Photogrammetry is a scientific method of measurements using photography. In essence, it is a measurement technology using the three-dimensional coordinates of points on an object are established through measurements taken using several (two to three) photographic images taken from different angles. The outcome is a map or drawing or a 3-dimensional model of an actual object or a scene. Most of the maps available today are creation of Photogrammetry or aerial photos taken using aircraft. Also, it can be considered as a reverse process which convert the 2-dimensional photograph to a 3-D image.

Photogrammetry is useful:
• to establish coordinates of the required object-points
• preparation of topographical and thematically maps
• developing rectified photographs or ortho-photos.photogram

The significant feature of photogrammetry is that without touching the objects measurements could be done. Another form of photogrammetry is Remote Sensing which was mainly focused on working with aerial photography and satellite imaging. On broader sense, it is used for object interpretation and object measurement. More precisely, the Aerial photogrammetry is mainly used to produce topographical or thematical maps or digital terrain models. The photogrammetry is very popular among architects, civil engineers, archaeologist, police and military establishments.

The photogrammetry can be classified into two areas:

1. Far range and Close range photogrammetry. The far and close range depends on the camera lens setting. For example, for close range, the lens setting is kept at finite values and whereas for far range the lens is adjusted to infinite or indefinite setting.

2. The Aerial photogrammetry can be considered as far range, on the other hand, the Terrestrial Photogrammetry is used for close range. In Aerial Photogrammetry the camera is fixed to an aircraft and is adjusted vertically or towards the ground. Several multiple overlapping photographs of the ground are captured when the aircraft glides along a flight path. Once the aerial photos are taken, these photos have to be processed using a stereo-plotter (which is an instrument that will allow viewer to see two photos simultaneously in a stereo view). These photos are also used to create Digital Elevation Model (DEM) using a process.

In close range Photogrammetry the camera is held close to the object and is usually it is hand held or mounted on a tripod. The close range is commonly used for non-topographic surveys. In other words, it is used to produce drawings or 3-D Models and cannot be considered producing topographic maps or terrain models. This type is commonly used (with normal cameras) to model buildings, engineering structures, Vehicles, films, etc.

Land Surveys Pty Ltd are land surveyors who can also provide 3d maps as part of their services in Western Australia.

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