A laser-scanned track starts with a survey: technicians set up laser scanners around the circuit, and each scanner fires laser pulses and times their return to record millions of 3D points. That "point cloud" becomes the reference for the track's surface, curbs, bumps, camber and elevation. Developers then build the 3D model and connect the surface to the physics, so the car reacts to the same bumps the real one does. The process takes months.
What lidar is
Lidar (light detection and ranging) uses pulsed laser light to measure distances. Combined with position and orientation data, the returns form a dense set of points, each with three-dimensional coordinates, called a point cloud (NOAA). The scanner times how long each pulse takes to reflect back and converts that time into a distance (USGS).
Airborne lidar used for mapping is typically accurate to about 10 centimeters vertically, according to the USGS. iRacing says it looked at lidar from airplanes but chose to laser-scan at the track itself, and describes the result as millimeter-accurate for the surface and its bumps (iRacing).
How a track gets scanned
iRacing's president, Tony Gardner, described the company's process in an interview on its site from the early 2010s (iRacing):
- Before scanning, tracks were built from estimates. Papyrus, the studio that preceded iRacing, sent people with measuring wheels, levels and photographs.
- The first trial was at Lime Rock Park, where a contractor from Leica scanned for about 34 hours straight. After it worked, iRacing bought its own scanners.
- The scan data had to be converted into a form its track tools could use, and the full build that follows takes months.
- The surface is connected to the physics, so the car is driving on the scanned surface and reacting to it.
- Rescans happen when a real track changes; Gardner gave Phoenix as a track that had changed significantly. He estimated that redoing a track takes 50 to 75 percent of the work of building a new one.
What scanning captures
iRacing says its laser-scanned tracks reproduce cracks and pockmarks in the surface as well as the camber and undulations that give each circuit its character (iRacing). KUNOS says the circuits in Assetto Corsa were developed with laser-scan technology, including Monza, Silverstone, Imola, Mugello, Spa and Brands Hatch (Steam). The GT World Challenge describes the circuits in Assetto Corsa Competizione as recreated with laser-scan technology (GT World Challenge).
From point cloud to drivable track
The scan is only the starting point. Gardner explained that iRacing had to write software to convert the scan data into a form its own track tools could use, and that a team of artists and production staff then spends months building each track. Objects around the circuit, from buildings to fencing, are among the most time-consuming parts (iRacing).
Limits worth knowing
- Tracks change. A scan is a snapshot, so a modified circuit needs a rescan (iRacing interview above).
- Not every track is scanned. Assetto Corsa includes fictional tracks such as Black Cat County and Highlands (Steam).
- Street circuits are hard. Gardner called Long Beach a big project because of the buildings, lights, fencing and other objects around the course.
Why it matters when you drive
On a scanned track, braking bumps, crests and camber changes show up where they are in real life, and the force-feedback wheel and motion platform pass them on to you. Real-world reference points still work too. Read more in understanding racing lines and the history of racing simulators, or browse tracks.
Drive real circuits at your event
SimsForHire brings full-motion rigs on SIGMA Integrale 2DOF/3DOF electric motion platforms to corporate events, private parties, trade shows and brand activations. Delivery is free within 50 miles of Miami, and farther locations are quoted on request. See pricing or call (754) 228-5654.