The fundamental principle used by Photogrammetry is triangulation or more specifically called Aerial Triangulation. These lines of sight sometimes called rays owing to their optical nature are mathematically intersected to produce the 3-dimensional coordinates of the points of interest. Photogrammetry services in topographic mapping is well established but in recent years the technique has been widely applied in the fields of architecture, industry, engineering, forensic, underwater, medicine, geology and many others for the production of precise 3D data.
Remote Sensing is a closely aligned technology to photogrammetry in that it also collects information from imagery. The term is derived from the fact that information about objects and features is collected without coming into contact with them. Where remote sensing differs from photogrammetry is in the type of information collected, which tends to be based on differences in color, so land use and land cover is one of the primary output of remote sensing processing.
Remote sensing was originally conceptualized to exploit the large number of color bands in satellite imagery to create 2D data primarily for GIS. Nowadays remote sensing tools are used with all types of imagery to assist in 2D data collection and derivation, such as slope. Software tools today tend to hold a much wider range of image technologies such as image mosaicing, 3D visualisation, GIS, radar as well as softcopy photogrammetry.
He has worked in the digital mapping, remote sensing, and GIS industries for over 23 years. In practice, the camera axis is nearly held vertical. But due to unavoidable aircraft tilts the camera axis is unintentionally tilted from the vertical.
Then the resulting photograph is called tilted photograph. If tilt of the camera axis from the plumb line is less than 3 degree the photograph is called vertical. For tilt more than 3 degree, it is called tilted photograph. Tilted photograph may again be classified in two categorizes viz. Oblique photograph : An oblique photograph in which the apparent horizon appears is termed as high oblique photograph. Apparent horizon: it is the line in which the earth appears to meet the sky as visible from a point.
Low oblique photograph : is one on which the apparent horizon does not appear. A pair of low oblique taken in sequence along a flight direction in such a manner that both photographs cover basically the same area is called convergent photographs. Photographs may also be classified with respect to angular field of view of aerial camera as normal angle , wide angle and super ultra wide angle photograph. Photographs are normally exposed in such a way that the area covered by each successive photograph along a flight strip duplicates or overlaps part of the coverage of previous photograph.
This lapping along the flight strip is called end lap and the area of coverage common between two adjacent pair of photographs called in a flight strip is called stereoscopic overlap end lap. The pair of photograph is called stereo pair. The positions of camera at each exposure e. The photographs of two or more side lapping strips used to cover an area is called block of photographs. Requirements of Photogrammetry Technology.
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Learn how your comment data is processed. What Is Photogrammetry? The Basics of Photogrammetry The process of photogrammetry can vary, but the general idea revolves around gathering information about an object from photos of it. What Is Aerial Photogrammetry? What Is Terrestrial Photogrammetry? What Is Space Photogrammetry? Typically, aerial photos will fall under one of two categories: Vertical photographs: These images occur when the camera axis is vertical.
So, if you put the camera in an airplane, its lens would point down to the ground for a birds-eye view. Tilted photographs: Though the axis may be nearly vertical, tilts in the aircraft can cause an image to be unintentionally tilted in one direction. Within the category of tilted photographs, we have oblique photos, in which you can see the horizon line, and low-oblique photos, in which there is no apparent horizon. The classification depends on the level of tilt of the camera off of its vertical axis.
What Are the Principles of Photogrammetry? Necessary Features Some aspects are necessary for any photogrammetric model. These features include: Tie points: Tie points are coordinates that can be linked across multiple overlapping images. Typically, these are features present in both or all of your photos.
The tie points help the photo adjust with shared coordinates. They use known coordinates to position the image within the real world. Bundle adjustment: The adjustment helps to remove any distortion within a set of images. It reduces errors from real and predicted image points. Types of Photogrammetry While we can classify photogrammetry based on the location of the camera, we can also break things down by the type of photogrammetry being conducted.
Photo interpreters gather information about their subjects, such as characteristics and features, by analyzing and evaluating the photos carefully.
The job may involve remote sensing technologies. Remote sensing combines photo interpretation with data from remote sensing instruments, like cameras on satellites or aircraft and sonar systems on ships. Metric: In metric photogrammetry, the goal is to find measurements.
A researcher may pull specific data and measurements from a photo with the help of other information about the scene. Metric photogrammetry also covers planimetric and topographical mapping: Planimetric mapping focuses on planes and includes elements outside of elevation, like roads, rivers and lakes. It ignores these topographic features, only focusing on geographic objects.
Topographical mapping does the opposite, revealing the shape of the land and its elevations and contours. Uses of Photogrammetry The ways that photogrammetry comes to life can vary widely by collection method, data gathered, industry use and compatible technologies. Here are some of the places you can find it: 1.
Engineering In the world of engineering, drone photography helps to evaluate sites for construction, as well as create perspective images and 3D renderings. Military Intelligence Photogrammetry also plays a role in data gathering for military programs. Medicine While you might not think to put the medical field in the same category as land surveying, the 3D models that come from photogrammetric technology come in handy for a variety of health-related uses. Film and Entertainment Photogrammetry can play a big role in set design and world-building for a variety of films and video games.
Forensics Photogrammetry also plays a part in crime investigation. Construction and Mining Project engineers and contractors can use accurate 3D models to monitor and plan their worksites. Sports Analyzing athlete movements can help coaches and researchers understand more about their activities. Agriculture and Forestry In agriculture, aerial photos can offer insights into soil quality, irrigation scheduling, nutrition and pests. Search for:. If you are human, leave this field blank.
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