This software can handle both. If you used a 3000 during the survey, you can read the marks by pointing the software directly at your DZT file. If you used a 4000, you should point the software at the DZX file associated with the DZT. See usage for an explanation of how to do this in both Python and on the command line.

Note:

GPX and DZX or DZT files MUST contain the same number of marks for this process to work. That's because each GPS point has to be matched up with a scan number in order to tie the GPS points to marks made in the DZX or DZT by the control unit. If they do not, the script will bring up a plot showing GPX marks plotted by distance, DZX/DZT marks plotted by scan number, and velocity between GPX points for comparison. You can modify either GPX or DZX using a standard text editor, and add or remove marks based on your survey notes. If you're reading a DZT file from a SIR-3000 survey, you can remove marks 4, 5, and the mark second from the end in the mark list, by specifying drops=[3,4,-2] if you're using the python console, or -r 3,4,-2 if you're using the command line. Remember, the list index starts at 0, so drops=[3] or -r 3 will drop the 4th mark.

I urge you to take copious notes in the field so that you know if there will be errant marks you need to remove later. I will do what I can to help, but ultimately I am not responsible for missed GPS or GPR marks in your radar surveys (sorry!)

installation

simple install

If you've installed python packages before you may not need this. If you're uncomfortable installing python packages, read on. All requirements are on the Python Package Interface (PyPI), which means that you do not need to manually anything else in order for this to work (requirements should theoretically install automatically). Execute the following command in an Anaconda Prompt or bash terminal to install:

pip install gpx2dzg

installing development versions

If you wish to install the very latest commit from github (which may be more up-to-date than the version on PyPI but also may have more bugs), simply download this repository using the "Clone or download" button above. Unzip the package to your Downloads folder, then execute the following command in an Anaconda Prompt or bash terminal:

pip install ~/Downloads/gpx2dzg

If that doesn't work, you may need to unzip differently. Try making a folder called gpx2dzg in your Downloads folder, then unzip all of the contents of this package to it, so that setup.py is located at ~/Downloads/gpx2dzg/setup.py.

usage

in python

Note that although many of these examples use SIR-4000 DZX files, this program also works with DZTs created with the SIR-3000, which stores marks in the second row of the radar profile.

The following command will compare the DZX and GPX files, and if the mark numbers are the same, it will write a DZG file (write=True).

>>> import gpx2dzg.gpx2dzg as g2d
>>> g2d.convert(dzx='/path/to/dzx.DZX', gpx='/path/to/gpx.gpx', write=True)

However, write=True may not be the desired behavior if you would like to compare the mark points first. In that case, you'll want to specify plot=True instead to force a sanity check plot. Note: this will happen automatically if GPX and DZX mark numbers are not equal, because the software will not write a DZG in that case.

sanity check plotting

This software contains the ability to plot GPX and DZX marks next to each other, along with speed over ground, in order to visually check which points may have been missed or created erroneously in the field. As stated above, this will happen automatically if the mark numbers differ between the GPX and whichever GSSI file you're working with.

An example is shown below. This plot contains four axes:

  1. GPX marks plotted along a numberline depicting marks plotted by distance in meters along survey line.
  2. GPX marks plotted along a numberline depicting marks plotted by seconds elapsed along line.
  3. DZX or DZT marks plotted along a numberline depicting marks plotted by scan number.
  4. Speed (meters per second) between marks in GPX file, plotted as a function of seconds elapsed.

If you record files by time (i.e. a set number of scans per second), it will be helpful to compare plots 2 and 3. The better the mark points line up in plots 2 and 3, the better off you will be. If you record files by using a survey wheel or other Distance Measurement Instrument (DMI), you should compare plots 1 and 3.

Sanity check plot with differing mark counts

DZX/DZT point removal

You can remove mark points from the list of DZX or DZT marks by specifying drops=[4,5,-2]. It may be beneficial to do this and check the plot a couple of times until the GPS and SIR marks match up. Remember, the list index starts at 0, so drops=[3] or -r 3 will drop the 4th mark. Adding a negative number will remove from the end of the list, so drops=[3,-2] will remove both the fourth point in the list and the second to last point in the list. This software will not let you drop the first or last point (i.e. drops=[0] or drops=[-1]) since these are required to properly normalize the full extents of your DZT files.

In this case, we only need to drop the second-to-last point in order to get matching DZX and GPX mark counts.

>>> g2d.convert(dzx='/path/to/dzt.DZX', gpx='/path/to/gpx.gpx', plot=True, drops=[-2])

Note that the second to last point is removed in this second example.

Sanity check plot with identical mark counts

write results to a .DZG file

Add write=True to the function call. The program will not overwrite if there's a DZG already named the same as the DZT or DZX, instead it will name it something like dzt-gpx2dzg.DZG.

>>> g2d.convert(dzx='/path/to/dzt.DZX', gpx='/path/to/gpx.gpx', drops=[-2], write=True)

forcing a sanity check plot

To force the sanity check plot even if mark numbers are equal, simply add plot=True.

>>> g2d.convert(dzx='/path/to/dzx.DZX', gpx='/path/to/gpx.gpx', plot=True)

Sanity check plot with identical mark counts

This might not seem like a "sane" way to do a sanity check, but if you have a better idea I would love to hear from you.

on a bash or Anaconda Prompt command line

gpx2dzg -d /path/to/dzx.DZX -g /path/to/gpx.gpx

sanity check plotting

Simply add the -p flag.

gpx2dzg -d /path/to/dzx.DZX -g /path/to/gpx.gpx -p

DZX/DZT point removal

You can remove mark points from the list of DZX or DZT marks by adding the -r flag with a list of integers. Again, it may be beneficial to do this a couple of times to check that the GPS/SIR mark points in the plot match up the way you want them to. Remember, the list index starts at 0, so -r 3 will drop the 4th mark. Adding a negative number will remove from the end of the list, so -r 3,-2 will remove both the fourth point in the list and the second to last point in the list. This software will not let you drop the first or last point (i.e. -r 0 or -r -1) since these are required to properly normalize your DZT files.

Notice in this example that the value of -d can point to either a SIR-3000 DZT file or a SIR-4000 DZX file.

gpx2dzg -d /path/to/dzt.DZT -g /path/to/gpx.gpx -p -r 4,5,-2

write results to a .DZG file

Simply add the -w flag. The program will not overwrite if there's a DZG already named the same as the DZT or DZX, instead it will name it something like dzt-gpx2dzg.DZG.

gpx2dzg -d /path/to/dzt.DZT -g /path/to/gpx.gpx -p -r 4,5,-2 -w

usage notes:

If no GPX file is specified, the software will look for a GPX named the same as the DZX or DZT (for example, if the DZX/DZT is named file.DZX or file.DZT, the script will look for a file named file.gpx).

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