>On 24/09/2015 18:41, Phil Endecott wrote: >> You could easily trace building outlines from this > >This looks excellent, but being inherently lazy, is there any software >to convert what I assume are pixels outlines into vectors? > >It would save a *lot* of tracing. (Caveat: I'm not advocating mass import) > >Dave F. >
The New York public library's building inspector tool [1] has a solution for converting raster outlines of buildings to vectors. It works pretty well but for me the biggest drawback was that it detected the inside of buildings up to the inside edge of the walls and as such it was leaving gaps (the thickness of the wall) between terraced buildings. I was hoping that the chap behind Strava's slide tool [2] could improve the results (of the NYPL building inspector tool) by applying the "valley" approach of his algorithm to the blackness of the pixels on the raster map. He had a go one weekend but to no success. I wonder whether this dataset would be more suited (it seems to be perfectly suited to the "valley" algorithm!!). It would require a starting point so some vectorisation similar to the NYPL tool would still be needed. I wonder whether the right approach would be to extract the data straight from the LIDAR data rather than processing it to a raster image then doing edge detection on the raster. All the strava slide code is open if anyone wants to have a play [3]. Best regards, Rob [1] http://buildinginspector.nypl.org/ [2] http://labs.strava.com/slide/ [3] https://github.com/paulmach/slide
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