Photogrammetry Surveying, its Benefits & Drawbacks-

Introduction to Photogrammetry Surveying

The Photogrammetry is a surveying and mapping technique which has several applications in the Transportation Department. The practice of Photogrammetry Applications in surveying includes siteplanning, topographic mapping, earthwork volume estimation for proposed roads, a collection of digital elevation models (DEM), and image-based mapping (orthophotography).

The term “photogrammetry” is the combination of the words “photo” and “meter” it means measurements from photographs. The classical definition of photogrammetry is:

“It is the art, science, and technology of gathering reliable information regarding any physical object and the complete environment. This technique involves a process of record-keeping, measuring, and evaluating terrestrial and aerial photographs.

Photogrammetry refers to art because to obtain reliable measurements it requires specific skills, techniques, and decisions taken by an individual. Photogrammetry is a science and a technology because it uses images and modifies it, through technology, into significant results. The Modern photogrammetry involves image references and image forms different than photographs, like Radar images.

The photogrammetric process consists of proper project planning, image retrieval, image processing, control data for image adjustment, data accumulation and presentation of an end product results. The result of the photogrammetric method coordinates values of specific points, a realistic representation of the earth surface (topographic map), or a reformed image of the earth surface including map-like characteristics (orthophoto.)

Photographs used for photogrammetry are capture from a special (metric) camera, a typical camera or from digital sensors. The images are captured and recorded from a tool fixed on a satellite, on an aircraft as well as helicopters, or on a tripod (terrestrial photogrammetry) which is set up and mounted on the ground.

Benefits & Drawbacks of Photogrammetry

Here are few Benefits of photogrammetry over standard surveying and mapping methods are as follows:

  1. While capturing the Aerial photographs, photogrammetry produces an actual & permanent photographic record of a particular condition that exists while capturing images. Since the record has metric properties, it’s not only a pictorial record, but also it is an accurate, measured record.

The aerial images are useful for conveying or describing information to the public, State, including Federal agencies, as well as to other divisions of Transportation.

Here are some drawbacks:

Climate statuses (winds, clouds, haze, etc.) affect the aerial photogrammetry process and the image quality.

  1. Seasonal states affect the aerial images, i.e., snow cover will defeat the targets and defines a false ground impression. Hence, there is only a short-term period typically November through March that is perfect for common purpose aerial photogrammetry.

The accuracy of the mapping contours and cross regions depends on flight height and the efficiency of the field survey.

The Top Components of Photogrammetry-

In simple words, photogrammetry has three essential components. They are image control, image acquisition, and product compilation.

  1. Image acquisition covers planning the overflight, selecting a relevant camera system, photo capturing film processing, film review and annotation, printing of paper copies, and image scanning (if needed.)

Conclusion:

A successful photogrammetric survey project depends on a precise understanding of these components, Benefits and careful planning and execution of the project specifications.

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Source: https://blog.nibt.education/2018/03/photogrammetry-surveying-benefits/

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