3D-scanning of a car body using photogrammetry


How to maintain accuracy and save time during 3D-scanning of bulky objects? Use the benefits of the base grids. Students of Moscow Polytechnic University managed to apply this method successfully in order to digitize a car for virtual testing.  

Several students from the Faculty of Mechanical Engineering specializing in Innovation decided to improve the aerodynamics of a racing car as their graduation project. In order to do so, they are planning to solve several tasks. The primary task involves scanning and reverse engineering, the secondary task involves virtual testing of the 3D model, assessment, and improvement of the aerodynamics of a car body, and, the final task involves design and production of a car body. Their approach needs time; therefore, we shall inspect the car body digitization stage first, then look at the other stages of this project and will keep you updated.

In order to maintain accuracy during the scanning and alignment of a large object, photogrammetry technique was used. Photogrammetry technique involves the collection of information about base points position. Markers were applied to the car body: 5mm uncoded (white with black dots) and coded (black with radial dashes). Then the scanner detects and memorizes those markers using the AICON photogrammetry system.

RangeVision Spectrum 3D scanner was calibrated for the specific scanning zone, and photogrammetry base grid was uploaded into ScanCenter NG software. Markers help the scanner to measure the space and the distance. As a result, engineers save time by reducing surface overlap at the scan boundaries. If the work does not require the 3D model of the whole object, distant sections are easily scanned without the spaces in between. The base grid accurately positions the scans in relation to the whole object. I.e.: relative position of the front and the rear bumpers are preserved.

Moreover, photogrammetry also helps with a scanning of the hard-to-reach surfaces. If you detach a spoiler from the car in order to be scanned and digitized separately, the system will virtually apply the markers with the base grid returning it back to its initial place. One of the benefits of Range Vision scanner that saves time is the HDR (double exposure) mode. This mode simultaneously scans an object using several exposure sets.

The base grid creation and 3D scanning process were completed within one working day. Now the students need to perform reverse engineering of the body elements and conduct aerodynamic test simulations. Range Vision team wishes them good luck and successful diploma presentation.