Op 25-sep.-2014 23:53 schreef "Wouter Hamelinck" <wouter.hameli...@gmail.com >: > > Hi Sander, > > Obviously I don't have a professional scanner. But don't underestimate > the work. I think that three minutes per map would be rather > ambitious. The list contains more than 300 maps. A quick and probably > optimistic estimate is 1000 minutes or 17 hours of work just for the > scanning. While you are at it, including maps that will get out of > copyright in a few years might sound like a plan. Depending on where > you put the cutoff that could add another 100 (only 40's) to 300 (if > also including a good part of the 50's) maps that I have. Anyhow, > count on easily a week of work. > You are right, I don't want to invest that time in something that > might eventually maybe be useful myself. I'd rather get out and map > one of the many remaining white spots on the OSM map in Belgium. > You don't need to own a professional scanner, there are lots of copy centres that offer digitizing paper. The prize to scan 300 to 600 pages would depend a lot on the page size and quality I guess. If the paper quality is still good, some of those professional scanners work completely automatic. The cost could be shared to make it less expensive.
Then you're left with a bunch of big files that could be bulk uploaded for later, crowd-sourced classification. > You can't compare the quality of 20th century maps with the 18th > century Ferraris map. Most of the cartographic know how dates from the > 19th century. I even don't think that Ferraris has a well defined > projection, while those topographic maps are a Bonne projection on the > Delambre ellipsoid. I assume that projection even has an EPSG code. > Also, from 1928 on the ICM (Institut Cartographique Militaire) started > working based on a denser triangulation. The precision is not like > modern maps, but certainly as good as the OSM precision. > > wouter Sorry, I was wrong about using mainly Ferraris maps, we used mainly Popp maps (so that's mid 19th century), with Ferraris only as a backup. Those did have a projection, and were mostly correct, though still very often had mistakes in their projection (mainly because lack of better tools). I also recently worked with American army maps from 1955 of West Africa. Of course they didn't have the time to do everything correctly for such an area, but they did have more means after WWII (like cheaper aerial pictures), but the maps still had many projection mistakes. I guess, to decide whether it's worth the effort or not, you could post a picture of how detailed the maps are, and probably also try to estimate the scanning prize when done in a copyshop. Regards, Sander
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