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Photometric stereo for outdoor webcams

: Ackermann, Jens; Langguth, Fabian; Fuhrmann, Simon; Goesele, Michael


IEEE Computer Society:
IEEE Conference on Computer Vision and Pattern Recognition, CVPR 2012 : Providence, Rhode Island, USA, 16 - 24 June 2012
New York, NY: IEEE, 2012
ISBN: 978-1-4673-1226-4 (Print)
ISBN: 978-1-4673-1228-8
ISBN: 978-1-4673-1227-1 (Online)
Conference on Computer Vision and Pattern Recognition (CVPR) <30, 2012, Providence/RI>
Fraunhofer IGD ()
3D scene reconstruction; photometric properties; camera calibration; Forschungsgruppe Capturing Reality (CARE)

We present a photometric stereo technique that operates on time-lapse sequences captured by static outdoor webcams over the course of several months. Outdoor webcams produce a large set of uncontrolled images subject to varying lighting and weather conditions. We first automatically select a suitable subset of the captured frames for further processing, reducing the dataset size by several orders of magnitude. A camera calibration step is applied to recover the camera response function, the absolute camera orientation, and to compute the light directions for each image. Finally, we describe a new photometric stereo technique for non-Lambertian scenes and unknown light source intensities to recover normal maps and spatially varying materials of the scene.