Photogrammetry is a technology that combines photography and geometry. The principle is very simple, yet it has a huge impact on current architectural works. What it does is something like this:
Photography gives 2D representations. The system generates 3D measurements of the surface and object from a photograph. Aerial and terrestrial are two major types of photogrammetry.
- Aerial photogrammetry
Cameras fit to a machine that flies take pictures, and with the system, these pictures are used to generate measurements. In this case, at least two photos of the same object or surface have to be taken for statistical comparison. Specially designed planes are used for this kind of photography.
The planes are made to fly over predetermined piece of land, pointed with specific landmark edifices. The camera speed is regulated according to the speed of the plane. Also, the height of the aircraft from the land is known. Stereos plotters are used to create the base contour of the surface being photographed.
- Terrestrial photogrammetry
In this kind of photogrammetry, a camera is used in a stationary position. The camera is positioned on an elevated level. The tilt and other specifications of the camera are all controlled.
- The difference
Both being branches of photogrammetry, aerial and terrestrial photogrammetry are used for mapping and measurement related issues. However, the methods are different, thus giving different results when at work.
a) Aerial photogrammetry requires a high-end infra support: specially designed and programmed planes being just one of them.
Terrestrial photogrammetry comparatively needs much less investment and technical skill to carry out.
b) The aerial kind of photogrammetry is suitable when we are trying to map a large piece of land. That is longitudinal knowledge and calculations are an integral part of this photogrammetry operation.
Terrestrial photogrammetry is a preferred method when designers and planners aim to monitor and map bridges, pipeline networks, transport network, etc. The axis of the camera takes care of the area surface to be covered.
Many state-of-the-art environmental projects that map the movements of glaciers use terrestrial photogrammetry methods. The static positioning of the camera produces a data set needed for this kind of studies
c) Security processes benefit from aerial photogrammetry in many cases. Finding archaeological sites also benefits from the fact that we get to see a large piece of land at one go.
Terrestrial photogrammetry is more suitable for movement related issues on a land mass that is relatively smaller than that covered in the other kind.
d) Urban planning takes advantage of both the methods. Using aerial photogrammetry, planners and designers collaborate on the best possible perspective for a specific project. An aerial view of the proposed project along with its surroundings helps to generate a clear idea about the right perspective.
Terrestrial photogrammetry, on the other hand, helps to see the interrelation between urban constructions, security issues, disaster management and many other issues benefit from this kind of analysis.
Using both kinds of photogrammetry can create a data set that will help us generate the most efficient and effective plan for any construction project. We at UAV Data Processing will assist you in the above matters to the best of our abilities.
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