To remove the sensor and terrain related distortions from raw aerial imagery, orthorectification is used. Orthorectification in photogrammetry includes the following inputs for processing viz. sensor information, orbital parameters, ground control, and elevation information. Geometric correction is done when there is inadequate information for orthorectification. Sensor characteristics, orbital parameters, rational functions, or elevation information are not relied upon in Geometric correction.

Random errors of spatial data are usually adjusted by employing a fine distribution of ground control points (GCPs) through the traditional orthophoto generation and orthophoto mapping process. Geometric correction is a process that measures the coordinates of all known spatial features that can be precisely located on the image. Ground Control Points (GCP) are collected from Global Positioning System (GPS) devices set in the field or in some cases referenced from an existing map. They are basically defined in a geographic (latitude and longitude) coordinate system or in a projected coordinate system. Traditional orthorectification processes utilize digital elevation models (DEMs). Sensor attitude and orientation are generally corrected by taking into account both exterior and interior orientation parameters of the sensor or camera.

During orthophoto generation, the breaklines, GCPs and feature layers are included to ensure the positional accuracy and tonal quality of the ortho photo imagery. The digital orthophoto are quality ensured by a team of engineers for any distortion, and positional accuracy, using the provided orthophoto maps and surveyed ground control points. Ground control points and camera calibration report are necessary for ensuring accurate, measurable and georeferenced image. Flight height or AGPS data if provided as input, helps to achieve precision in the process.

TGG digital orthophotography output provides valuable information about the terrain from which true distances, angles and areas can be measured. The ortho photos or ortho maps are merged together using ortho vista, and seam lines created, and edited, to ensure a seamless mosaic of the entire project area. Orthophoto mosaics are created by merging orthophoto or tiled together and then clipped to according to client specified dimensions.

The orthorectification of remote sensing imagery unites relief effects corrections and geo-referencing with high location accuracy. TGG Geomatics guarantee the best georeferencing and orthorectified output within your budget, meeting your delivery time. We were selected and honored by government entities in Europe for providing the best quality output meeting their delivery time.