XPost: alt.comp.freeware, sci.geo.satellite-nav
On Sat, 23 Mar 2024 08:43:53 -0800, Bill Bradshaw wrote:
Is this about the right sequence to use those USGS geo PDFs with ozi?
1. Convert USGS geo PDF maps to native ozi explorer geo TIF files
2. Convert your GPX tracks to native ozi explorer plt tracks
I assume you using Ozi to import your GPX files.
It is under the Load Button.
Thanks for the advice where there isn't a direct "Load" button in Windows OziExplorer 3.95.6f but there is a "File > Load from file" which can take a
plt track or a wpt file but not a gpx track (and a evt and txt file too).
There is an import though for GPX & KML in the OziExplorer 3.95.6f menu.
"File > Load from file > Import GPX file"
I imported the GPX file output by the Android BasicAirData GPS Logger app.
Now I just have to put a geotagged topo map underneath as the map data.
3. Display the converted plt track on the ozi TIFF or OZF4 topo map
There are a lot of other things you can do. If you download and install
DEMs you can plot your trail profile and also other info.
Thanks for the advice where I just now had to look up what "DEMs" means.
https://help.locusmap.eu/topic/offline_dem_data_map
The main thing I want to do is display (and edit) the tracks saved by the Android open source gps logger app offline on Windows (or on Android).
To display the tracks on a map, I downloaded custom USGS topo areas.
https://www.usgs.gov/tools/national-map-viewer
But I also downloaded specific USGS topo quadrangles.
https://apps.nationalmap.gov/downloader/
That provided me with georeferenced topo PDFs using the instructions here.
https://apps.nationalmap.gov/help/The%20National%20Map%20Viewer%20Quick%20Start%20Guide.htm
Since OziExplorer won't seem to take georeferenced PDFs, I used the
converter on the web site to convert them to georeferenced TIFFs.
./image_convert/ImageConvertOzi.exe
Which ran the following command in the Windows command window.
.\gdal_translate -of GTiff -co COMPRESS=LZW -co "TFW=YES"
"c:\ozi\usgs01.pdf" "c:\ozi\\ozi_converted\usgs01.tif"
.\gdal_translate -of GTiff -co COMPRESS=LZW -co "TFW=YES"
"c:\ozi\usgs02.pdf" "c:\ozi\ozi_converted\usgs02.tif"
Thankfully all USGS PDF topographic maps are easy to calibrate because each corner is already marked with the DMS geolocated latitude and longitude.
Where an added complication was OziExplorer expects degrees decimal minutes which necessitated an additional conversion when stitching TIFs together.
I was then able to load the TIF into OziExplorer Click to calibrate.
File > Load & Calibrate Map Image
At that point I needed to upload the GPX tracks but I didn't know about
your suggestion that OziExplorer would upload GPX tracks directly.
So I had already run GpsBabel to convert the GPX track into PLT tracks.
I only used ozi explorer on Android & Windows for a few minutes so I
may have some of that wrong as ozi does things different than most
apps do.
But did I get anything wrong above in what I surmised from the ozi
site?
You definitely got everything. I do not remember how many calibration
points the converter puts in the *.map file but you can always add calibration points through the program (maybe only registered?). I always use at least 4 points with one at each map corner. If you get into this you probably will move on to stitching usge maps together. That is a whole new process.
The stitching wasn't that much of a problem nor was the calibration (other
than having to convert from USGS DMS to OziExplorer DdM for no good reason)
but it is odd so many special formats are needed just to use OziExplorer.
Do you know why OziExplorer natively uses PLT instead of GPX tracks?
Or why OziExplorer natively uses geocalibrated TIFF/BMP instead of geoPDFs?
Also I found out later that I could use Google topographical maps instead
of USGS topographical maps, but Google's topo maps are terribly inaccurate.
https://www.treasurenet.com/threads/using-google-maps-with-oziexplorer.269922/ So it's just nice to know but Google maps can't compete with the USGS maps.
I do have the android version on my phone.
I did install the Android OziExplorer APK whose interface showed a colorful world map (of Africa & Europe) but it wouldn't even scroll to the Americas.
So I killed it and decided to concentrate first on the PC software tools.
Thanks for your advice as I've only used OziExplorer for a total of about
an hour or two but I can see, after all the tedious conversions, it can be useful software for displaying tracks on an underlying USGS geoTIFF
composite which is available for from the USGS for anywhere in the USA.
I never did get the GPX to show unless I converted GPX to the PLT format.
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