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Fenix: Replacing the fenix basemap with a Trail network map

45878 Views 57 Replies 17 Participants Last post by  as4tik
I got so excited about the .img file installation proof-of-concept, I literally ran out to get the fenix at my local shop.
Umm, "Honey, about the credit card bill… remember all those times I saved $20 by changing my own oil?..."

After waiting what feels like a decade for useful ABCHR watch with GPS, now I have two!

I can't yet tell if the fenix & Ambit will be like my children and I'll keep both, or if they be like my other past watches and one of them will be on Craigslist in 6 months. I can tell it's going to come down to two factors

  1. How good is the fenix vs ambit tracks & sensor data in the real world of my hikes and jogs and vacation-wear?
  2. How good is the November Ambit update? I'm excited about that too.
  3. Is one of them better enough at one activity type or usage-model or the other to keep both?
(ok. 3 factors)

Anyway, back to the Trails "map" installation

************ WARNING: Do At Your Own Risk of turning your fenix into a paperweight ********************

  1. I copied the original gmapbmap.img from the fenix/Garmin folder to another folder on my PC for safe keeping.
  2. I used Garmin Map Install
  3. Selected the fenix.
  4. Message: "all my maps won't fit"
  5. So I chose just Washington and Oregon from Northwest Trails
  6. Installed it. Took about 2 minutes.
  7. It placed a second .img file in the Garmin directory of the fenix, called Northwest Trails.img
  8. I deleted the original gmapbmap.img
  9. I renamed the Northwest Trails.img to gmapbmap.img

The original basemap .img file is about 558kB.
The new .img file is 4590kB. (about 1/4th of the fenix capacity) and has essentially every known trail in a 500mile by 300mile 2-state area.

Way way more useful to me than the Garmin Basemap.

This is super helpful to a hiker… so I'll have not just my planned route in the fenix, I'll see all the other intersecting trails, and can identify their names. In the watch. It's that extra bit of back-up and confidence, yep, I've had paper maps blow away, and yep, I've had dead batteries in my handheld. Never at the same time though. :). Plus I can impress my friends with 1-inch 70x70 pixel black&white trail maps. Priceless.

Here are images:
Northwest Trails overview in Basecamp - it has a bajillion trails. Make a donation, it's worth supporting.

Northwest Trails zoom-in in Basecamp. What you'd typically use to map/overlay your Route Waypoints.
Text Map Line Organism

A place I've been: my existing Waypoints from Basecamp are in the fenix along with the NW Trails. (Key point = those are not GPS tracks, those are the network of trails from the .img file… aka the Background Map.

An arbitrary trail crossing seen in the map mode of the fenix. Note the crosshairs.

In the Orange menu you can "Select Pt"

And depending on what your crosshairs are pointing to… you get the underlying information (e.g. could be trail name, or POI details. In this case the Pacific Crest Trail.

(p.s. I like Demo Mode.)

And I did go for an hour run with both the fenix and ambit. Both on 1sec tracks. Verdict = No verdict yet.
  • The HR graphs are identical.
  • Tracks on map are very similar. No wildly phubar points. SportTacks-computed distances are within 0.01miles. Ambit "in-watch"/summary distance is 1% shorter. And the truth is out there somewhere.
  • The elevation graphs match. (baro-based I presume)
    • However the Ascent/Descent in Details seems quite (2x) wrong in the fenix… maybe GPS-based?
  • "In-watch" real-time Paces matched pretty close, by GPS standards: e.g. +/- 10 seconds.
    • Fenix Current Pace is not really instantaneous, it's doing some default smoothing I guess. It lags the Ambit by a few seconds when coming to an abrupt stop. Like the jump stop my basketball coach taught me in high school.
  • Can't review the HR and speed summary in the fenix. Huh?
  • Trending to give a slight nod to the Ambit for Training, for me. But also have no doubt that the fenix + Garmin Connect will be more than fine for the 97%.

Oh, and one more thing:
No fenix Automatic mode switching between Altimeter ("Variable") and Barometer ("Fixed")? If true that'll be a bummer.
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or_watching, you are a grate man! your experiment is a first in the world with a map of Garmin fenix. And thank you for your experience.
Great finding. It works very well. I have a question though: my maps from Garmin are pretty heavy in details, and the Fenix has a hard time to zoom in and out. Mapsource has the possibility to show a different level of details. Is there a way to save the maps or generate the .img with more or less level of detail?
Thanks in advance
My Fenix has a hard time to zoom in and out to. It seems normal with map. But to chose different level of details you must change map in Base Camp. Not level but map. Decreasing detail of map impossible on the watch. I use the maps from the server In our country not too many detail it seems.

Support of maps didn't promised and didn't announced. I guess we should say thanks to Garmin for the fact that we're able to download the map in to the watch.
I don't understand, is it possible to have different level of information when zooming out / in with a custom map on the watch ? For example, I would like to have a general map when zooming out and have a detailled map when zooming in.

How to select the area on the map and its level of detail we want to put into the watch ?
Yes, it is possible to have different level of information when zooming out / in with a custom map on the watch. That is true now. But to choose the level, when a detailed map begins to appear, as in hiking device (like on Montana, Oregon, Dakota, eTrex) - imposible.

How to select the area on the map and its level of detail we want to put into the watch ?
Unfortunately, we can not to select level of detail, which should appear into the watch.
The problem with recent maps, Garmin, local topo, OSM, velomaps... is that they contain a lot of additional information on top of the mapping information that makes then very big, too big to fit into the small memory of the Fenix, that's why old maps from a time when devices had little built in memory are nice for the Fenix. The problem with these old maps is that the mapping information is obsolete.

For the Fenix, the best would be to have some stripped down maps with only the basic mapping information.
For this reason, useful maps OSM. They are fresh, the most accurate and part divided into 5 MB, which is convenient for loading into Fenix
Convert map in to img format is very difficult. There are no simple way for this.

without purchasing Garmin MAPS you may use maps from
Hi As4tik,

I was on openstreetmap. I saw that we can export map in xml. What is the format to choose ? When i Will have the export file, what i have to do ? (Where to put the file). Can the Fenix use other maps than img maps ?
You do not need to use the export to their main website. Maps directly from there can not be picked up for Fenix.
But you can use a different server, which is able to convert maps from OSM to "img"-format for Fenix.
For example here is the server: Free worldwide Garmin maps from OpenStreetMap

Choose no more than one sector. Then the map will not much about 5MB. After converting the wait for you will receive an email with a choice that can be used. From there you have to download "" This is your map in the format of "img" to easily copy the memory Fenix.
I may be mistaken, but it seems other names will not be seen.

Remove the original basemap is not necessary.
You are welcome!
For me it is the most useful source too.
We don't have the same maps for Ukraine too :(
I haven't really noticed any battery drain with a 3meg file, but I have noticed my Fenix seems to operate a bit slower. As for turning off Maps I haven't seen a setting anywhere.
There are no Settings. Since the maps is not officially supported.
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