SGS Infotech Pvt. Limited utilizes an automated aerotriangulation process for triangulation, thereby minimizing manual work and operator intervention. Our approach combines point selection, point measurement, point transfer, and block adjustment in a single process. The orientation has following main steps.
The cameras lens forms a photograph by a bundle of rays. In stereo Photogrammetry a bundle of rays is reconstructed by calculating orientation parameters. In creating the ground model on a suitable scale, two orientation processes are accomplished.
- Inner orientation: Inner orientation is a process by which the image-forming bundles of rays for each photo is reconstructed, true in its geometry. The IO is the process to find the positions and orientation of the film coordinate system of the image obtained by scanner / camera. During this process fiducial points are measured. Before starting IO process, calibration data (i.e. calibrating focal length, radial lens distortion values) is entered in the system.
- Exterior Orientation: -The relationship with the object spaces is created by exterior orientation of centrally projected image space. Exterior orientation is achieved in two steps:
A. Relative orientation: Relative orientation is the process of establishing the angular relationship between two consecutive photographs, images, as it existed at the time of exposure to form stereomodel.This process orients one image relative to another image.
The software measures at least six conjugate parallax points on each image within a model and computes a rotation angles and coordinates of the oriented exposure station. During RO process, Y- parallax is eliminated / removed at six standard locations.
B. Absolute Orientation:
Absolute Orientation relates a model to the ground (object) coordinate system, which establishes a relationship between model coordinates and the true ground coordinates or in other words horizontalization and scaling of the model. During AO, known GCP's locations are measured in the relatively oriented model. This way absolute orientation creates three-dimensional ground coordinates within relatively oriented stereo pairs.
