Orthophoto based roofs and facades technical drawings production

Aerostream provides roofs and facdes survey services using non-contact (remote) measurements. It is used as an alternative or in addition to ground-based laser scanning. The method is based on the photogrammetric 3D modelling using photographs of the building from various angles.

Work stages

  • high-resolution iamge capturing from drones and special devices
  • tacheometric surveying of markers
  • photogrammetric processing of survey results: generation of 3D-models, orthophotomaps, georeferencing
  • import of orthophoto into AutoCad
  • Orthophoto based technical drawing production

Our surveying equipment

For aerial shooting we use DJI Inspire with a X5 camera and in-house designed quadrocopter Aerostream001 with a Sony RX-1r camera and a geodetic GNSS receiver.

In addition, for shooting in hard-to-reach places, a 12 meters height mobile monopod with Sony RX-1r camera is used.

Photogrammetric processing

produced on a cluster of several workstations

 

Textured 3D model

model level of details:

 

Facades orthophotos creation

As a result of processing, an orthorectified image is formed on each facade, all distortions are removed, the image is in the orthogonal projection, the accuracy of the orthophotomap according to control points is of the order of 1 cm

Сreation of orthophoto based technical drawings

The development of technical drawings is carried out in the AutoCAD environment on the basis of a precisely georeferensed orthophoto

The facade orthophoto can be used for measuring and technical drawings creation:

 

Download Autocad facade orthophoto example (20Mb)

The technology allows obtaining an accurate 3d model of the object in the shortest possible time. Every detail and element is captured, so you can assess the condition of the facing layer of the facade.

Conclusions

The control measurements of facade sections and altitude marks by an electronic total station showed that for a particular model the measurement error did not exceed 12mm vertically and 8mm horizontally (for the whole model), which was caused by the error of projecting a point cloud from a spatial model to a plane. The maximum value of the discrepancy was on the surface of the roofing parapet, which is much deeper than the main plane of the facade. In the plane of the facade, the discrepancy did not exceed 5 mm.

The use of photogrammetric surveying allows to reduce the time of field work by 3-5 times comparing to traditional methods and decreases the total cost of works by 30-40%

Obtained 3D model

пример модели фасада здания (для загрузки на sketchfab модель упрощена в 9 раз!)

 

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