Custom raster maps on newer Garmin GPS's

Alun

Here's an interesting post for anyone who has a newer Garmin GPS such as the Colorado, Oregon or Dakota ...

http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=130392

Furthermore, if you already have maps georeferenced in OziExplorer you can save yourself all the bother of georeferencing them through Google Earth ...

http://www.gpspassion.com/forumsen/topic.asp?TOPIC_ID=130525

Almost makes me want to go out and buy a new GPS

P.S. Is there anyone on here who has one of the above GPS's who'd be willing to meet up (Bray, S. Dublin) and help me try this out to see if it works as well as it's claimed? I've already made a suitable map for testing purposes. PM me if you're interested.

Takeshi_Kovacs

hmmm, yes i have been toying with the idea of upgrading from 76csx, but when i run a comparison of 76csx against newer models, i didn't see any real need to upgrade. But with being able to put your own map on gps now, well, it does sound good and enticing.
I assume that satellite pictures can be used as an overlay in the new gps now as well?

Alun

Takeshi_Kovacs wrote: »

I assume that satellite pictures can be used as an overlay in the new gps now as well?

Basically, if you can georeference it you can use it, although there are, of course, legal / copyright issues with using, say, GoogleEarth/Maps imagery.

Also note that currently this requires first installing beta software, and there are some reports of units crashing when panning/zooming when zoomed in close, as well as some not very obvious limitations on file sizes / dimensions, but I'm sure it'll all get sorted out in due time.

IrlJidel

The custom maps feature is now available as a production release.

http://www.gpsfix.net/garmin-custom-maps-official/

You have to go through a few hoops to reference your maps though.
The aerial imagery in GoogleEarth for Ireland is
a) only available in lowres for most mounainous areas
b) where available in hires it is not georeferenced correctly in many places.

So you'll usually have to use OziExplorer. You have to go through a few steps to create an OziExplorer map in a format and projection suitable for OziMapToKMZ

1) Map referenced in OziExplorer should only have 4 reference points
2) If you are using an Irish scanned map the projection is wrong for OziMapToKMZ so you have to use the OziExplorer addon Mapmerge to change the projection to Mercator. Mapmerge creates a map in ozf3 image format.
3) OziMapToKMZ requires the map in JPG, PNG or BMP format. So you have to convert the ozf3 created by Mapmerge to a a supported image type.
4) However, OziExplorer wont extract the images from maps created by MapMerge. You need to use ozf2img (same author as OziMapToKMZ) or DeMapper tools to create the png image file. I used ozf2img but I believe DeMapper is better as it doesn't create an extra white border around the map image.
5) Finally run OziMapToKMZ

You can still use Google Earth but instead of using google imagery to reference you can grab a kml that will show openstreetmap,yahoo,bing maps layers in GE and use them to reference. Openstreetmap has fairly accurate summits that were imported from Mountainviews which could be useful reference points.

http://www.mgmaps.com/kml/

Alun

IrlJidel, have you actually tried this out yourself yet? I gave the whole procedure using OziExplorer a bash to generate an overlay file and loaded that into Google Earth which worked quite well. The registration with the map overlay wasn't perfect, but then, as you mentioned, the georeferencing of Google Earth's satellite imagery doesn't seem to be spot on either according to many sources. I don't have a suitable GPS, but if the results from this are good enough, I just might be tempted to ask Santa for an upgrade of some sort

IrlJidel

Alun wrote: »

IrlJidel, have you actually tried this out yourself yet? I gave the whole procedure using OziExplorer a bash to generate an overlay file and loaded that into Google Earth which worked quite well. The registration with the map overlay wasn't perfect, but then, as you mentioned, the georeferencing of Google Earth's satellite imagery doesn't seem to be spot on either according to many sources. I don't have a suitable GPS, but if the results from this are good enough, I just might be tempted to ask Santa for an upgrade of some sort

I've tried it out and loaded it onto my GPS. Haven't used it in the field though.

The map kicks in at 1.2km zoom, but is only really readable at 500m zoom levels. My overlay only seems a few meters out.
The level it displays at appears to be related to meters/pixel. My original map was at 3m per pixel.

If you dont change the projection then the map will be out 200->500m in places.
The road data layer is correct in GE so use that to check if your map is correct or use the OSM overlay.

If you are a very good boy this XMAS ask Santa for an Oregon( 240 x 400 pixels) rather than a Dakota (160 x 240 pixels) as it has higher resolution

Takeshi_Kovacs

My poor poor 76csx...
Hmmm might have to send a list to santa as well..
How big a map segment can you upload to say 2gb card using this new rastermap ?

Alun

Here's another option ...

http://freegeographytools.com/2009/create-garmin-compatible-raster-kmz-files-from-georeferenced-imagery-with-g-raster

Also a Garmin developers forum with some handy stuff too ...

https://forums.garmin.com/forumdisplay.php?f=205

Takeshi_Kovacs

I am tempted to to buy the oregon 550, but i just dont know if the accuracy matches up to 76csx (especially under cover). The ability to add custom maps is a big plus for me though, although i care less for the included camera.
If Garmin were to bring out an Oregon 550 without the camera, and same antenna as 76csx, then that would be really sweet.

Alun

Yes, I've been reading some things on various fora expressing concerns about the Oregon series, or more accurately the Cartesio chipset, under tree cover. There's nothing very concrete though.

My Vista HCx is great in this regard (and that has the same type of antenna) .. you'd almost have to bury the thing six feet under to get it to lose lock, and I wouldn't want to go backwards in that regard. That having been said, it took a while for Garmin to get to grips with the MTK chipset in the new H etrex series, with all kinds of problems in the beginning, but after quite a few s/w and GPS firmware updates they eventually got it sorted.

The 550t is supposed to be better than the 400t in the screen dept. and is supposed to be more legible but I'm not sure I want to spend that sort of money really.

IrlJidel

Alun wrote: »

The 550t is supposed to be better than the 400t in the screen dept. and is supposed to be more legible but I'm not sure I want to spend that sort of money really.

The difference between the x50 and x00 series are:

x50 supports USB2 for faster transfers
x50 has a 3D axis compass
x50 has improved screen readiblity
x50 store more waypoint and routes ( 2000 vs 1000 & 200 vs 100)
x50 has a geotagging camera.

There are rumours of a 450 series which would be the same as the 550 but without a camera.

Alun

IrlJidel wrote: »

There are rumours of a 450 series which would be the same as the 550 but without a camera.

Now that would be interesting ... I was on the verge of ordering a 550t, but I might wait a bit now.

IrlJidel

IrlJidel wrote: »

x50 supports USB2 for faster transfers
x50 has a 3D axis compass
x50 has improved screen readiblity
x50 store more waypoint and routes ( 2000 vs 1000 & 200 vs 100)
x50 has a geotagging camera.

At the risk of sounding vulgar, price bracket?

IrlJidel

Deleted User wrote: »

At the risk of sounding vulgar, price bracket?

I got mine through directwebretail:

http://www.directwebretail.com/Outdoor-GPS/

My guess is that the 450 will be priced the same as the 400 is currently.

That been said, I would guess that you will see price drops on the x00 series when the 450 is released.

Alun

Well, I've caved in and ordered a 550t

Takeshi_Kovacs

Heh couldn't resist could ya !!:P
I was very close to ordering one too, but i think i will hang tough and see if this 450 comes out.
Who did you order from by the way?

Alun

Takeshi_Kovacs wrote: »

Heh couldn't resist could ya !!:P
I was very close to ordering one too, but i think i will hang tough and see if this 450 comes out.
Who did you order from by the way?

Yeah, I'm such a gadget whore I got it from Amazon in the end.

Alun

Well, it arrived today, and I'm reasonably impressed so far. The custom maps I put on it look fantastic, the only thing that I need to think about is where exactly to crop the maps to avoid any white borders when converting from Ireland1965 to Mercator projection.

At first sight it doesn't appear to be as sensitive as my Vista HCx, and I still have to get used to the interface (lots of key presses needed in some cases compared to the Vista, involving continually going back to the main menu, i.e. no 'context' menus). I also bought a hard case for it, which I think was a mistake. It's huuuuge, and a bit unwieldy. More to come as I get used to it, and use it for the first time 'in the wild' at the weekend.

IrlJidel

Alun wrote: »

Well, it arrived today, and I'm reasonably impressed so far. The custom maps I put on it look fantastic, the only thing that I need to think about is where exactly to crop the maps to avoid any white borders when converting from Ireland1965 to Mercator projection.

Do your cropping after you do the conversion. I'm pretty happy with the results. I made mine with DrawOrder 49 so that roads and tracks from my vector maps appear over my custom map. Roads and paths from my vector maps align very well.

Alun

IrlJidel wrote: »

Do your cropping after you do the conversion. I'm pretty happy with the results.

I'm not sure I understand how that would work.

I have an Ozi map which I've converted to WGS84 in it's entirety using Ozi MapMerge (it was a bit too fiddly and imprecise to do the cropping in MapMerge). Now, when I calibrated the maps I also added corner marks at the edge of the map area proper, and MapMerge seems to have honoured these and cropped off the border which is nice. But due to the rotation it created a white bounding box to contain the rotated map.

When using OziMapToKmz, I'd have to keep the entire map image otherwise the info in the .map file would be invalid, and after conversion I'm left with several small .jpg's (all under the 1 megapixel/3MB limit) in the .kmz file, so I can't crop then either.

I made mine with DrawOrder 49 so that roads and mappoints from my vector maps appear over my custom map. Roads and paths from my vector maps align very well.

I did wonder about that, but decided against it. I'll be using it primarily for outdoor use, and if I want to use the underlying maps I can use a different profile (I think, I haven't explored that option very much so far).

IrlJidel

Alun wrote: »

I'm not sure I understand how that would work.
I have an Ozi map which I've converted to WGS84 in it's entirety using Ozi MapMerge (it was a bit too fiddly and imprecise to do the cropping in MapMerge). Now, when I calibrated the maps I also added corner marks at the edge of the map area proper, and MapMerge seems to have honoured these and cropped off the border which is nice. But due to the rotation it created a white bounding box to contain the rotated map.

I used MapMerge to do the cropping.

If you want to do it precisely it is awkward you would have to
1) Use Mapmerge to do the projection conversion
2) Extract image from ozfx3 to png using Demapper
3) Crop this new image using your favorite image software
4) Recalibrate cropped image in Ozi

Bit of a pain.


Would using MAPC2MAPC reduce any of the steps?

Alun

IrlJidel wrote: »

I used MapMerge to do the cropping.

If you want to do it precisely it is awkward you would have to
1) Use Mapmerge to do the projection conversion
2) Extract image from ozfx3 to png useing Demapper
3) Crop this new image using your favorite image software
4) Recalibrate cropped image in Ozi

Bit of a pain.

Yes, that would probably work, although I'm not sure about how to enter the calibration points when doing the recalibration in that case. Could I still enter them in Irish Grid, even though I'm calibrating a map in WGS84 / Mercator? I'll give it a try.

I wanted to maximize the useful area of the map I was calibrating, especially on the extreme southwestern edge, and the thumbnail image in MapMerge was a bit too fuzzy to see the necessary detail.

As an aside, it'd help if there was some way of defining an RGB value to be used for transparency somehow, which would help in getting rid of some other areas of the printed map that I didn't want to see (tried Googling it but to no avail).

Would using MAPC2MAPC reduce any of the steps?

I don't know, I haven't spent a lot of time with it yet.

jolly47roger

Yes, MAPC2MAPC will simplify it. Open a .map calibration file (it will find the image); select Edit>Crop Map and save;Left click for the top left corner of the crop area, right click for the bottom right. (Click as many times as you need - it doesn't drag). Then File>Write Calibrations. This writes the cropped map and a matching calibration so no need to re-calibrate. Then open the calibration you have just written then File>Write Garmin Custom Map. The first time you run it use Edit>Preferences to set the tile size (usually 1024).

Takes less than 2 mins per map. The map needn't be orientated North-South.

Alun

As it happens I've been playing with MAPC2MAPC today and there seems to be a problem somewhere. I created a kmz file OK, but when overlaid onto Google Earth satellite imagery I immediately noticed that certain features such as lakes and roads were way off. The kmz file I made using the other method described above was a very small amount off in places, but given the bad registration of Google Earth images in some places that wasn't surprising.

So to test things I loaded the .map file generated by MAPC2MAPC into OziExplorer, loaded up my standard waypoints (summits, car parks etc.) and they were also off by quite a bit too, by different amounts and directions in different areas of the map as well. The same thing happens if I rescale the map by, say, 50% as well.

jolly47roger

I'm puzzled by that as all my other images have been spot on - I'm the author, by the way.

On oddity with Google Earth is that it will stretch a map over hills and valleys if Terrain is checked.

Please send me your calibration file (.map) and image and I will fix it.

Send to john (at) the-thorns.org.uk

IrlJidel

jolly47roger wrote: »

Yes, MAPC2MAPC will simplify it. Open a .map calibration file (it will find the image); select Edit>Crop Map and save;Left click for the top left corner of the crop area, right click for the bottom right. (Click as many times as you need - it doesn't drag). Then File>Write Calibrations. This writes the cropped map and a matching calibration so no need to re-calibrate. Then open the calibration you have just written then File>Write Garmin Custom Map. The first time you run it use Edit>Preferences to set the tile size (usually 1024).

Takes less than 2 mins per map. The map needn't be orientated North-South.

I was playing with MAPC2MAPC and made a garmin custom map using an Irish Map I have calibrated in Oziexplorer.

However, when I viewed the custom map in GoogleEarth it didn't align perfectly.

Am I correct in saying that GE and Garmin need the maps using Mercator projection?

Does/will MAPC2MAPC support changing the projection?

jolly47roger

You are correct, GE needs Mercator; Garmin I'm not sure. For walking scale maps it makes little or no difference.

If you only have 2 calibration points, try checking 'Stretch not rotate' on the Edit>Preferencs page. If that doesn't help, send me the files as above.

Alun

I think however that converting to Mercator is important in this instance. When I convert an Ozi map to Mercator / WGS84 using Ozi MapMerge, the generated image is rotated by approx 1.3 degrees clockwise. Possibly the difference between Mercator and British Grid is insignificant for OSGB maps, I don't know, but it certainly seems to be so for Irish grid maps. If MAPC2MAPC can't do the reprojection as well changing the datum then it would seem it's not suitable for our purposes.

For completeness, I can confirm I have Terrain turned off in GE. I have also tried adding another two calibration points, to no avail.

I'm busy uploading a bunch of stuff for you now, and will mail you the link when it's ready.

IrlJidel

Alun wrote: »

I think however that converting to Mercator is important in this instance. When I convert an Ozi map to Mercator / WGS84 using Ozi MapMerge, the generated image is rotated by approx 1.3 degrees clockwise. Possibly the difference between Mercator and British Grid is insignificant for OSGB maps, I don't know, but it certainly seems to be so for Irish grid maps. If MAPC2MAPC can't do the reprojection as well changing the datum then it would seem it's not suitable for our purposes.

I suspect it works without reprojection in Britain as it is near to the central meridian where rotation is 0.

You can see the divergerence by looking at the map displayed http://www.movable-type.co.uk/scripts/latlong-gridref.html

It might be possible to fudge a closer match to Mercator if we set rotation for each tile in kml - Have a look at this post:
http://bbs.keyhole.com/ubb/ubbthreads.php?ubb=showflat&Number=658771#Post658771

MAPC2MAPC should still be very useful as it is easier using MAPC2MAPC to crop the Mercator image produced by Mapmerge

Alun

@IrlJidel ... Well, I've just had more contact with John and sent him some sample files. He replied that he could see no problem with the overlay he generated so I started all over again and this time it worked for some reason. It's important that you do everything in the right order, i.e. Load the original calibration file (e.g. xxx.map), then save it , i.e. 'File > Write calibrations', then load the modified calibration file (e.g. xxxwgs84.map) and then generate the kmz overlay. If you're cropping the map before generating the kmz, then crop it and then reload the newly generated .map file (e.g. xxx_cr.map) first before doing so.

There is however a small, and variable over the map's area, discrepancy between the two overlays. Which is 'better' is debatable at the moment.

I suspect it's due to what you mention in your post, i.e. that a simple rotation of a complete map covering any significant area isn't going to be correct over the entire area, and that either a proper deformation or as a compromise, individual rotation of each individual tile may be the answer.

EDIT: I note by looking in the doc.kml file that mapc2mapc indeed applies a rotation (although each tiles rotation is the same) to each tile, and not as Ozi MapMerge does, rotate the entire map image and then generate the tiles with no rotation.

@Jolly47Roger: I also notice that the drawOrder is set to 20 (could maybe be made configurable) and also that the JPG images are compressed (albeit slightly) rather than simply stored. I think I read on Garmin's forum that it's preferable to simply store them with no compression to speed up map drawing on the GPS. I've unzipped and rezipped mine before transferring, but adding the parameter -mx0 to the command line will sort it.

I'll be taking my newly acquired 550t into the field tomorrow for the first time, so I'll see how it all works out in practice.

IrlJidel

Alun wrote: »

There is however a small, and variable over the map's area, discrepancy between the two overlays. Which is 'better' is debatable at the moment.

I've recreated the MAPC2MAPC map following your instructions and hints from Jolly47Roger ( I wasnt using a datums.txt file from GPSU).

I'm an eejit and did my testing on an incorrect .map file that only had 2 calibration points.

When I used my 4-point calibration .map file, I got results as good as the one created with MapMerge.

So great job, Jolly47Roger. MAPC2MAPC does the job in one easy step now.

Let me know if you are ever in Dublin as I owe you a pint!