Hi
Making maps in kml/kmz format with Google Earth using an graphical map image file is cumbersome.
Assigning the image map to geographical positions by placing and stretching the image is
exhausting and imprecise.
I guess, there are tools, where the image file can be placed near a reference map like OSM and make the geographical reference by placing points the both of these maps.
Do you know about such tools to make custom maps ?
Thank you
Kind regards,
Tom
Have a look at these
http://www.the-thorns.org.uk/mapping/
https://moagu.com/?page_id=155
The best approach is to start with imagery that is already georeferenced. Then it's just a matter of cutting it into tiles that meet Garmin's spec.
The other very useful tool is Mobile Atlas Creator (MOBAC)
http://mobac.sourceforge.net
I have adopted it as a method of distributing my own maps because of its versatility. The software runs on MacOS, Windows and Linux and can export maps that work on almost any platform - Android, iOS, Garmin Custom Maps, Magellan RMP and others.
The method I use to create maps in this format is rather complex, but the result is a system that's very easy for the end user. Here's one of many free maps on my site that uses Mobile Atlas Creator: https://boydsmaps.com/new-york-and-long-island-2017-orthoimagery/
I wrote a detailed tutorial for end users here: https://boydsmaps.com/docs/Using-Mobile-Atlas-Creator-with-Boyds-Maps.pdf
I make a lot of custom maps. I have found one of the biggest difficulties I have faced is that many maps use different "projections" than google earth or the garmin. A good example of this is the topo maps and imagery that come from the USGS. If you look at the map as provided from the USGS, it is mostly a trapezoid with the bottom slightly longer than the top - and more importantly if you look at the lat/long reference marks they are definitely not "square" as Google Earth is. This is probably done like this so a simple measurement on the paper map is "true".
In order to rectify this I find these reference marks and measure them, and I figure out where the tick marks should be in order to square off the image. I feed these measurements into free image manipulation software (imagemagick) using its "polynomial distortion" routine to force these tick-marks to be squared off. The end result is that imagemagick "streches" the image (pixel by pixel) so that everything is shifted into place.
http://www.imagemagick.org/Usage/distorts/#polynomial
That makes georeferencing the topo map (and the image file) trivial. They now have reference marks for the lat/long, and they are perfectly square as google earth needs. Additionally, the shadow images I make from DEM files are also squared off (the DEM data is on a squared-off projection), so now the projections on the topo map and the shadow image match - it really makes a difference.
Just out of curiosity - does the map you are trying to georeference have any sort of callibration markings on it? Is it a map I could download and take a peek at?
Jeff
MAPC2MAPC will reproject from most existing projections, doing the calculations automatically.
[I declare an interest : I wrote it]
Yes, I believe you and I have discussed MAPC2MAPC. I found when I used it, that it munged my images terribly. If I recall correctly, you stated that it was likely an API call you were making to windows - windows was altering the jpg compression and making my nice sharp topo lines into a blur...
I just found the email exchange we had - March 16, 2017 :)
I would say you were very responsive and helpful to my questions, though.
I would like to add that for most applications, I bet MAPC2MAPC is a terrific solution. In our email exchange, I referred to my process as having "stupid-high" standards which I may have to abandon. Well, I'm not smart enough to have abandoned them....yet.
qGIS is another way to re-project a map. Have only played around with it a bit myself (I use GlobalMapper) but qGIS is very powerful, and it's free. :) https://docs.qgis.org/2.8/en/docs/training_manual/vector_analysis/reproject_transform.html
Quote from: TomGo on July 19, 2018, 06:16:20 AM
Do you know about such tools to make custom maps ?
I use QGIS to produce raster maps as a georeferenced tiff file. Then convert to garmin compatible KMZ maps using G-Raster.
QGIS will also make georeferenced PDFs. The 3.2 version is still a work in development but worth getting started on versus the older 2.18 long term release version.
QGis comes with the osgeo4w shell which implements GDAL. It's command line but if you need the Clark 1866 ellipsoid for instance this is the app for you