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Multi-View Photometric Stereo

Lightsphere
Foto: Thorsten Richter

The goal of the Multi-View Photometric Stereo project is to employ controlled lighting to achieve fast and a highly accurate surface analysis and 3D reconstruction of an object. For the generation of illumination patterns, a large spherical metal frame (diameter 216 cm) is constructed from two moveable geodesic domes. The sphere is equipped with a total of 2202 RGB LEDs.

Using a microcontroller each of these LEDs can be individually regulated and each can emit a mixture of red, green and blue light. Driving all LEDs of the LightSphere requires only 6.2 milliseconds (160 Hz). Therefore, it is possible to display various lighting patterns in a very short time, which enables measuring dynamic objects. Through an easy-to-use software interface different lighting sequences can be created and passed to the hardware.

Photometric Reconstruction

One option for 3D reconstruction is to employ the so-called photometric stereo approach. By illuminating the object with several light patterns, the normal of a surface point can be estimated. When capturing an image with a camera, a surface normal it is determined for each pixel. With a high-resolution camera, it is thus possible, for example, to generate a 3D reconstruction of a face in which individual pores are recognizable.

Photometric Reconstruction

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