Understanding the Aerial Photography math model

Aerial Photography is a rigorous math model based on the geometry of a frame camera. This model can compensate for the effects of varying terrain and for the distortions inherent to the camera, such as the curvature of the lens, the focal length, the perspective effects, and the position and orientation of the camera. The computed math model calculates the position and orientation of the camera at time of image acquisition.

Select Scanned-film when your imagery is scanned from film or paper prints. The images often measure 9 inches by 9 inches in size and usually contain calibration (fiducial) marks. Typically, the imagery includes a camera-calibration report that provides data about the camera, such as the focal length, fiducial coordinates, and radial-distortion parameters.

Select Digital / UAV when your imagery consists of frame images that are generated from charge-coupled device (CCD) arrays. This imagery does not include a camera-calibration report. However, most companies that provide calibration services for scanned-film cameras can provide camera-calibration services for digital cameras. The minimum measurements required are the focal length, which is determined when the lens is set, and the chip size, which you can obtain from the camera manufacturer.

Select ADS when you want to orthorectify imagery collected by using the Leica airborne digital sensor (ADS).

Select Compute from GCPs and tie points to use known points, coordinates on the ground, such as DGPS applanix data, or both to establish the position of the camera when the image was acquired.

Select User input to import EO calculated in a previous project or by using other triangulation software.