1. Lighting-up geometry: accurate 3D modelling with a torch and a camera George Vogiatzis, Carlos Hernández, Roberto Cipolla University of Cambridge, Toshiba Research

2. Our technique Aquire high-res mesh from images taken under changing camera position and illumination Changing illumination uncovers fine geometric detail Assumptions: –Lambertian surface, isolated highlights –Single, distant light-source –Silhouettes of object can be extracted

3. Image Acquisition Setup

4. In a nutshell: Estimate light direction in each image With known light directions can estimate surface normals n from pixel intensities i Integrate normals to get geometry n i l

5. Calibration object –Fully known geometry –Light can be estimated from intensity of all points Light estimation

6. Visual hull Light estimation

7. Virtual calibration object –Partially known geometry –Light can be estimated from intensity of correct points

8. Surface Evolution: Deformable 3D Mesh Evolve mesh until it is predicted appearance under recovered illumination matches images

9. Results

16. Advantages –Fully uncalibrated. Camera position and illumination are recovered from images alone –Low cost, practical and efficient alternative to laser range scanning –First image based method to obtain full 3D geometry of untextured objects