1. IC CVLab, EPFL, 27218 Lausanne, VD, Switzerland, (e-mail: wangwei1990@gmail.com)
2. Artificial Intelligence, Xi'an Jiaotong University, 12480 Xi'an, Shaanxi, China, (e-mail: dangzheng713@gmail.com)
3. IC CVLab, EPFL, 27218 Lausanne, VD, Switzerland, (e-mail: huyinlin@gmail.com)
4. IC CVLAB, EPFL, Lausanne, Vaud, Switzerland, CH-1015 (e-mail: pascal.fua@epfl.ch)
5. IC - CVLab, EPFL, Lausanne, VD, Switzerland, 1015 (e-mail: mathieu.salzmann@epfl.ch)