For projects with emphasize on high resolution imagery that needs to be captured in a timely manner, we provide our time-tested photogrammetry services. We utilize the latest technology employing our drones equipped with RTK positioning and navigation, and processed with post-processing kinematic method, which will yield accurate results. 

To ensure data accuracy, we will establish a network of temporary ground control points with accuracy better than 5 cm to be established within the project area and distributed evenly. Ground Control Points are required to achieve the expected accuracy of the project. TOP Aerial will set up a temporary geodetic GPS base station located within the project area. This GPS base station serves as the reference station for the static data post-processing and analysis.

Principles of Photogrammetry

In photogrammetry, the displacement of an object caused by a change in the point of observation is called parallax. Stereoscopic parallax is caused by taking photographs of the same object but from different points of observation. This parallax can be used to deduce the relative elevation of any surface points on the object. The resulting elevation points will be classified into “ground” and “non-ground” based upon a general classification algorithm tailored for the project area as a whole. Data classification will be manually checked and edited against the captured digital imagery.


Overlap and Sidelap


Any conditions of restricted visibility such as smoke, fog, and haze will have a detrimental effect on the quality of photographic data and could cause delays in data acquisition process. The aerial photo data will be processed to a stage where it will be checked for completeness and accuracy before the survey team leaves the site. TOP Aerial will survey ground test points within the project area to be used as ground truthing data, enabling a measurement of the accuracy of the data.