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= Preferences > Map Settings = 

[[Image(source:trunk/images/preferences/map.png)]]

Settings for the map projection and data interpretation

== Map Projection ==

You can change the map projection method between Mercator, and some others. Be aware that projections maybe only valid for a certain area of the world.[[BR]]
The default projection for JOSM is Mercator. This projection has certain advantages, one of them is that geometric figures (e.g. circles and rectangles) aren't deformed when displayed.

When you use rasterized background imagery then you need to set a projection supported by the service providing this imagery. JOSM is not able to change raster images. When image projection and current settings do not match, you get warned.

You can also change the system of measurement here (Metric, Chinese, Imperial, Nautical Mile). You can also change ''system of measuremen'' from the [wiki:Help/StatusBar status bar].

== Map Paint Styles tab == #MapPaintStyles

In this section sources for displaying the data can be changed. Beside the internal styles also externals styles are presented and can be activated.


[[Image(MapPaintStylesPreferences.png)]]

See [wiki:Styles] and [Dialog/MapPaint Map Styles Toggle Dialog].

== Tagging Presets tab == #TaggingPresets
''If you want to learn how presets can also be added to the toolbar see - [Preferences/Toolbar Toolbar Customization]''[[br]]
''If you want to use presets or need complete reference of presets see [wiki:Presets Presets]''[[br]]
''If you want to extend presets with your own see - [wiki:TaggingPresets TaggingPresets]''

[Help/Concepts/Object#presets Presets] allow you to select predefined tags for [Concepts/Object objects]. From this area of the preferences menu you can choose which presets to use.

The preset list will be downloaded automatically, then you have two options:

=== Activate preset(s) from available presets ===

Use [[Image(source:trunk/images/preferences/activate-right.png,20)]] the blue, right arrow in the middle

[[Image(wiki:TaggingPresets:TaggingPresets.png)]]

''Note for developers'': [wiki:Presets#Createnewpresets you can extend this list with your preset].

=== Add a preset from the file ===

Include one from a URL or local file (or network-located file or file in a Dropbox alternative) by clicking on the [[Image(source:trunk/images/dialogs/add.png,20)]] plus button on the right.


Adding presets requires a restart of JOSM. Then the [wiki:Introduction#Presets tagging presets can be selected as usual].

== File Backup == #BackupSettings
If you save geo data to a local file and the file already exists JOSM writes the data to a temporary file (with the suffix {{{~}}}). It then copies the temporary file to the target file. 
In the File Backup settings you can specify whether JOSM should delete the temporary file or whether it should leave it as "backup" in the file system.

1. Go to the tab **File backup** in the Map Preferences
1. Select or deselect the checkbox **Keep backup files**

See [Action/AutoSave#Preferences AutoSave Preferences]
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Back to [Action/Preferences Preferences][[Br]]
Back to [wiki:/Help Main Help]