Newbie Questions (Overlays-Map Editing)

[mac1234]

Recently purchased a Nuvi 500 for offroad use.  The plan is to use it up in the Sierra's to help navigate fire/logging roads etc.

The base 100k topo map is pretty much unusable for this as 90% of the fire/logging roads are not on it.  I expected this would be the case when purchased and have since purchased the 24k West Topo with WA,OR,CA,NV.

I am very suprised at how accurate the Garmin 24k West map is as it has the vast majority of roads I am looking for.  Only problem is the color of these roads is easily missed as they are dark grey on a dark green background making it very difficult to use unless zoomed in drastically.  Compound this with the obscene amount of clutter created by the topo lines and elevations and I am left with a tool that is almost unusable for what I am seeking.

So this is what I am wanting to do:

Open up the Garmin Topo 24k west maps in an editing program and then trace the roads I am needing.  Then I can save these traced roads as a separate map file and use it as an overlay or simply by itself, making the roads easier to see while zoomed out.  Ideally I would make my own new map with nothing but roads, lakes and streams but that can follow.

So my main question is first...Is this even possible to open an existing Garmin map and then edit or trace over it?  Second is what program/s will be needed.  I have a demo version of Mapwell 2009 now.

I know there is likely no short answer, but any guidance would be helpfull and appreciated.

[-Oz-]

Yes you can open it up; and you can probably extract the roads.  The hardest part will be figuring out which of the 100s of .img files has the area you're looking for.

I am pretty sure mapwel can't open the .img files (only export them) so you're gonna have to get the demo of gpsmapedit for that.

Now, the caveat: the Garmin maps are copyrighted so this could violate the terms of use.

[mac1234]

Thanks for the reply.

I have downloaded gpsmapedit and have attempted to open the Garmin IMG files.  Thing is, I can not find any files with the .IMG extension.  The only file I can open is the TDB file at the root of the mapset which allows me to see all of the individual IMG tiles for the covered area.  I can easily find the tiles I will need using this feature, however, I havent been able to figure out how to open these individual IMG files. 

Under the associated IMG folders in the Garmin directory are 6 file types DEM, LBL, NET, NOD, RGN and TRE files.  Does one of these need to be decompressed or are these files compiled through some process to create the IMG files?

Back to playing with it...

[mac1234]

Awesome, thats pretty much what I was initially thinking I would have to do, just wasn't sure exactly what tools or how I would go about it.  Your info gives me something to run with.  Also, need to point out if this would make the process easier, I am not concerend with roads being trackable they can simply be a static image that is accurate enough for me to use as a nav aid.

So tonight I will try tracing out the roads in MapSource, save as GPX file, then open this file in GPSMapEdit and convert the tracks to road to make an overlay.  Sounds simple enough, but I'm sure I'll run into something.

-Oz-:  Is it possible to open IMG files from the TOPO 24K mapset as this would be much easier to simply extract the roads somehow.  Like I said I am able to open the TDB file in MapEdit and it shows all of the 100+ tiles for the set and  they are listed as *.IMG files.  Maybe MapEdit simply interprets the files as IMG files?

thanks for the help men.

[mac1234]

Well thanks to your help, I successfully created a test overlay of logging roads for my AOI.  Now that I have the process down I will start playing with the various options and settings.

One question I do have is that I closely traced my test roads to be quite accurate with many points, but after converting to IMG using cgpsmapper with GPSMapEdit it removed many of the points resulting in a very jagged and unacurate road.  How can this be avoided, it appears there is a limit that it adjusts to during the compile?

As I write this I have just realised where the option to change this probably is.  I will test, but feedback is still appreciated.

Thanks