Photogrammetry is the science of making measurements from photographs. It is a photography with a purpose – to accurately measure from it.
We use stereo photogrammetry using latest high-resolution aerial imagery to capture our 3D Models. The aerial imagery collection is done using fixed-wing aircraft. As the aerial mapping plane flies over a city area, it takes series of photographs which overlap by 60%. With each photograph its GPS position, height, tilt, pitch and roll are recorded. Using this data + camera calibration data (to eliminate lens distortion effects), the imagery is triangulated to its correct real-world coordinates.
In areas where two images overlap, we project one image into one eye, the second image into another eye and and this way we are able to see the Z value (depth). We then manually capture this point.