I've done a lot of research on this topic over the past 8 or 9 months, but I'm a GIS newb, so I may have overlooked some possibilities for finding/extracting this data.
A short list of resources I have researched (an exhaustive list would be very long):
- Tax Net USA - Text data on properties is free. You have to pay to get footprint images. I don't mind paying, but their search interface is cumbersome, and the images they provide are small raster PNGs with 'cruft' that I don't need, such as dimensions. Additionally, each image is 'divorced' from the real world - there is no lat/lon or compass orientation information in the images. On the plus side, the images are detailed and are often accurate to within a foot or so.
- ArcGIS - The Texas maps seem to have acceptable coverage and reasonably accurate building footprint polygons, but I have no idea how I would go from a street address to a vector graphic of the building(s) at the address using ArcGIS (or whether that's even feasible).
- OpenStreetMap - Very sparse coverage of buildings in the central Texas area, the area I'm most interested in.
I'm not frightened by a highly technical solution. I'm a software developer, so I'm willing to install, write and/or interface with software to do the job.
Requirements in order of importance: Vector representation, accuracy, "queryability" (publicly available API would be great), lat/lon & compass orientation info.
I'm OK with querying each address individually, on an as-needed basis, but a bulk dataset would also be interesting.