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Camera Calibration

The best method of getting camera calibration parameters for TerraPhoto is to derive the parameters from a calibration data set using TerraPhoto itself. When the calibration data set is captured, the camera is operated in conditions similar to the actual project data collection. In addition, the calibration task serves as good verification of the overall accuracy of all system components.

Calibration data sets are usually collected at specific locations. These calibration sites should provide optimal conditions for the data collection. They are described in Sections Calibration site for airborne systems and Calibration site for mobile ground-based systems.

If you do not have any calibration document to start from, you need to derive initial values for the calibration parameters yourself. This is outlined in Section Starting values from scratch.

Another way is to convert system-specific calibration parameters into a TerraPhoto calibration file. There are several common system calibration formats implemented in TerraPhoto that enable the conversion. The conversion is done by using the Tools / Convert from command in the TerraPhoto camera dialog. It is usually required to improve the converted calibration values with the normal calibration workflow in TerraPhoto.

TerraPhoto provides commands for the automatic creation of mission, camera calibration, and image list files for certain camera systems. More precisely, TerraPhoto is able to import the output files of those camera systems which provide the information necessary for creating the TerraPhoto files. The following system output files are supported:

Denmark oblique camera files - see Import Denmark oblique command.

Lynx system index files - see Import Lynx Survey command.

Pictometry system files - see Import Pictometry Survey command.

The result of the camera calibration is a set of calibration values that work nicely from one project to another. It is still expected that you have to fine-tune misalignment angles for each mission as the IMU initialization offset probably causes a small systematic error.