Photogrammetry

Photogrammetry is the science in being able to measure data contained within a photograph, and is therefore by definition a part of remote sensing.

Photogrammetry has been used since the times of World War 2 to create maps based upon overlapping aerial photographs. In these early times, each stereo pair was placed in a stereo viewer to create a 3 dimensional image of the terrain. These images where then measured and drawn to form maps of reasonable accuracy.

Following its introduction, stereo plotters were invented, in which the position of the aircraft including its twists was replicated improving the accuracy of the resulting map.

Today, it is possible to obtain measurements from a single image if some control points are known. The results can be very good.

Surveyors in private practice will, depending on circumstances engage a photogrammatrist to provide contour and detail surveys over large areas of land. This can be done quickly assuming that the imagery exists, and relatively inexpensively when compared with traditional survey techniques.

Photogrammetry is used as a planning tool to provide maps, detail and contour surveys, at crime scenes and even in building façade restoration. In some cases, the technology has been superseded by the introduction of laser Scanners that create a point cloud image, which is then manipulated into drawings and measurements. 

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Bossi SSSI Consulting Surveyors SMIC