This page is incomplete. The Offset function is not described, yet.

Main menu > Imagery

This menu allows you to use various sources as a background layer in the main window. Clicking on a green imagery menu item will automatically download the image from the server. Servers can be added and edited using the preference tab in the preferences. Any new servers or changes would then displayed on the main imagery menu. By default, the major image providers are added. To use Yahoo! aerial imagery you will need to install a tool for interfacing with Yahoo to download tiles.

At present, the menu has following sections:

Image source

For each image source a menu point is added. When clicking on that menu you get a new layer with this image source.

Metacarta Rectified Image

For use with Metacarta's ​Map Rectifier.

Clicking on this opens up a dialog box requesting an id. The id is obtained from either the page url or the WMS link. (for example, ​http://labs.metacarta.com/rectifier/rectify/73 - the id would be 73)

Note if you are using these images for editing then you need to ensure the image, and its method of rectification, are free of any copyright issues.

Blank layer

In certain situations a blank imagery layer is needed (e.g. loading saved layers).

Using the WMS images

• Load / Download openstreetmap data and go to your favourite area
• Show the 'Layers' panel if it isn't showing already (Click the toggle button: [[Image:Liste aller Ebenen.png]])
• Click the menu option "WMS → Landsat" (or whatever named WMS server you want to use) This should cause it to create a new imagery layer.
• Wait a few moments for it to begin fetching image tiles.

As you pan around it will download more tiles. It also seems to remove tiles which are out of viewing area, to free up memory.

To remove the imagery and stop all WMS downloading, select the layer and click the trash can button. You can also temporarily toggle visibility of the layer (keeps imagery in memory). Right click on the layer (in the layers panel) to access further WMS layer options.

When your WMS layer is selected, the data layer is shown as deselected (dark grey). Simply select your data layer again (often called 'unnamed') to restore normal colours. It is also possible to display the WMS layer "above" the data layer, which will hide the data layer completely. Use the up/down arrows to fix the ordering.

You can adjust the positioning of the imagery by clicking [[Image:Adjust WMS-Layer.png]] button on the left. In this mode you can drag and drop the WMS layer. Press the button again to lock it in place. This can be useful if the imagery appears to be offset from reality, but note that your GPS unit isn't perfect. A bad GPS signal can cause an entire trace to have an offset from reality, so you may find it useful to check also by downloading other GPS traces recorded for the area.

You may need to adjust your map colours ('Edit' menu -> 'Preferences') to be darker or lighter, to contrast with the images you are using.

Basic troubleshooting

Things to try in case of problem.

no image appears, even after waiting a bit

• adjust zoom level so that the scale in the top left says ~150m, delete the layer (trash can icon), add it again from the menu.
• The plugin may not find the DLL files. Check you have placed all of the webkit-image zip file contents them somewhere on the system path.

images at bad resolution from Yahoo

• adjust zoom level as decribed above. Note that in most regions Yahoo imagery has a lesser resolution than Google Maps.

Exception occurred - red tiles

• This can mean the WMS server is temporarily not available. Landsat and OpenAerialMap seem to be prone to periods of non-availability. Delete the WMS layer and try again 10 minutes later.

error : bad parameters - red tiles

• Check that configuration -> projection is set to EPSG:4326 or Mercator.

gray tiles

• if you have non-ACSII symbols in the path to your plugin folder in Windows (e.g. cyrillic letters in your name in C:\Documents and Settings\your name\Application Data\JOSM\plugins), a possible solution is to change your name to an equivalent short filename. To find this open a command window and do dir /x "C:\Documents and Settings"

In its output the column to the left of your name should contain short version of your name, let it be for example 9335~1. Add a line to the batch file starting JOSM:

rem Contents of start_JOSM.cmd set APPDATA=C:\Documents and Settings\9335~1\Application Data start javaw -jar josm.jar

Caching

To reuse the tiles over JOSM sessions without having the reload them from the server, right click on the WMS layer and set a bookmark. During the next session, select the new WMS created by the bookmark in the WMS memu. Additionally, you may want to modify the following values in the preferences :

• cache.wmsplugin.expire -1 : this is a time in second until the tiles are invalidated. -1 means "never flush".
• cache.wmsplugin.maxsize 999999999 : maximal size of the cache (probably in MB)

Even though you have to download an area "manually", you can work offline using this technique.

Using a "Rectified Image"

Do not use copyrighted material, unless you have the right/permission to do so (see the Licensing section below)'''

Before you start with your own images, it might be a good idea to start with Landsat data so you'll learn how to work with these downloaded images.

To work with your own images in JOSM:

• upload your aerial image / scanned old map to either
  • Geothings at ​http://warper.geothings.net/ or
  • MetaCarta at ​http://labs.metacarta.com/rectifier/
  • Note: please read their privacy/copyright notes first
• rectify it on their site so it "fits with reality"
• XXX - wait for the image to be processed?
• remember the metacarta id (look at the URL in your browser)
• in JOSM, load some openstreetmap data of the expected image area (to be in the right "clipping range")
• click on Rectified Image and enter the id in the upcoming dialog

If the "clipping range" was wrong, you might see just nothing. In this case zoom out and retry the download.

Adding a WMS Server

Do not use copyrighted material, unless you have the right/permission to do so (see the Licensing section below)'''

To add a new WMS Server, use the Menu: 'Edit' menu -> 'Preferences' and click on the WMS tab. Now you can add / remove WMS server URL's.

A WMS server typically can provide different projections, subsets of data, etc., so you may need to experiment with the URL settings to get the best results.

Remote control

The "wms" remote control command instructs JOSM to open a WMS layer in the same way as with the "rectified image" menu command.

GET /wms?title=foobar&urldecode=false&url=...

where

parameter	required/optional	meaning
url	R	WMS URL in the usual format. This must be the last parameter.
title	O	Title (name) of WMS layer. If not specified the title will be "remote WMS".
urldecode	O	Disable URL-decoding of URL value if true. All other values will be URL-decoded anyway.
cookies	O	Can be used to specify cookies for the WMS request.

Note: The "url" parameter must be the last one. Everything after url= will be used as the WMS URL. It is not mandatory to URL-encode the value, but the WMSPlugin will try to URL-decode it unless urldecode=false is specified. If you notice that the decoding modifies the URL in an unwanted way, add "urldecode=false" before the "url" parameter.

This remote control function can be disabled by setting preferences value

wmsplugin.remotecontrol=false

or by using the checkbox "Allow remote control" in the preferences editor.

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