Custom raster maps for CO, OR & DK series

[Coggins]

http://garmin.blogs.com/softwareupdates/2009/10/index.html

* Added support for Garmin Custom Maps. See our blog post about this new feature at
http://garmin.blogs.com/softwareupdates/trail-tech/.
* Report problems with this beta to TrailTech@garmin.com

[Boyd]

What a surprise; I knew somebody would eventually give us a tool for this, but never imagined it would come directly from Garmin. Sounds very cool, will be trying it with my Oregon when I find the time. I'm hoping there's a better workflow using GlobalMapper to export the image and KML, so I can use some of the vast amount of raster imagery I've already got. Would be a pain to have to georeference everything with Google Earth. Nevertheless, I think this is pretty exciting news! 

Here's one more reason to think seriously about Garmin's new models as opposed to the old eTrex and GPSMap series which do NOT support this feature.

http://garmin.blogs.com/softwareupdates/2009/10/index.html

Despite the growing breadth of maps designed specifically for outdoor handhelds, sometimes the best map for a specific activity is only available in printed form or as a PDF or JPG file.  Running the latest beta software releases for Garmin Colorado, Oregon, and Dakota devices, using paper maps with Garmin outdoor handhelds is easier than ever with Garmin Custom Maps.  This unique feature allows users to combine Garmin map drawing technology with georeferenced map images, effectively putting a paper map inside your Garmin GPS.  Creating a Garmin Custom Map for your Colorado, Oregon, or Dakota device is easy with the following steps.

[maps4gps]

That sure decreases the need to spend 100's - 1000's of hours creating custom vector maps.

Download the 1m DOQQs imagery and overlay CN for street names and routing.  Plus a few specialized overlay mapsets. 

[alpine]

Kind of tantalizing kinda. But I can't use any of those models. The screens to small.

Maybe a preview of things to come, but somehow I doubt it.

[Boyd]

So it looks like we can export a .kmz file directly from Globalmapper (see: http://www.globalmapper.com/helpv11/Help_MenuBarAndToolBar.html#file_menu_export_kml_raster), create a \Garmin\CustomMaps folder on the GPS (or a card), drop the .kmz file into it and head out to the woods.

That is amazing - I have almost 200GB of source raster imagery (USGS quads and 1 foot/pixel aerials) in Global mapper already. I wonder what the limit is on file size? It sounds like the unit itself figures out when to display these images and you don't need to manually enable them.

Anxious to give it a try!

[Boyd]

Kind of tantalizing kinda. But I can't use any of those models. The screens to small.

What are you using now? The Oregon screen is actually larger than the 60csx...

[Boyd]

Here are a couple examples. The good news: it was very quick and easy to make the maps in Globalmapper using the method I proposed above. They look great on my Oregon 400t.



The bad news: it is really S L O W to draw these maps on the screen and I ran into some bugginess. The further I zoomed in, the slower the screen update until the 500 foot level where the map never drew. It then disappeared no matter what zoom level I used and I had to reboot the Oregon to get the raster image back. Went though this same sequence several times.

There are also some pretty significant limits as to how big a map you can use. See the info in Garmin's forum here: https://forums.garmin.com/showthread.php?t=2646

Images over 1 mega pixel (1024x1024 pixels, 512x2048 pixels, etc.) will be rendered at a reduced resolution on the unit. If this is causing a problem for your map, you can split the image and use multiple jpegs inside of one kmz file.

The max number of Custom Map jpegs you can load is 100.

Garmin really deserves kudo's for making this available to us. Even more brilliant, it's multi-platform and should work fine on the Mac as well as Windows using Google Earth. They have really beat everyone else to the punch here and just made it extremely easy for anybody to make their own maps without buying any special software.

But in its present form, it doesn't look too useful to me yet. It's very slow and buggy and even using small tiles, you can't map a very large area this way. OziExplorer CE is infinitely more powerful running on a Win CE device (like the Magellan Triton, for example). It zooms and scrolls quickly. And using their MapMerge utility you can make huge raster maps (I have one that is about 400MB for example).

So it *is* possible to get good performance from a handheld with raster images. Hopefully Garmin will sort all this out in future updates though... this is still beta software. Not bad for a first effort.  

[Boyd]

Here's another example of the same area, using New Jersey's excellent 1 foot per pixel 2007 digital orthphotography. This time I chose a smaller area resulting in about a 1MB file (the USGS example above was about a 4MB file). This littler file is more responsive and I am able to zoom in much farther.

[Boyd]

It is very good. But Globalmapper reports 1 ft/pixel as does the metadata: https://njgin.state.nj.us/NJ_NJGINExplorer/ShowMetadata.jsp?docId={DC1F4E29-28A5-11DB-9EFE-0003BA2C919E}

Abstract:  Digital orthophotography of New Jersey in State Plane Coordinate System NAD83 Coordinates, U.S. Survey Feet. Multi-spectral digital orthophotography was produced at a scale of 1:2400 (1"=200') with a 1 foot pixel resolution for The State of New Jersey totaling approximately 8,162 square miles.

[-Oz-]

This is really really cool.  I think I'll actually have to get a Garmin Dakota now.  I have some great imagery right now (like 10cm images).  Its just not for somewhere I'd be vacationing at.

[Boyd]

As I said above, it is really cool and Garmin deserves a lot of credit. But it's still very beta. Sluggish performance and some bugs which forced me to restart the GPS to clear them. It will draw any other map which is enabled on top of your raster image. This might be good or bad, depending on what you want. I turned off all of the vector maps, but sometimes it would still draw the pre-installed US Topo vector maps on top of my raster image anyway.

It would only let me zoom in to about 800 ft with the USGS map in the example I posted. When I zoomed farther, the raster image went away and did not reappear when I zoomed back out. I had to restart, then it worked. This was a reproducable bug. Am going to play with this a bit more today and actually go out for a walk, which I haven't tried yet.

So I think it offers tremendous promise, but it still needs a lot of work. Before you run out and buy a new model for this feature, you might want to wait until the software is out of beta to see how well it works. Of course, there are other reasons to get the new touchscreen models - I like my Oregon much more than my 60csx all around. The new ability to name mapsets anything you like and drop them in the Garmin folder is another big advantage to these models.

[IndyJpr]

It will draw any other map which is enabled on top of your raster image. This might be good or bad, depending on what you want. I turned off all of the vector maps, but sometimes it would still draw the pre-installed US Topo vector maps on top of my raster image anyway.

There is a Draw Order attribute (within the kml file) that is supposed to control this - any value equal to or above 50 should keep the raster on top of other maps.

This link has more info:
https://forums.garmin.com/showthread.php?t=2646

[Boyd]

Got out for awhile this afternoon and test drove a pretty large custom map from NJGIN 2007 Digital Orthophotography at 1 foot/pixel. I used Globalmapper to export a gridded .kmz file with about 80 1024x1024 tiles (this is getting close to the limit of 100 tiles). The mental math in round numbers is pretty easy: with 1 ft/pixel imagery and 1024x1024 tiles, a mile is about 5 tiles. 10 tiles would be about 2 miles. 10x10=100 tiles, which is the limit for custom maps. So you can only have an area 2 miles x 2 miles (4 square miles) at this resolution.

The Oregon pegged me within a few feet of my location on this 4 foot wide bridge.




Google's imagery on the iPhone (from the USDA in this case) is nowhere near as good as my custom map  



Playing with this on my own land earlier in the day I encountered a number of bugs. If you zoom in too far and try to pan the map, it will crash (backlight goes out but screen shows a messed up image until you reboot. This happened repeatably at 20 and 30 foot zoom level, and less frequently at 50 foot zoom. It scrolls very smoothly as you walk, and even while driving at slow speed. No crashes when zooming way in while walking unless I try to manually drag the screen.

Tracking seems to be totally messed up. When set to display track it always shows a straight line from the beginning to your current position. I saved this track and then displayed and it looked the same - a straight line. Tried importing the track in mapsource and it only contained a few points which were all on top of each other. Maybe I am missing something, but I never saw this happen before.

Nevertheless, it's beta so you have to take the good along with the bad. Overall I was impressed by how well it worked in the field. When the bugs get squashed this will be really amazing.

[-Oz-]

haha, yea if only that was the case.

Regarding custom maps: It has a lot of potential considering its still in beta. I was debating getting a touch screen anyway so this might push me over the top.

[Coggins]

OK, back on track. As image resolution gets mentioned frequently, it's important to note that it is measured by all of the following, not only the pixel count:

Spatial Resolution, Temporal Resolution and Spectral Resolution.

For a primer, see the following page with examples:
http://www.satimagingcorp.com/characterization-of-satellite-remote-sensing-systems.html

Also one has to take into account the % rating for weather/smoke cover from when the photo mission was flown, as well as the local time for shadow masking. Georeferencing obliques requires forward azimuths, range to target, and image distortions will have to be taken into account. As this isn't for the focus of this topic, I'll leave that for another day.