There are a number of initiatives going forward including one in Canada but
it would appear that it should be possible to extract building footprints
fairly accurately using this method.
"I confirm that we (NRCAN) are working on a process to extract building
footprints from airborne LiDAR data "
"The quality of these footprints are totally depending on the quality of
the LiDAR data in input (density and classification) "
Note this is purely technical, currently OpenStreetMap has reservations
about using image scanning software because of quality issues so there will
be some issues on acceptance in OSM.
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