| 21 April 2010
Some of you have been wondering why most of the trees appear on top of the houses, as in the image below.
Most of the data that we have seeded (pun intended) the Urban Forest Map with comes from the San Francisco Bureau of Urban Forestry and Friends of the Urban Forest. Both groups keep track of their trees based on the street address, not the exact latitude and longitude of the tree to several decimal places. In order for us to get them on the map, we had to geocode them, which is a method of translating addresses into lat/long. The geocoder's default is to place things in the middle of the parcel.
So one of the most helpful things we can do as Urban Forest Mappers is help move the trees to the right place. Any tree on top of a house belongs out on the sidewalk. (We know this because the data sources only include street trees.) So log in and use the satellite imagery to help us shift the trees to their proper spots! I took care of the one at the bottom:
