OpenOrienteering Mapper 

Preparing a Map on the PC

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The Android app cannot be used to create new maps because it would be cumbersome to setup the base maps there. Instead, maps should be prepared with templates and possibly georeferencing using the PC version of Mapper first and then transferred to the mobile device for surveying.

If you want to use live GPS display, the map must be georeferenced. There are several options how to do this:

Georeferencing when you create a new map

The first thing to do after creating a new map should be to load a georeferenced template. If you do not have one, you may use for example an OpenStreetMap export in case there is sufficient data at the map’s location. To do so, go to https://www.openstreetmap.org, locate the map region, and click ‘Export’. Then select an area which covers all of your templates and save the export as .osm file. This file can then be loaded into Mapper as a georeferenced template.

On loading the first georeferenced template, Mapper will show the georeferencing dialog. This may look a bit intimidating at first, but when loading a template, usually little needs to be changed there. First, the projection type should be checked. If you do not know which projection to use, just select UTM. Second, the magnetic declination should be entered to align the map with magnetic north. You may simply use the lookup button to look it up on the internet for the place of the template you loaded. However, be aware that the lookup only uses a model which may deviate from the real declination. It may be advantageous to check this in the terrain. All remaining values in the georeferencing dialog are already initialized using the newly loaded template, so you can then finish the dialog.

Then load all remaining templates and finish preparing the map. Non-georeferenced templates will need to be moved to match the location of the georeferenced templates.

Georeferencing when you use an existing map

In this case, the easiest way is to first create a new map with the same symbol set as the existing map. The old map can be selected as the symbol set source in the new map dialog to do this. Then load a georeferenced template as detailed in the paragraph above (use e.g. OpenStreetMap if you do not have a georeferenced template).

After that, load the existing map as template in the new map. Then use the alignment tools for templates to move the existing map to match with the new georeferenced template. When you are finished, import the existing map template into the new map file using the corresponding action in the template dock widget, and you should be done.

Attention: especially for old maps, the whole existing map may be locally distorted. In this case it will not be possible to match the old map and the georeferenced template and the only way to georeference the map is to do a tedious undistortion. Mapper does not provide a tool for this.


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