When a Garmin has multiple maps

[drossall]

For my birthday, a Garmin Edge Touring Plus arrived

This should be ideal for me - previously, I had an Etrex Vista HCx, so it's quite a move on.

Anyway, it came with some basic maps, so I put open maps onto it, which seem to be working fine. That set me thinking though - it's now got four maps all set to active, although I think the ones that were pre-installed were "outline" ones. Still not sure what the Garmin Cycle Map, or whatever it's called, really is.

So how does the unit handle having more than one active map for an area?

[Kim]

Maps have a value that determines which gets rendered on top of which. Gaps and transparency mean you see the one below. In practice this is only useful with the basemap (rendered at the very bottom, for areas your proper map doesn't cover) and things like the SMC contour and peaks overlay.

[tatanab]

So how does the unit handle having more than one active map for an area?

I have four maps on my Edge 800, but only keep one active.  Is there an advantage to having more than one active?

[frankly frankie]

If they are covering the same area, and more than one is routable, then having both active might not work too well with the routeing**.  Apart from that, it's just a bit of processor overhead I guess, and they're slow enough already.
However if they're covering different areas - eg one map for UK and another map for India - or if there is a non-routable transparent overlay (often contours) then it's OK to have more than one active.

** on the other hand, I have used a Garmin Metroguide map (routable) with a hole punched in it around the Heathrow area, and underneath that OSM (also routable) just in that area, because it is far more informative about terminal layouts etc.  And I have set the Etrex to route across that area crossing the map boundaries twice, and to my great surprise it was seamless.

[Kim]

Is there an advantage to having more than one active?

When they cover different areas (self-explanatory), or when one is transparent.  The SMC contour map is transparent, so you enable it at the same time as another map, and lo - you have a map with contours.

(Garmin City Navigator + the SMC contours is my preferred map for road cycling.  It's consistent and gives the right level of detail in urban areas.  I prefer OpenStreetmap if trying to follow a NCN route.)

[drossall]

Thanks all, so I'm probably best de-activating the maps that came with the unit. I've installed the whole UK from open maps, and I'm not going anywhere else soon...

[yoav]

The maps that came with my Garmin Edge Touring were Garmin's version of OSM (for Europe) so I'm not sure what the differences are between those and the OSM you can download freely. One advantage of sticking with the Garmin supplied maps is that Garmin Express will tell you when an update is available and do it.

[Feanor]

Some advantages of getting your own OSM maps are:

-There's a fair variety to choose from, and they offer different map features.
-You don't need to wait for Garmin's update cycle if there are changes in road layouts etc.

[PloddinPedro]

....... they offer different map features. .....

Not fully understanding how this all works, this is an aspect of OSM that I'm vaguely aware of but which I've never explored.

My foggy 'understanding' is that there's a database of hard information about actual physical roads, etc. and then separate 'overlays' created by different authors which when combined with the base data, deliver the map with an appearance chosen by the overlay author according to whatever he/she thinks looks/works best for a chosen purpose.

So one flavour of OSM might be optimised in its choice of say, colours for the different road sizes, for driving and another for cycling. Ditto for whether or not to include selected 'points of interest' - petrol stations for drivers, cafés for cycling for example.

If (?) this is correct, it leads me to think that there may be a version of OSM out there which would give me a version less cluttered but still with the fundamentals needed for cycling. Is my understanding correct or have I got the wrong end of the stick?

Having said that, I have to say that the "Cycle Map of Europe" (or however it's titled) that came bundled in my Edge 1000 seems to do a pretty good job, so perhaps I don't need to look further?

[frankly frankie]

Its more a question of filtering and styling the data to show only what you want, rather than adding overlays.  I have tried making an OSM map of footpaths and bridleways only, to combine with my Garmin roads-only map - but it was only partially successful, I was able to get rid of roads OK but I was unable to get rid of large area blocks denoting things like parks and industrial complexes.  Close, but no cigar.

[Feanor]

....... they offer different map features. .....

Not fully understanding how this all works, this is an aspect of OSM that I'm vaguely aware of but which I've never explored.

My foggy 'understanding' is that there's a database of hard information about actual physical roads, etc. and then separate 'overlays' created by different authors which when combined with the base data, deliver the map with an appearance chosen by the overlay author according to whatever he/she thinks looks/works best for a chosen purpose.

So one flavour of OSM might be optimised in its choice of say, colours for the different road sizes, for driving and another for cycling. Ditto for whether or not to include selected 'points of interest' - petrol stations for drivers, cafés for cycling for example.

If (?) this is correct, it leads me to think that there may be a version of OSM out there which would give me a version less cluttered but still with the fundamentals needed for cycling. Is my understanding correct or have I got the wrong end of the stick?

Having said that, I have to say that the "Cycle Map of Europe" (or however it's titled) that came bundled in my Edge 1000 seems to do a pretty good job, so perhaps I don't need to look further?

Yes, that's more or less right.
But as FF says, it's not so much overlays, but more control of the map rendering.

These are many elements in the map data, and you can control the rendering of these.
They can be rendered or not, and the style of the rendering can be changed.

Google on TYP files for some more detail.

[drossall]

If (?) this is correct, it leads me to think that there may be a version of OSM out there which would give me a version less cluttered but still with the fundamentals needed for cycling. Is my understanding correct or have I got the wrong end of the stick?

One thing to be said for the HCx that I have mislaid is that it used simplified maps that were more than adequate for following roads and turnings. I'll let you know after tomorrow whether I think the fuller maps on the Edge Touring Plus are a benefit or a hindrance

[Phil W]

Not just rendering but also routing. So you can decide what is routable, which types of roads / paths to route in preference to others. Which type of roads to avoid except in extremis etc.  So you may decide to turn off bridleways and off road NCN plus footpaths. Keep A roads as routable but low down on the preference list. You can also determine what is searchable etc.  The rendering is also more than just on and off. You can determine which features to render at certain zoom levels but also what to render something as. So an A road may be a simple black line when zoomed out but a nice red one like the OS style when zoomed further in etc.

[Feanor]

Yes indeed.

I was just trying to keep the reply as simple as possible without actually being wrong!

[PloddinPedro]

Google on TYP files for some more detail.

Not just rendering but also routing. So you can decide what is routable, which types of roads / paths to route in preference to others. Which type of roads to avoid except in extremis etc.  So you may decide to turn off bridleways and off road NCN plus footpaths. Keep A roads as routable but low down on the preference list. You can also determine what is searchable etc.  The rendering is also more than just on and off. You can determine which features to render at certain zoom levels but also what to render something as. So an A road may be a simple black line when zoomed out but a nice red one like the OS style when zoomed further in etc.

Crikey! Endless hours of mind-boggling education to endure (retires dazed!) Thanks (I think!)

[De Sisti]

Cheeky question here (sorry). Does the fact that Garmin Express doesn't see my newly purchased Touring Plus
have anything to do with the unit in Mass Storage mode?

[Feanor]

Cheeky question here (sorry). Does the fact that Garmin Express doesn't see my newly purchased Touring Plus
have anything to do with the unit in Mass Storage mode?

I'm not sure it has any other mode when connected to a PC.
If they are anything like the Edge 800 series which they are derived from, then they go into mass storage mode when you plug them into the PC.

Does the unit's display show it in connected-to-a-pc mode?
Does the PC (what OS? ) go bing-bong to indicate it's found a USB device?
Does the PC mount the device as a drive visible in Windows Explorer?

If it does all these things, then I'd expect GE to be able to find it.

[yoav]

The only thing I'd add is that I connect the Garmin, wait for it to show on the desktop as external drives (2) then fire up Garmin Express. I don't keep Garmin Express running all the time in the background (as it will by default) but close it down after I've finished using it and before I eject the drives.