PHOTOMOD AT — Aerial Triangulation data collection
PHOTOMOD AT module is used to automatically measure tie points for image blocks in the sidelap and overlap areas. In addition to fully automatic
aerial triangulation, PHOTOMOD AT includes tools for interior orientation, as well as Ground Control Point search and measurement. AT measurements
are loaded into PHOTOMOD Solver for block adjustment.
PHOTOMOD AT workflow:
Interior orientation for film images defines the position and orientation of the film’s coordinate system relative to the coordinate system
of the source digital image. It is during interior orientation that the parameters of systematic film distortion can be taken into account.
The procedure used for interior orientation is dependent upon the fiducial mark data and can be accomplished in manual, semiautomatic
or fully automatic mode, as determined by camera type
Interior orientation for digital cameras is available in PHOTOMOD Core and requires entering only the camera parameters and axis orientation.
The interior orientation report contains complete information about process accuracy and can be used to search for possible errors.
Ground control point measurements
PHOTOMOD AT is used to recognize and measure ground control or check points on images. Point coordinate values can be imported from a text file
or entered “directly”. After coordinate values are input, points are measured on the images in semi-automatic or stereo mode. If the block has a
preliminary exterior orientation (e.g. from an on-board GPS/IMU system), PHOTOMOD is able to locate the approximate GCP position before the final
Relative orientation is implemented as a fully automated procedure that measures tie points on all images of the block. PHOTOMOD contains
powerful tools to control accuracy, based on vertical parallax, triplet residuals and other process parameters. The final manual addition and
editing of tie points are reduced to near zero in almost all cases. Nevertheless, all tools necessary for manual or semiautomatic point
measurement are provided
If an image’s exterior orientation parameters (EO) are known within an acceptable degree of accuracy, (as provided by precise on-board GPS/IMU systems or third-party bundle adjustment software),
the AT/Solver stage can be excluded from the workflow. In this event, simply load EO parameters (“Direct georeferencing”) and start
stereoprocessing or orthorectification.