Ops Room Junkie:
Not sure if this may be of any use direct or non direct.
It was sent to me recently and apart from a very quick sniff around I have not used it, I think it is more use for topography rather than obstacles but might provide a road to another source idea?
Shuttle Radar Topography Mission
Those are moderate resolution topographical data (generally 1:250,000) obtained from the year 2000 Space Shuttle mapping mission. Although, an improvement for many parts of the world, those data do have holes in them and certainly do not map obstacles to the detail required for a takeoff flight path analysis.
Thus far, the only method that really works is highly competent on-site survey from the airport out to a considerable distance.
Pilots are routinely taking off from many parts of the world with incomplete obstacle data for takeoff flight path computations.