How to shrink gmapsupp image file ?

Depends on which map you're talking about? Which GPS? Is the map installed on your PC and viewable in BaseCamp?

It's a built in Navigation system made by Garmin. I succeed in replacing the .img file but not this year.
I have basecamp but after a few hours trying without results, I think I'd better look for help...

How is the map normally updated on that device? If you use Express there should be an option to download to your PC for BaseCamp to use. Once there you can create smaller mapsets.

Normally it's a new CF card at the dealer (over $300.00). So, I Find a newer image file to replace the old one. Thath's it! But this time It"s a reduce sizer mather.

If not, My map has any accuracy. I tried many programs without finding the solution.

I've took a brief look at Express-map and it's looking a bit complicated for a newbie like me.

There must be an easier way...

Thanks again for your patience.

Sorry. If it's on a card I can't help. Someone else may know though.

Thanks anyways...

Hi, I'd like to help you but would need better information than the cryptic info above. Have you tried using the free Open Street maps ( http://garmin.openstreetmap.nl/ ) to install maps into BaseCamp and then selecting < 2GB of area to send to your card?

I too am trying to make my img file smaller. I have an eTrex 10 that I downloaded a topo file of North Carolina to use. The state map breaks up into smaller files. I loaded one file into my device and it shows the contour lines and roads in my area on the device correctly. I want to edit the files to only include the area I am planning to hike, such as South Mountain Park area only. When I select 'receive from device' to BaseCamp it doesn't use the topo map but displays a very basic map. I have 'Basic Map Only' deselected but that didn't change anything.

Is there a way to do this for the eTrex 10 or am I SOL. I did a lot of research before purchasing this unit. Most of what I read doesn?t seem to work now that I have the device.

Any help would be greatly appreciated.

You can't import a map from your device to BaseCamp. What you'll need to do is install the map to your PC for BaseCamp to use. Once you've done that you can use BaseCamp to install smaller portions of the map to your device, assuming of course it comprises numerous map tiles, which I suspect from your description it does.

This is a solution that I used some time ago for selecting a sub-area from img map:
1. Download and install GPSMapEdit (I believe it's free for non-commercial use).
2. Import the img file into GPSMapEdit.
3. Select the area of interest.
4. Trim the non-selected area.
5. Export the remaining area into Polish Format.
6. Compile the exported file into img using cgpsmapper.
7. Upload img file into device.

The procedure is tricky and requires some effort to understand the principles of garmin-formatted maps, but it's the only feasible way that I can think of. Since it was some time ago that I last performed this procedure, I cannot provide you with details on how to operate the GPSMapEdit software, nor where to find it (especially cgpsmapper might be tricky to find as it has been abandoned for a long time, I think).

Some remarks:

• The procedure will not work with locked maps. No chance. Forget it.
  
• The procedure becomes more complicated when the img file is in fact a multi-map file (like for example commercial maps found on some nuvi devices), as those do not work properly in GPSMapEdit. Unpacking the multi-map img into separate single-map img files is required, but I cannot recall the name of the tool I used to do that.
  
• Point 6 can sometimes fail for various reasons. In that case manual editing of the Polish Format file is required, but this is way beyond the scope of this forum.