GDAL to CustomMap Tools

Some python scripts to generate Garmin CustomMap compatible KMZ from geo-referenced images.

Garmin CustomMap has some restrictions on the KMZ it can display

1. No tile larger than 1024x1024 (or equivalent total pixels)
2. No more than 100 tiles on the device (e.g. 4 KMZ files with 25 tiles each)

gdal2tiles (the GDAL default tiler) uses 256x256 tiles so requires 4 times as many tiles as necessary. gdal2kml tries to tile the map as efficiently as possible so you dont end up with thin tiles at the right or bottom.

gdal2kml DOES NOT do any warping so the source image must be correctly georeferenced and in EPSG:4326 projection or the conversion will fail. For other projections you need to get the GDAL utility programs and run it through gdal_warp first. If you are not sure about the projection run it through anyway as it will not adversly affect the output. This may introduce a black border which you can then cut out using the --crop option to gdal2kml.

gdalwarp -t_srs EPSG:4326 -r cubic <input.tif> <corrected.tif>
gdal2kml.py corrected.tif output.kml --crop 20

Requirements

You need the GDAL library and Python bindings installed. On Ubuntu its as simple as:

sudo apt-get install python-gdal

For windows there are prebuilt binaries at http://www.gisinternals.com The current stable is 1.9.0 and I have tested with the MSVC2008 version and the following packages but it can be a bit tricky to get all the paths right:

(http://python.org/download)
python-2.7.2.msi
(http://www.gisinternals.com/sdk/PackageList.aspx?file=release-1500-gdal-1-9-mapserver-6-0.zip)
gdal-19-1500-core.msi
gdal-19-1500-ecw.msi
GDAL-1.9.0.win32-py2.7.msi

Basic Usage

python gdal2kml.py input.tif my_map.kml
python kml2kmz.py my_map.kml

gdal2kml.py

Usage: gdal2kml.py [options] src_file dst_file

Options:

-h, --help	show this help message and exit
-d DIRECTORY, --dir=DIRECTORY
	Where to create jpeg tiles
-c BORDER, --crop=BORDER
	Crop border
-n NAME, --name=NAME
	KML folder name for output
-o ORDER, --draw-order=ORDER
	KML draw order
-t TILE_SIZE, --tile-size=TILE_SIZE
	Max tile size [1024]
-q QUALITY, --quality=QUALITY
	JPEG output quality 0-100 [75]
-v, --verbose	Verbose output

kml2kmz.py

Usage: kml2kmz.py [options] <kml>

Options:

-h, --help	show this help message and exit
-o FILE, --outfile=FILE
	Write output to FILE
-v, --verbose	Verbose output