The iD editor makes adding features to OpenStreetMap as easy as tracing on the map. But background imagery doesn’t always match up perfectly with the real world. Camera distortions, atmospheric conditions on the day the picture was taken, or the shape of the ground may cause imagery to appear shifted from where it should be.
How can you trust that the background imagery is accurate? The guidance in this post and the newly improved imagery offset tool, built by Kushan, can help.
First, consider existing features on the map, including any available GPS traces. If the area is well mapped, but the background looks shifted, the imagery is probably inaccurate.
Press B to open the “Background pane” and check the list of available imagery for the current location. Try switching sources to see which is the most accurate.
At the bottom of the “Background pane” is a control for fine-tuning the imagery offset. Drag anywhere in the grey target area to align the background imagery perfectly with the map data.
For more tips on editing with iD, find Kushan and me on Twitter.