[Talk-us] Whole-US Garmin Map Update

[Greg Troxel]

Dave Hansen <dave at sr71.net> writes:

> I updated my whole-US map for Garmin devices.  It's stolen from the
> Cloudmade state gmapsupp images that you can find here:
>
> 	http://downloads.cloudmade.com/north_america/united_states/
>
> and pieced together with mkgmap and wget.  Just take the gmapsupp.img
> file from here:
>
> 	http://daveh.dev.openstreetmap.org/garmin/
>
> and put in the /garmin/ directory on your device (if you have an SD card
> unit).  I'll be updating these periodically as I feel the need.  I think
> I also have my methods down to a point where I could just script it and
> make these weekly or something, if anyone is interested.

I have wondered about making all-us garmin data, and think there might
be problems with the gmapsupp.img you made.  Perhaps I'm confused, but
I'm throwing these points out for discussion:

  --route is AFAIK not turned on in cloudmade, so those maps wouldn't be
  routable.  If cloudmade has enabled routing, that would be good to
  know.  (Plus there's the noname roads being big and red.)

  roads are disconnected at state boundaries due to being cut with a
  non-splitter tool.  (splitter has special logic to insert nodes on
  ways at tile boundaries.)  I think I had this problem when using
  e.g. massachusetts.osm.bz2 and vermont.osm.bz2 together into splitter
  - driving from central mass to vermont had routes reverting to basemap
  but when I crosssed into VT they became sensible.

  When making maps of a state, splitter makes tiles that fit the x/y
  bbox, and these will in general go beyond the state border.  When you
  do this with neighboring states, typically you'll get overlapping
  tiles that will have data in the state and no data out of state,
  mirror image.  It's not clear what the draw order is for areas covered
  by both tiles, but any particular order can't be right.

To make a gmapsupp.img for all of the US, I was going to get a US
extract of the planet, use splitter, and then use mkgmap with routing
enabled.  I would then use gmapibuilder to put into RoadTrip so I can
load the parts I want together with the proprietary map (for when I
actually have to get somewhere :-(). That should address all three
issues above.


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