Thursday, 25 June 2015

Doigs Ballast Pit - Maps

Well this has taken a long time to put together because it's been so hard to get the aerial photo lined up with Google Earth. When a lot of the terrain covered is now under water you can understand that finding features to match up can be hard work. In the end the photo turned out to cover a lot less riverbank on the true west side than I thought it would.

The 2007 GE ended up being the easiest one to work with due to the amount of shadow in some of the more recent images which made it hard to match up features. 

Halfway to a map. The completed tracings ready to be imported into the map, where they will be checked for their alignment. Misalignment issues are fairly routine for many reasons; since the imagery we are using is not orthorectified, there is naturally distortion of the features, and it's usual that different aerial images will not line up all the way across; GE imagery that has misalignments at the edges is something you see all the time, and this naturally causes positioning errors all across the virtual globe.