OpenStreetMaps not being seen on Nuvi 250W

[Darius]

I have a Nuvi 250W with UK and Europe maps - City Navigator Europe NT 2008.

I downloaded an OpenStreetMap gmapsupp.img for the UK from OpenMapChest. I saved it to SD Card in the \Garmin folder.

I went to Settings > ... > Map Info and ticked both maps.

Expected result: The newer OpenMapChest map will take precedence over the older City Navigator Europe NT 2008 map and I will be able to see new roads.

Actual result: I cannot see the new roads in OpenMapChest. When I scroll through the map to a recently constructed new road it does not appear.

I then unticked City Navigator Europe NT 2008 so just OpenMapChest was ticked. Scrolling over the map now finds the new road. I would be happy to leave it like this but ... I cannot search on postcode :-(

My question: How can I see the new roads on the OpenMapChest map while still keeping City Navigator Europe NT 2008 ticked because that allows me to search on postcode?

A workaround I am investigating is to add postcode search to the OpenMapChest map, either in the .img file or as a separate POI file.

I tried other downloads of gmapsupp.img but all gave the same result.

All ideas are welcomed!

A thought. My expectation that I can see both maps may be incorrect. If I can see only one map at any one time can I add? merge? the Nuvi City Navigator Europe NT 2008 map to/with the OpenMapChest map and create a single gmapsupp.img file on the SD Card. It will probably be too big to fit on the Nuvi itself.

Image of files on Nuvi

Image of file on SD Card

 

[Nuvi-Nebie]

When both maps are enabled the City navigator map is visible because it had a higher priority, you won't be able to see details from both maps at the same time, as far as I know it is not possible to merge maps so that details from both are visible the same time.

Open Street Maps do not contain postcode information so you will not be able to search for them while viewing OSM maps, there is a way around this however, enable the City Navigator map, search for a postcode and zoom into this location, then create a waypoint at the postcodes location by touching the screen location and selecting 'Save', you will now have a waypoint (Favourite) stored on your 250W, you can now enable the OSM map and recall the Favourite so that it's location is displayed on the OSM map

 

[Darius]

Many thanks. Your workaround is a good one so I will say this is Solved.

My errors were

• thinking that priority was set by map_date, and
  
• not realising it is the "very low content base map" which is overlaid by a more detailed map, and
• not realising the installed City navigator map has highest priority

I am 90% of the way to adding postcodes to gmapsupp.img as described in

https://wiki.openstreetmap.org/wiki/OSM_Map_On_Garmin/Postcode_Search_On_Garmin

I have created the XML file with the 2 million or so valid UK postcodes - I now just need to merge it with gmapsupp.img. I enjoy a challenge

The workaround of using POI isn't very good as a POI search is very so slow (minutes with a single file) and even splitting postcodes into many small csv files before converting to a .gpi file is still slow.

 

[Nuvi-Nebie]

I would be interested in seeing how you get on with this, it look interesting, another problem you may encounter is map stability when using OSM maps, I have them on my Nuvi56LM, but find that the satnav crashes occasionally when tracking your position, I have never really found out why

 

[Darius]

I will post my results.

I downloaded postcode data from the Office of National Statistics.

I used HJSplit to split the huge .csv file into 100MB chunks which Calc could process - it has a 1 million row limit.

I used LibreOffice Calc to delete the withdrawn postcodes and produce the .csv files (with a concatenating text strings trick to use node_ids greater than 2^64).

I wrote a few lines of QBasic to read the data in the csv files and write the XML code to the pattern in the post.

I used NotedPad++ to view the huge XML files and join them together.

Another option is to use Area Codes - that is AB12 instead of the full AB12 3CD - and create POIs - the files are much smaller.

All the software I used is free to download.

 

[Nuvi-Nebie]

I used HJSplit to split the huge .csv file into 100MB chunks which Calc could process - it has a 1 million row limit.

Yes I understand that the 16000 new covid cases the were recently 'lost' was due to some government official importing csv cases into an Excel spreadsheet using xls rather than xlsx format, the old xls format only uses the first 65K entries rather than 1 million