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I'm a software engineer living in Brixton. I'm a keen hobbyist photographer - I initially got my GPS (a garmin eTrex) to geo-tag pictures. I've just started contributing to OSM, and I'm currently using JOSM to add a bit more detail around areas of London I'm familiar with.

JOSM Newbie Notes

Here's a few notes from my first couple of days working on OSM, using the JOSM editor (on OSX).

Mac-specific points

  • "Installing" JOSM on OSX is a cinch - just download and double-click the .jar file
  • Use a two-button mouse with a scroll wheel - it makes life much easier. Right-dragging moves the map, the scrollwheel zooms.
  • Remember that your ~/.josm directory will be invisible to the finder (does anyone know a way to change this?) so you'll have to move the plugins into it from the command line.
  • There's a Mac OSX look and feel under the Edit->Preferences menu; it doesn't actually change any functionality but it fits in ;)

Points for all platforms

  • Get the "mappaint" plugin - it makes it far easier to see what's going on in your maps (and even work out where on earth you are), at the expense of slightly higher processor load on your machine (my powerbook 12" copes fine)
  • Upload and download small areas, frequently. The less time you've got unstored or unchecked changes, the lower the risk of conflict with other users.
  • Always download an area before you start work on it, even if you have your own GPX data.
  • A "small area" to start with might either be that from a short GPX track you've taken, or about a 1km square around a known location. This equates to about 0.06 of a degree of latitude/longitude (give or take polar distortion), so enter an area about that size into the Connection -> Download from OSM -> Bounding Box.
  • Rural areas with less detail might work better with larger areas - the 1km recommendation is about right for a suburb of London.
  • Once you're viewing an area in JOSM, at whatever zoom level, the JOSM download dialog box will default to the currently viewed area.
  • It's very easy to select more than you expect to, particularly when making "ways". Open the "Current Selection" panel (alt-e, third button up on the left) to keep an eye on what you've selected.
  • Switch back to "select" mode regularly and click on nothing to clear your select list. Unfortunately there's currently no "select none" button or shortcut.

Why don't my changes appear?

  • Segments aren't rendered on the slippy map unless they have a specified meaning (and/or are converted to ways?) See Map Features for how to specify that your way is a road/railway etc, and what type. If you're not sure of the type (eg primary/secondary) be conservative and choose the lesser (eg secondary).
  • The slippy maps are only rebuilt fairly infrequently anyway. Join tiles@home to be able to rebuild your own in the osmarender layer.