I wish to create building footprints from the classification in our LAS files. I have filtered out the building points, using the point cloud filter. But I now trying to join the outermost points of the buildings, which I can't figure out how to achieve this. I understand that this may be a little hit and miss with the LAS classifications but I am happy to accept this. I am a inexperienced FME user.

The image shows the extents of the classification of buildings

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    I can't give you the proper (series of) FME transformer, but this may point you in the right direction. What you want to achieve is a convex hull, grouped by points within a certain distance (to have separate polygons for each building). The grouping part shouldn't be too complicated, I suppose, it's just about finding the proper distance between points to filter out all that belong to a single building. – Martin Dec 2 '15 at 7:39
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    Polygon from Point Cloud knowledge.safe.com/questions/5083/polygon-from-point-cloud.html – Mapperz Dec 2 '15 at 16:19

Have a read of the following link Concave Hull and the Alpha Value, which was what I was trying to achieve by joining the Classified LIDAR building data and creating polygons around clusters of these points. Secondly as suggested look at this previously posted question Polygon from Point Cloud. Or review the attached image with my workflow, very important to read the metadata that comes with the LIDAR data. Some of the issues I found was the density of points and I had issues with the classification of data with incorrect values placed on points, causing my buildings to come out incorrect/slither polygons through buildings (but it did what i was trying to achieve).Building footprints workflow.

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Best Way for free Building Footprint data. Use it once and you will get best output:

  • Go to Arc tool box add LAStools.tbx.

  • Drop down tool, you will see multiple of tools.

  • First click Las Ground provide Las file as input and run - It will give you output.

  • Now Run Las Height, provide Las ground output as input for Las height.

  • Now run Las Classify, Provide Las Height output as input for Las Classify.

  • Now run Las Boundary, Provide Las classify output as input for Las Boundary provide concavity - 8 best as per my study, Use option - Select Building.

Output will be your Building Footprint.

Note: Please don't change any options given in default by tool. I didn't change it and found the best output.

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