I have the following problem and question:
I have done some remote mapping based on available satellite imagery during the past four years, including some contributions to HOT/Missing Maps projects.
For some bigger mapping efforts of mine in Ethiopia I mainly have used Bing imagery, after it was by far the best and most clear one. Of course I know this can be different from area and area, so that there is no general answer to the general question “which imagery is the best?”
But now we have much more recent imagery from Digital Globe Premium. The differences in a developing country like Ethiopia are so big (at least in some parts of the county) that one can hardly use older mappings, especially for the buildings. Please take a look at one example, the town of Finchawa in Ethiopia, Oromia, West Guji Zone:
I have mapped streets and - mainly in the northeastern part of the town - buildings. If you zoom down to level 17 in Digital Globel Premium you can see that big changes took place, there are a lot of new buildings and a lot of changed and disappearing buildings. The problem is that it is not possible to zoom in deeper then level 17 using this recent imagery. Of course I can switch off the automatical zoom using JOSM, but then I get to an image I hardly can work with at level 19.
This is a problem we run into in several parts of the world.
My questions are:
- Would you keep on mapping buildings with the old Digital Globe Premium/Bing imagery, the one which “appears” if you zoom in to level 18 and deeper in JOSM?
- Do you know a good and suitable way to work with the much more recent Digital Globe Premium Imagery?
- If such great differences between the mapping done so far based on old imagery and new imagery exist, what would you do with the old data? Most of the mapped buildings can not be “used” any more, because they simply do not exist any more. New, other buildings are there and only very few buildings have just changed. But I feel unseasy and unhappy to delete and throw away thousands of buildings which were mapped correctly based on the old imagery.
Any ideas, any help and own experiences would be appreciated