Photogrammetry – maximising the benefits from drone aerial images

What’s photogrammetry?

You will find a number of fairly advanced definitions of drone photogrammetry software however the one I love best is actually “the use of photography in surveying and mapping to ascertain measurements between objects.”

Drones provide a cost effective approach to shoot huge number of aerial photographs. In raw format these pictures are actually terrific for fundamental visualisation of the area of interest. But in raw format, like any other images, they cannot be utilized for correct measurements as the pictures have optical distortions produced by the camera lens, sensor, perspective of the digital camera as well as numerous additional factors.

The pictures may be processed to get rid of these optical distortions and make what exactly are referred to as orthorectified images which have been correctly georeferenced. Successfully, these images have been calibrated so that the all of the pixels align accurately with an (X,Y,Z) 3 dimensional place in the real life. Based on the control methods used, the accuracy of georeferencing might be right down to under 3cm.

This particular processing is actually photogrammetry – it will take big volume of images as well as applies some very clever technology to create a single stitched together orthorectified image.

Just how does aerial photogrammetry work?

A photogrammetry flight requires planning to make sure that the proper images and control points are actually captured to create the necessary outputs. The digital camera is actually possibly set to point straight down capturing nadir images or even set at an angle to capture oblique images that are ideal for mapping vertical surfaces like buildings.

The drone is actually flown on a pre planned automated flight, taking several overlapping pictures. The overlap is in that case used to arrange the photographs and figure out exactly how all of them fit together in the one orthorectified image. Photogrammetry application utilizes advanced algorithms to align, stitch and process together the images and use the accurate georeferencing data.

The scale of the area of interest along with things like the necessary accuracy will figure out the number of images and control points that have to be shot and processed.

What outputs can aerial photogrammetry produce?

Photogrammetry delivers 2D and 3D outputs which may be seen as standalone models or maybe integrated into computer aided design (Geographic info or cad) systems (GIS) workflows. The kinds of outputs include:

Orthomosaic – an orthomosaic is actually a 2D map which is actually a thorough, georeferenced photographic representation of an area of fascination which could be utilized for correct measurements Digital elevation model – these provide a digital representation of the ground’s topography and surface area. Based on the requirement, these may or perhaps might not include buildings, vegetation and structures
Point cloud – a 3D visualisation of the area of interest made up of thousands or perhaps millions of georeferenced points

Here are a few examples of exactly how photogrammetry outputs are now being used:

Volumetric calculations – construction site materials, quarrying output and landfill capacity
Restoration projects – 3D visualisation of restoration projects like Notre Dame
Construction projects – managing construction progress against a 3D Building Information Model (BIM)
Coastal erosion – forecasting and monitoring the effect of costal erosion