How do I make a map?

Scanning, geo-referencing, conversion of existing maps for use with ttMaps.
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How do I make a map?

Postby KLR250 » 08 Feb 2020, 22:59

I have successfully installed a copy of ttMaps, and a copy of Blue Marble world map onto an old TomTom ONE that I own.
It all seems to work fine.
Given that success, I have ventured into the art of creating my own map to go with ttMAPs.
Unfortunately, all my efforts have been futile.
Perhaps someone can tell me where I have gone wrong.

Ultimately, I would like to create my own maps for off-road travel.
But to start, I will settle for making a map of an area I am familiar with.
So I have chosen to make a map of the eastern communities of the city of Ottawa, Canada.

This is what I have done…
First I opened my Windows10 webbrowser and navigated to Google Maps.
In Google Maps, I zoomed the map to reveal the eastern communities associated with Ottawa, Canada (I centred on the area called Cardinal Creek).
I then used the Windows10 Snipping tool to select an area of interest and saved it as a JPG file – this file will eventually become my map, I hope.

Next, I have installed “QGIS 3.4.14” (Madeira) with “GRASS 7.8.1” onto my computer.
In QGIS, I have OpenStreetMap (OSM) installed under “XYZ Tiles”
Under “XYZ Tiles”, I have also installed ‘Google Map’, ‘Google Road’, ‘Google Satellite’, ‘Google Terrain’
I select Google Map, and drag/drop this to my Layers banner.
Clicking on the Google Map in the Layers banner creates a map in the working area.
I then zoom the base map to reveal the eastern communities associated with Ottawa, Canada and center on the area aligned with the JPG that I made previously.
Checking the layer properties for this map, I find that it is in “EPSG:3857 – WGS 84 / Pseudo-Mercator”.
From the banner at the top of the page, I select Layer and Data Source Manager.
Under Raster Dataset, I search for the JPG file that I made, and select Add.
This attempts to open the Coordinate Reference System Selector screen, but I get a warning that the CRS is undefined and then it tries to default to “EPSG:3857 – WGS 84 / Pseudo-Mercator”.
So, it appears I need to georeference my JPG file.
At the top of the page, under Plugins, I select “Manage and Install Plugins” and search for ‘georef’.
I then place a check mark next to the plugin called “Georeferencer GDAL”.
Next I go to the top banner, select Raster and then select Georeferencer.
The Georeferencer opens with a blank sreen, so I go to Open Raster and then find my JPG file, which then opens in the Georeferencer.
At the top of the page, under Settings, I select Raster Properties, and navigate to Source. Here I set the coordinate reference system to the same as the base map - “EPSG:3857 – WGS 84 / Pseudo-Mercator”
I then add 4 GCP points, with each one being taken from the base map.
Then I select the Start Georeferencing button.
It asks for some info on transformation setting (I went with: Thin Plate Spline, Nearest neighbor, CRS same as base map, no compression, Load into QGIS, and output raster name with a TIF extension).
I then select the Start Georeferencing button. It reports that it was a success.
I close the Georeferencer.
Looking at the layers, I can see that my georeferenced TIF file aligns very well with the base map.

Next I need to change my TIF file into an ECW file.
I have downloaded “FWTools 2.4.7”
I copy my new TIF file to the folder C:\Program Files (86)\FWTools2.4.7\Bin
In the Windows10 Start menu, I navigate to the “FWTools Shell” which opens a command prompt at the following directory - C:\Program Files (86)\FWTools2.4.7\
I type “cd bin” and now I am in the directory - C:\Program Files (86)\FWTools2.4.7\Bin
Now I run the following command, making sure my input and output file names are different –
gdal_translate -of ECW cardinalcreekmod.tif cardinalcreektran.ecw
The conversion is successful (For some reason the file is placed elsewhere in my computer, but searching for *.ecw will find it).

I now connect my TomTom ONE, open it as a memory device, navigate to ttMaps\Maps where I create a sub-directory with the same name as my new ECW file - cardinalcreektran.
Into this directory I place a copy of my ECW file.
I then restart the TomTom ONE, and navigate to the map…
BUT IT DOESN’T WORK – just a blank screen.

What am I doing wrong?
Anyone?
KLR250
 
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Joined: 08 Feb 2020, 22:10

Re: How do I make a map?

Postby jcr83 » 09 Feb 2020, 22:46

I can already see two mistakes:
- in the gdal_translate command, you have forgotten to specify the datum and the projection
- you have forgotten to reindex the maps
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Re: How do I make a map?

Postby KLR250 » 10 Feb 2020, 03:27

Thank you for responding.

I tried to look up the instructions on the GDAL webpage. I'm not sure I understand them, but this is what I did...

I revised the gdal_translate command as follows...

gdal_translate -of ECW -a_srs EPSG:3857 Cardinal_modified.tif Cardinal_tran.ecw

It appears to have run acceptably.
I ran gdalinfo and got this....

C:\Program Files (x86)\FWTools2.4.7\bin>gdalinfo Cardinal_tran.ecw
Driver: ECW/ERMapper Compressed Wavelets
Files: Cardinal_tran.ecw
Cardinal_tran.ecw.aux.xml
Size is 696, 609
Coordinate System is:
PROJCS["WGS 84 / Pseudo-Mercator",
GEOGCS["WGS 84",
DATUM["WGS_1984",
SPHEROID["WGS 84",6378137,298.257223563,
AUTHORITY["EPSG","7030"]],
AUTHORITY["EPSG","6326"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.01745329251994328,
AUTHORITY["EPSG","9122"]],
AUTHORITY["EPSG","4326"]],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
PROJECTION["Mercator_1SP"],
PARAMETER["central_meridian",0],
PARAMETER["scale_factor",1],
PARAMETER["false_easting",0],
PARAMETER["false_northing",0],
EXTENSION["PROJ4","+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs"],
AUTHORITY["EPSG","3857"],
AXIS["X",EAST],
AXIS["Y",NORTH]]
Corner Coordinates:
Upper Left ( 0.0, 0.0)
Lower Left ( 0.0, 609.0)
Upper Right ( 696.0, 0.0)
Lower Right ( 696.0, 609.0)
Center ( 348.0, 304.5)
Band 1 Block=696x1 Type=Byte, ColorInterp=Red
Overviews: arbitrary
Band 2 Block=696x1 Type=Byte, ColorInterp=Green
Overviews: arbitrary
Band 3 Block=696x1 Type=Byte, ColorInterp=Blue
Overviews: arbitrary

I copied the file into a directory on my TomTom …
>ttMaps>Maps>Cardinal_tran

But when I try to run the TomTom, I get the error "WARNING Map Cardinal_tran.ecw not referenced".

Maybe I still have an error in the gdal_translate command?

Your help is greatly appreciated.
Thanks.
KLR250
 
Posts: 9
Joined: 08 Feb 2020, 22:10

Re: How do I make a map?

Postby KLR250 » 10 Feb 2020, 03:27

Oh - and yes I did reindex the maps.
KLR250
 
Posts: 9
Joined: 08 Feb 2020, 22:10

Re: How do I make a map?

Postby jcr83 » 10 Feb 2020, 08:20

Have you read the instructions on the ttMaps website: http://ttmaps.free.fr/en/convert_maps.html?
If your map is in the pseudo-mercator projection, you should use DATUM=WGS84 and PROJ=MRSPHERIC.
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Re: How do I make a map?

Postby jcr83 » 10 Feb 2020, 10:03

Alternately, if your map is supported by MOBAC, you could use this method:
http://ttmaps.free.fr/forums/viewtopic.php?f=57&t=86#p4703 which is much simpler than yours.
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Re: How do I make a map?

Postby KLR250 » 11 Feb 2020, 02:17

Again, thank you for replying.

I have revised the command as follows...
gdal_translate -of ECW -co DATUM=WGS84 -co PROJ=MRSPHERIC Cardinal_modified.tif Cardinal_tran.ecw

The code runs fine.
I ran gdalinfo on the new file, and compared the info on this latest attemoy to that of my last attempt.
The info is identical.

I loaded it into the TomTom, and restarted it -- no errors.

I navigated to the map directory and re-indexed.

Once it had sufficient satellites - surprise - IT WORKS !!

So - what makes the difference ???
I have no clue. Particularly since a comparison of the gdalinfo for both this version and my last version were the same.
KLR250
 
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Re: How do I make a map?

Postby KLR250 » 11 Feb 2020, 02:22

Anyone new to map-making (like me) that is struggling with GDAL (like me) might find the following link helpful...
https://medium.com/planet-stories/a-gen ... 253eb96082

This website certainly helped cleared up many questions (not all, but many).
KLR250
 
Posts: 9
Joined: 08 Feb 2020, 22:10

Re: How do I make a map?

Postby KLR250 » 11 Feb 2020, 02:32

Okay - so now that we have solved that problem (thank you JCR83 for steering me), why can't I zoom in/out.

My map has one size.

The +/- magnifying glasses are absent.
KLR250
 
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Re: How do I make a map?

Postby jcr83 » 11 Feb 2020, 08:54

KLR250 wrote:So - what makes the difference ???
I have no clue. Particularly since a comparison of the gdalinfo for both this version and my last version were the same.


The difference resides in the metadata. Try this command:

Code: Select all
gdalinfo -mdd ECW Cardinal_tran.ecw

Driver: ECW/ERDAS Compressed Wavelets (SDK 3.x)
Files: 0.ecw
Size is 256, 256
Coordinate System is `'
Origin = (-20037508.342789243906736,20037508.342789243906736)
Pixel Size = (156543.033928040968021,-156543.033928040968021)
Metadata:
COLORSPACE=RGB
COMPRESSION_RATE_TARGET=20
VERSION=2
Metadata (ECW):
PROJ=MRSPHERIC
DATUM=WGS84

UNITS=METERS
Corner Coordinates:
Upper Left (-20037508.343,20037508.343)
Lower Left (-20037508.343,-20037508.343)
Upper Right (20037508.343,20037508.343)
Lower Right (20037508.343,-20037508.343)
Center ( 0.0000000, 0.0000000)

KLR250 wrote:The +/- magnifying glasses are absent.

By default, the map is displayed at maximum scale, so you can't zoom in. But you can zoom out, then zoom in.
Your screen should look exactly like this one:

Image
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