Hello DNRGPS,


It looks like there is a show-stopper bug in DNRGPS.

Bug report 161 (reported over 4 months ago) and bug report 208 are
describing the same problem in DNRGPS.


When making a gps track, the lat/lon/time of a trackpoint must be
correct. These three measurements must be accurate. Everything
starts from the assumption that the three basic properties
lat/lon/time of a gps point are accurate.

Something happened in DNRGPS that broke the basic assumptions
about an accurate track point.

To demonstrate the show stopper:

1) get a Garmin unit that allows direct access to the gpx file,
such as Garmin Foretrex 301.

2) get a copy of the last version of DNR GARMIN, which is 5.4.1.

3) get a copy of the newest version of DNRGPS, which is 6.0.0.11


Make a sample track and compare the results from all three tests.

DNRGPS 6.0.0.11 is writing the wrong Z time for the gps points.
DNRGPS is violating the assumption of a accurate measurement of
a gps point.



Below are the results from my simple test:


Test1) From Current.gpx file copied directly from the Foretrex 301:

<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<gpx xmlns="http://www.topografix.com/GPX/1/1" xmlns:gpxx="http://www.garmin.com/xmlschemas/GpxExtensions/v3" xmlns:gpxtpx="http://www.garmin.com/xmlschemas/TrackPointExtension/v1" creator="Foretrex 301" version="1.1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd http://www.garmin.com/xmlschemas/GpxExtensions/v3 http://www.garmin.com/xmlschemas/GpxExtensions/v3/GpxExtensionsv3.xsd">
<metadata>
<link href="http://www.garmin.com">
<text>Garmin International</text>
</link>
<time>2012-07-25T21:55:45Z</time>
</metadata>
<trk>
<name>ACTIVE LOG: 21 JUL 2012 08:08</name>
<trkseg>
<trkpt lat="31.479664" lon="-83.502811">
<ele>129.43</ele>
<time>2012-07-21T12:08:33Z</time> <==== correct Z time
</trkpt>
<trkpt lat="31.479664" lon="-83.502811">
<ele>129.43</ele>
<time>2012-07-21T12:08:34Z</time> <==== correct Z time
</trkpt>
<trkpt lat="31.479665" lon="-83.502811">
<ele>129.43</ele>
<time>2012-07-21T12:08:35Z</time> <==== correct Z time
</trkpt>



Test2) From DNR Garmin 5.4.1:

<?xml version="1.0"?>
<gpx
version="1.0"
creator="DNRGarmin - http://www.dnr.state.mn.us/mis/gis/tools/arcview/extensions/DNRGarmin/DNRGarmin.html"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://www.topografix.com/GPX/1/0"
xsi:schemaLocation="http://www.topografix.com/GPX/1/0 http://www.topografix.com/GPX/1/0/gpx.xsd">
<author>FRANK</author>
<time>2012-07-25T18:02:43Z</time>
<trk>
<name>ACTIVE LOG: 21 JUL 2012 08:08</name>
<trkseg>
<trkpt lat="31.479664" lon="-83.502811">
<ele>129.43</ele>
<time>2012-07-21T12:08:33Z</time> <==== correct Z time
<name>ACTIVE LOG: 21 JUL 2012 08:08</name>
<src>Foretrex 301</src>
</trkpt>
<trkpt lat="31.479664" lon="-83.502811">
<ele>129.43</ele>
<time>2012-07-21T12:08:34Z</time> <==== correct Z time
<name>ACTIVE LOG: 21 JUL 2012 08:08</name>
<src>Foretrex 301</src>
</trkpt>
<trkpt lat="31.479665" lon="-83.502811">
<ele>129.43</ele>
<time>2012-07-21T12:08:35Z</time> <==== correct Z time
<name>ACTIVE LOG: 21 JUL 2012 08:08</name>
<src>Foretrex 301</src>
</trkpt>



Test3) From DNRGPS 6.0.0.11:


<?xml version="1.0" encoding="UTF-8"?>
<gpx version="1.1" creator="GDAL 1.9.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ogr="http://osgeo.org/gdal" xmlns="http://www.topografix.com/GPX/1/1" xsi:schemaLocation="http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd">
<metadata>
<bounds minlat="31.479664000000000" minlon="-83.503015000000005" maxlat="31.491755999999999" maxlon="-83.490015999999997" />
</metadata>
<trk>
<name>ACTIVE LOG: 21 JUL 2012</name>
<trkseg>
<trkpt lat="31.479664" lon="-83.502811">
<ele>129.43</ele>
<time>2012-07-21T08:08:33Z</time> <==== WRONG Z time
<name>T1</name>
<type>TRACK</type>
<extensions>
<ogr:lat>31.479664</ogr:lat>
<ogr:lon>-83.502811</ogr:lon>
<ogr:y_proj>31.479664</ogr:y_proj>
<ogr:x_proj>-83.502811</ogr:x_proj>
<ogr:new_trk>True</ogr:new_trk>
<ogr:new_seg>True</ogr:new_seg>
<ogr:model>garmin Foretrex 301</ogr:model>
<ogr:ltime>2012/07/21 08:08:33</ogr:ltime>
</extensions>
</trkpt>
<trkpt lat="31.479664" lon="-83.502811">
<ele>129.43</ele>
<time>2012-07-21T08:08:34Z</time> <==== WRONG Z time
<name>T1</name>
<type>TRACK</type>
<extensions>
<ogr:lat>31.479664</ogr:lat>
<ogr:lon>-83.502811</ogr:lon>
<ogr:y_proj>31.479664</ogr:y_proj>
<ogr:x_proj>-83.502811</ogr:x_proj>
<ogr:new_trk>False</ogr:new_trk>
<ogr:new_seg>False</ogr:new_seg>
<ogr:model>garmin Foretrex 301</ogr:model>
<ogr:ltime>2012/07/21 08:08:34</ogr:ltime>
</extensions>
</trkpt>
<trkpt lat="31.479665" lon="-83.502811">
<ele>129.43</ele>
<time>2012-07-21T08:08:35Z</time> <==== WRONG Z time
<name>T1</name>
<type>TRACK</type>
<extensions>
<ogr:lat>31.479665</ogr:lat>
<ogr:lon>-83.502811</ogr:lon>
<ogr:y_proj>31.479665</ogr:y_proj>
<ogr:x_proj>-83.502811</ogr:x_proj>
<ogr:new_trk>False</ogr:new_trk>
<ogr:new_seg>False</ogr:new_seg>
<ogr:model>garmin Foretrex 301</ogr:model>
<ogr:ltime>2012/07/21 08:08:35</ogr:ltime>
</extensions>
</trkpt>





This is a show stopper defect that needs to be corrected in the
next release. Other programs that use the output from DNRGPS
assume the three basic reading, lat/lon/time, are accurate.
Indeed, on the EXIFTOOL forum, I asked the author of that
program to check his work. I assumed the output from
DNRGPS was correct. It turned out that DNRGPS is wrong.


Cheers,
Frank Davis