Description of High Definition Maps from Wikipedia:
A high-definition map (HD map) is a highly accurate map used in autonomous driving, containing details not normally present on traditional maps. Such maps can be precise at a centimetre level. … HD maps are often captured using an array of sensors, such as LiDARs, radars, digital cameras, and GPS. HD maps can also be constructed using aerial imagery. … High-definition maps for self-driving cars usually include map elements such as road shape, road marking, traffic signs, and barriers.
HD maps are being produced by Tomtom, Nvidia and other giants for the purpose of autonomous driving but I believe they will have other applications. I have been trying to find sample HD maps for download but with no luck so far. It seems like an emerging field with great competition between the commercial companies, but perhaps some pilot project was made available to download, or a FOSS initiative has been launched? I would appreciate any piece of data, even abstract examples.