What does Moagu do?

Moagu converts a georeferenced map image into a bitmap format  for use in a compatible Garmin handheld GPS units: the GPSMapper series (60C(S)x, 76C(S)x, and Astro), and some models in the eTrex line. For more recent Garmin GPS receivers, like Colorado/Oregon/Dakota/62/78 series handheld GPS units, you can create high-quality Custom Map overlays from map and aerial imagery using my freemium program G-Raster. But Custom Maps are limited to a maximum of 100 image tiles, each covering a megapixel in size; using Moagu’s BMap2MP utility, you can convert USGS topographic maps, and other graphical maps, into a format that these newer units can use without the size limitations of Custom Maps.

But Garmin units use vector graphics for the display – isn’t this impossible?

For older units, that was thought to be true; Moagu gets around this limitation by converting the imagery into a vector-friendly format. Newer Garmin models have raster support built-in, but for your imagery, you’re limited to a maximum of 100 one-megapixel tiles. The G-Raster program can automatically chop up a larger image into smaller tiles to conform to this limit.

What kind of maps can Moagu create?

Two kinds. Standard Moagu maps are a virtual “bitmap” clone of the original image; these only work on older Garmin GPS units. Moagu also now comes with a GUI front-end for the free command-line utility BMap2MP, which can “vectorize” a raster bitmap image for use in many Garmin units, including both older and newer models

How are Moagu maps better than standard vector maps?

They’re not; they’re different. Vector maps are smaller in size, searchable, and display far more quickly than Moagu maps. If there’s a vector map for your area of interest that includes all the details you need, you should definitely use it. But bitmaps have advantages as well:

  • Vector maps don’t cover the entire world, and don’t always have the information you need; if you can convert a paper map to digital format and georeference it to geographic/WGS84 coordinates, you can use it with Moagu.
  • There are tools that can create Garmin vector maps, but they typically requires some level of technical expertise to use;  Moagu can be easier to use. In particular, converting a USGS topo map using Moagu or BMap2MP is a snap – download the image file from a website, convert it to geographic/WGS84 using Moagu’s built-in reprojection utility, then push a few buttons. Tutorials walk you through every step.
  • Vector maps have a limited number of standard symbols; creating custom symbols is not a straightforward task. Moagu/BMap2MP converts bitmap images directly, preserving all their symbology and typefaces intact.
  • Vector maps are designed for speed and efficiency; bitmap maps are more often designed with human use in mind, and can be easier to read. Many people are more comfortable using USGS topographic maps rather than their vector equivalents on a Garmin; Moagu makes it easy to view and use a standard USGS topo map image on a Garmin handheld GPS.

Which are better – standard Moagu maps or those created with the BMap2MP utility?

Each type has advantages and disadvantages, depending on what kind of bitmap image you’re trying to use with your Garmin.

  • For bitmaps with lots of detail, like aerial photographs, Moagu maps are superior; they can display 254 colors vs. 62 for BMap2MP maps, with better detail, and at comparable draw speeds.
  • For graphic maps with large solid areas of color and clearly-defined widely-spaced lines, BMap2MP can produce maps that draw much faster than Moagu maps.
  • For graphic maps with lots of fine details, it can be a toss-up; Moagu can usually reproduce the fine detail better than BMap2MP, but at some cost in display draw speed.
  • For newer Garmin units in the Colorado/Oregon/Dakota/62.78 series, you have no choice; only maps created with BMap2MP will work with these units.

You can always try creating maps with both techniques, and seeing which one you prefer.

How about USGS topographic maps?

I’ve spent a lot of time optimizing both Moagu and the BMap2MP utility to maximize the quality of USGS topo maps creating by both techniques. BMap2MP maps can have issues with areas that have lots of detail, like topographic contours spaced closely together, while Moagu usually does a good job of reproducing those. But BMap2MP maps have draw speeds on the GPS unit about 2-3 times faster than Moagu maps. In the field, I usually find the draw speed of BMap2MP maps outweighs the slightly better detail of Moagu maps, since I’m usually using the GPS to figure out where I am on an actual paper topographic map.

Do you have sample maps available?

Yes; below are links to downloadable installers for the Humphreys Peak topographic map in Arizona, created using both Moagu and the BMap2MP utility. These will install the program for use in either Garmin’s MapSource program, or Garmin’s newer free BaseCamp program. Either program will let you view the maps, and upload them to compatible Garmin GPS units. Also included is a GPX waypoint file to help you zoom in on the area covered by this map.

Humphreys Topo Map – Moagu installer

Humphreys Topo Map – BMap2MP installer

Note: For both maps, you’ll have to zoom in fairly close to see any detail in MapSource or BaseCamp, at least the 0.3-mile zoom level; set the detail level to Higher for better results. On your GPS unit, the maps will typically only show up at the 500-ft. or 800-ft. zoom level (metric equivalents are 120-m or 200-m zoom level).

You can also download sample Moagu and BMap2MP maps from the GPS File Depot site:

Nantucket marine chart (BMap2MP)

Coyote Buttes topo map (Moagu)

What are the limitations on Moagu maps?

There’s a bunch – there’s a section in the help file that lists them all. Initial display speed is probably the biggest issue, but once a Moagu map is displayed, it will keep up with your current position at walking speeds, and for some maps (like USGS topo maps), even at bicycling or slow driving speeds. See this review at GPS Tracklog for actual results with mountain biking, and you’ll see that Moagu maps are definitely field-friendly. So don’t judge it by the initial display speed – take it out for a walk, or a bike ride, and see how well the display updates your position. Maps created by the BMap2MP utility are much faster in display and updating, but have fewer colors than Moagu maps (62 vs. 254), and may have other level display issues.

Is there a size limitation?

I’ve processed one large USGS topo map in Moagu that measures about 10,000 pixels square, or the area of about 5-6 standard 7.5′ USGS topo quads, without serious issues. Took a while, though, and I’d recommend starting with smaller areas. Large images are broken down into smaller tiles, to maximize display speed. BMaP2MP vector maps are also limited to roughly 10,000 x 10,000 pixel sizes, but for best results with these, you should use an image no larger than a standard USGS topo map (0.125 degrees by 0.125 degrees); see the help file for more info on this.

Where can I get USGS topo maps for use with Moagu?

Maps area available from the LibreMap site, and many state/federal government websites; check the helpfile for more info. The BMap2MP tutorial in the helpfile also offers links to several sources for individual USGS topo maps by name.

Where can I get other raster map imagery to use with Moagu?

Many US states have data sites that offer downloads of georeferenced map imagery; do a Google Search for your state’s name and “GIS” to start. Beyond that, a Google Search will reveal hundreds of sites with downloadable map imagery.

Can I install Moagu/BMap2MP maps into Garmin’s MapSource or BaseCamp programs?

Yes; the help file gives step-by-step directions on how to install and view Moagu/BMap2MP maps in MapSource or BaseCamp. Using this, you can upload both regular Garmin vector maps and Moagu/BMap2MP maps into your Garmin unit.

What other kind of map images can Moagu convert to Garmin maps?

Any georeferenced image, or one that can be georeferenced, that can be re-projected to geographic/WGS84 coordinates can be used; the help file describes the process, and offers free solutions that help put your map in the right format. Examples of this kind of imagery include aerial/satellite photography, standard road maps, geology maps, road grids, scanned maps … If you can georeference it, you can make a Moagu map out of it.

Can you display other information with Moagu/Bmap2MP maps?

Yes, waypoints, tracks and custom POIs display normally on top of a Moagu map. If you create a custom vector .img file with transparency, it will display on top of the Moagu map as well; see the center image on the home page for an example of that.

How hard is it to make a map?

I’m not going to say that it’s trivially easy; you will need to read the help file to learn some of the basics. But I’d like to think I’ve made it a simple, step-by-step process; see this review at the GPS Tracklog for their opinion. And I’ve included  tutorials that walk you through creating your first USGS topo map, both with the regular Moagu program and the BMap2MP utility. If you run into problems that the help file can’t resolve, please let me know.

Is there a demo version?

Yes, the program installs in a demo version. For Moagu maps, you’re restricted to a single tile at all the zoom levels, and each of those tiles gets a red border on the outside. For BMap2MP vector maps, you’re restricted to an area covering 1000 x 1000 pixels of your map graphic; for a USGS topo map, this is about 2 square miles in area. Purchase/registration, which can be done directly from the program, removes these restrictions.


$9.95; use the “Buy The Program” option on the main menu to purchase and register the program via credit card.


Free for all registered purchasers; just use the latest installation program, or in some cases the special updater..

What’s your relationship with Garmin?

None at all; neither I nor Moagu have any direct connection with Garmin (a trademark of Garmin Ltd).

I have another question …

Download and install the program, then look through the help file – hopefully you’ll find the answer to all your questions there. If not, drop me a line.

Any other suggestions?

Download the program, run through the tutorial, and create your own map with the demo version. You’ll see that the program works as advertised. Is it perfect? No, but it’s better than the alternative, which is no bitmap Garmin maps at all for older units. Newer models in the Garmin Colorado/Oregon/Dakota/62/78 series can display bitmap images using Custom Map overlays (see my other program G-Raster for more info on this), but even for these units, creating topographic maps with the BMap2MP utility can get around the map size restrictions that Garmin has specified.