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Creating custom maps with GoogleEarth

Started by csonni, December 28, 2010, 01:29:32 PM

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My bad.  I was referring to the app.
I'm considering these MacTopo DVD's to use along with MacGPS Pro.  I need to find out if I can export sections of the maps to use with my Garmin.
Any Mac user's out there using these along with MacGPS Pro?


Just spent a couple of hours layering a topo map over GoogleEarth and then sending the .kmz file over to my GPS.  On the first try, the Garmin stated the file was too big.  I found that I had used a 35 meg jpeg in the .kmz file.  I shrunk the jpeg down to below 3 megs (which Garmin apparently requires) and then re0did all the calibrating over GoogleEarth (not the easiest task).  Sent it to the GPS and it works fine.  The only thing is that I don't see any of the satellite imagery on the GPS that I see on GoogleEarth.  That's the whole reason why I created this custom map- to see actual satellite imagery on my map.  Any ideas why it isn't showing on my GPS?  I adjust the transparency to where it blended in well in GoogleEarth before sending it over.


The procedure you used only sends the image you imported (the topo map). It will not send the underlying Google image. There are Windows programs to rip imagery from Google, maybe also on the Mac, don't know.


So, the calibrating of the Topo over GoogleEarth was done just so the GPS could use it?  I sure would like to figure out how to get the imagery in there as well.  Any others feel free to chime in here.


Yes, that's correct. You georeferenced the map. To get aerial imagery into custom map format, you would need to do the same thing with an image that you downloaded separately.


I noticed tonight that there are certain buildings that are showing up on my GPS.  This must be from the GoogleEarth data.  Sure makes for a more interesting display on the GPS compared to the plain Topo maps.


Most states now have GIS sites that allow the download of high-res aerial photos for free.  These photos are updated frequently, and will probably be in either mrSID or JP2 format with an associated world file.  Another place for free aerials is the NAIP imagery site, but these may not be entirely up-to-date.  You might need GIS software for manipulating these into a more usable format.  

G-Raster freeware reads mrSID files and GeoTiff's and converts them in seconds to KMZ tiles for Garmin custom maps and I highly recommend downloading it.  It allows adjusting of resolution to reduce file size, and contains links to several sources of free raster imagery as well as software for geo-referencing rasters not having world files.  I recommend NOT geo-referencing yourself, as it is time-consuming to do correctly and you introduce error when doing so.  There are plenty of sources for free aerials and topos that are already referenced.

Also, check out OkMap freeware.  It has more in-depth functions if you need them.  I have not tried it yet but it seems like a nice piece of software.