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Author Topic: How map-files are organized on eTrex30 and how they are selected?  (Read 9338 times)

larshgf

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{} = folder
files in red = map-files
questions in blue - numbered

The folders in my etrex30 looks like this.....

Etrex30

{Documents}
{Files}
       {c} - css_files
      {j} - javascriptfil
      {m} - gif_files
      {pdf} - usermanual in different languages
                StartHere.html (choose language of manual)

{Garmin}
   {BirdsEye}
   {CustomMaps}
      Samos331.kmz
   {CustomSymbols}
   {ExtData}
   {Filters}
      {Geocache}
   {GPX} - contains tracks
      {Archive}
      {Current}
      SPOR-01-MAJ-12 211733.gpx
      etc
   {JPEG} - pictures
   {Profiles} - profiles
      {CustomMaps}
         Samos331.kmz
   {Text}
   gmapbmap.img
   gmaptz.img

MicroSD

{Garmin}
   gmapsupp.img
------------------------------------------------------------------
gmapbmap.img
= basic map of the whole world used for generel orientation
gmaptz.img
= (1) garmin timezone file (I do not know exactly how this works?)
gmapsupp.img
= AFAIK this file is a userfile placed on the microSD. I believe it can be composed of many different maps into on file. Lets assume that this file contains 4 different maps. Just an example.
(2) I wonder if somebody can explain how Garmin controls these maps in this single file?
(3) I know there is something called Family ID?
(4) And how can I as a user choose between the maps included in the gmapsupp.img file?
(5) Which utility program can I use to split my gmapsupp.img into the 4 maps and which program can add more maps into one gmapsupp.img file?

Samos331.kmz
= a map I made by scanning a samos map. If this is saved in {CustomMaps } as shown above I am able to see it.
(6) Is it possible to have more mapfiles in the {CustomMaps} folder and will I be able to choose which one of these I want to be enabled?
I think I have seen somewhere that the user of a GPS unit can use Profiles to select different kind of maps. (7) If that is correct how is this done?

I'm sorry - it is an awfull lot of questions. But I also find that the user manual for eTrex30 is very limitid and in fact not as usefull as I had expected. it is hard to find an answer to all the questions that comes to my nerdy mind  :)

Best Regards
Lars

« Last Edit: June 05, 2012, 06:42:57 AM by larshgf »

Seldom

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Re: How map-files are organized on eTrex30 and how they are selected?
« Reply #1 on: May 29, 2012, 03:12:47 PM »
Your question numbers:
1) All track points are recorded in UTC(Zulu) time.  Your Etrex uses the gmaptz.img to figure out your offset from Zulu and show a correct local time on your Etrex.  For more on this look here.
2,3,4) I generally accept this as an article of FAITH.  It works differently on older generation GPSrs like the 60CSX which can only have a single gmapsupp.img file.  There you can have a gmapsupp.img with multiple mapsets.  Each mapset has a unique FID.  With your Etrex, you'll likely be better off sending a single mapset at a time.  If you have downloaded MapInstall 4.0.1 (latest) it should handle the mapset renaming for you.  If you have an earlier version or are using MapSource, rename each gmapsupp.img after you send it, keeping the IMG extension.  Having done this you should be able to enable or disable individual mapsets. Sequence is Setup>Map>Select Map.
5) Splitting a gmapsupp.img can be used to alter files you don't have permission to change, so we don't discuss that here, but you shouldn't need to do this if you have downloaded maps that install in BaseCamp.  You can always send a new group of maps from BaseCamp.
6)  You can have more than one CustomMap file in the folder, and they will all show as a single map if CustomMaps is enabled.  If they overlay one another only one will show, and in order to disable the conflicting map you will need to rename the file from a computer.

larshgf

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Re: How map-files are organized on eTrex30 and how they are selected?
« Reply #2 on: May 29, 2012, 04:20:19 PM »
If the maps in the {CustomMaps} folder overlap there will be a kind of conflict? Will they both be shown?
If so I wonder if this problem could be solved by placing the two conflicting maps in a kind of {CustomMap} folder in the {Profiles} folder.? What I mean is that if each Profile on the GPS has a certain choice of settings - including maps disabled or enabled - then a change in profile might involve a change of maps?

Seldom

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Re: How map-files are organized on eTrex30 and how they are selected?
« Reply #3 on: May 29, 2012, 05:00:07 PM »
Essentially, there is only one CustomMap you can turn off or on.  I've got a geology map and a topo that overlay each other.  In order to see one, I need to rename the extension on the one I don't want to see to something like kmzzzzzzz.  If you can get that to work with profiles, I'm sure we'd like to know.

dbperry

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Re: How map-files are organized on eTrex30 and how they are selected?
« Reply #4 on: June 02, 2012, 02:33:01 PM »
If the maps in the {CustomMaps} folder overlap there will be a kind of conflict? Will they both be shown?

Yes, they are all shown, and this is where draw order becomes important. The KMZ with the higher draw order will show on top of the lower draw order KMZ, completely obscuring it. I have a number of examples in my collection of KMZ maps. See the explanation for "Bay Circuit "E to K" KMZ Series" in this map:
http://gpsfiledepot.com/maps/view/607/

For a simple example of one KMZ overlapping another, see these two maps:
http://gpsfiledepot.com/maps/view/578/
http://gpsfiledepot.com/maps/view/569/

But it is correct, all the KMZ files that are loaded on the GPSr are enabled or disabled as a group, and you can't individually select them on the GPSr.

Dave

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Re: How map-files are organized on eTrex30 and how they are selected?
« Reply #5 on: December 18, 2012, 09:28:42 PM »
An interesting adjunct to this discussion is that a file in the Garmin folder named simply gpsmapsupp.img does not appear in the map list in the etrex 30 map list. It appears to be enabled or disabled along with the buil-in global reputable base map. Other maps with names like gpsmapsupp-NZ.img do appear, and can enabled and disabled separately.

Cheers

SmugWimp

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Re: How map-files are organized on eTrex30 and how they are selected?
« Reply #6 on: December 19, 2012, 03:18:36 PM »
I work mostly with street maps, so my answers won't address the subject of overlays or anything of that nature.

1) I didn't know this. Thanks Seldom! :)

2) Garmin reads all of the binary img file, and separates the maps internally. Your garmin device is basically a computer appliance. I think it's some kind of Linux, but I never really dug in to find out. Think of the '*.img' file as kind of a 'folder' with different maps enclosed.

3) the Family ID (FID) is an identifier (typically) used in commercial maps. They have to be unique for each mapset. Most users don't need to worry about this info, unless they're creating commercial maps.  It will only pose an issue if you happen to find two maps with the same mapset.  This rarely happens, but when it does, something won't work.

4) With respect to 'street' maps, you typically only have one map for a particular region, so you usually turn them ALL on. With Topo and Overlays and such, I'll defer to the other folks' opinion, as I only recently got a handheld unit and you might already know more than I.

In any event, In 'Tools > Setup > Maps > Map Info' (depending on your model) is where you can turn on and off individual maps.

Just my $0.02

Cheers!

-- Smug
In a nutshell, I get claustrophobic.

Boyd

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Re: How map-files are organized on eTrex30 and how they are selected?
« Reply #7 on: December 19, 2012, 03:32:59 PM »
Really, if everything is as marco describes then it sounds like a bug in the eTrex firmware. Do you have another Garmin handheld (like an Oregon or GPSMap 62) that you can test the gmapsupp.img file on?

Seldom

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Re: How map-files are organized on eTrex30 and how they are selected?
« Reply #8 on: December 20, 2012, 09:19:31 AM »
An interesting adjunct to this discussion is that a file in the Garmin folder named simply gpsmapsupp.img does not appear in the map list in the etrex 30 map list.
Missed this on first reading, but marco hasn't got the correct spelling for "gmapsupp.img".  The question is should any file with an IMG extension appear as selectable?  But I guess Boyd noticed that.

Boyd

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Re: How map-files are organized on eTrex30 and how they are selected?
« Reply #9 on: December 20, 2012, 09:46:35 AM »
Haha you are giving me more credit than I deserve, I didn't notice the spelling. But on the newer devices (garmin calls them "N-map devices") it shouldn't matter because any .img file should be recognized.

But there were bugs related to map files reported in the early eTrex x0 firmware, which makes me suspicious - see Rich's review here: http://gpstracklog.com/2011/10/garmin-etrex-20-review.html

Quote
Rich Owings wrote:

A note about map management

Iím not sure whether this is a bug or not, but the eTrex handles maps differently than other recent Garmin models. When I loaded multiple maps, renaming them one at a time, they showed up in Map Setup as one combined mapset (shown at right).
UPDATE: It appears that this may not have been a Garmin issue. It is possible that a MyTrails update on October 30 fixed this issue. I can now upload individual mapsets, although I stil have a corrupted file that I canít get rid of!