Digital Terrain Models (DTMs) are digital representations of the ground surface or terrain. When captured photogrammetrically, these models nominally consist of breaklines and spot heights and depict the built and natural environment. However, the term DTM is generic and may also refer to the so-called 'bare earth', devoid of cultural features.

Applications of Photogrammetry

As photogrammtric mapping is most often utilised for object interpretation and measurement, it is appropriate for:

> Quarry and mining operations
> Railroad and road route location & planning
> Town and regional planning & design
> Vegetation & environmental monitoring
> Plus many more applications!

What equipment does Qasco use for DTM capture?

We currently operate with digital softcopy photogrammetric systems although we still offer "traditional" analytical photogrammetric procedures as well. Qasco was a pioneer in the development of hardware and software to upgrade analogue stereoplotters to computer-based analytical systems.

Analytical systems use photographic film diapositives as the basis for observations and rely on the experience and skills of the photogrammetrist to accurately set up models and record measurements. These systems are particularly useful with historical or archival imagery and data sets.

Digital softcopy photogrammetry is an efficient modern method for photogrammetric mapping. To create datasets using softcopy, the original aerial photographic film is converted to digital imagery with a radiometrically and geometrically calibrated scanner. To process the data, Qasco uses standard photogrammetric software such as Leica Photogrammetry Suite (LPS) and Microstation. These products transform raw imagery into geo-refernced data, as required for digital mapping, GIS and 3D visualisation applications. The data is supplied in digital form and/or as hard copy plots.

Qasco photogrammetrists are skilled on both systems and have extensive experience mapping different types of jobs. For nearly 50 years Qasco has been producing reliable and accurate photogrammetric datasets for a wide variety of applications to the satisfaction of clients. Contact us today to find out how our experience and expertise can benefit your project.

Other products that the photogrammetry department specialise in include:

> Aerotriangulation
> Topographic Mapping
> Earthworks Volumes