Determining Light Direction in Spheres using Average Gradient

Using only the individual gradient vectors of a shaded image of an illuminated sphere, the position of the light source in a scene is computed. A two-part process, the proposed method determines both the two-dimensional planar direction of the light source, as well as its angular tilt above the image plane. Uncomplicated and therefore easily implemented, the method boasts an exceptionally fast run-time. It is currently designed for use in scenes involving a single point light source and a single shaded sphere, though it readily extends to ellipsoids, and, at times, textured spheres. In the case of arbitrary surfaces, only the two-dimensional planar direction of the light source may be estimated at this time. A formal proof of the proposed method, up to the two-dimensional planar direction of the light source, is also presented in this work.

[1]  Paul E. Debevec,et al.  Rendering synthetic objects into real scenes: bridging traditional and image-based graphics with global illumination and high dynamic range photography , 1998, SIGGRAPH '08.

[2]  Alistair Fitt,et al.  The closed-form integration of arbitrary functions , 1993, The Mathematical Gazette.

[3]  David J. Kriegman,et al.  Specularity Removal in Images and Videos: A PDE Approach , 2006, ECCV.

[4]  Wei Zhou,et al.  Estimation of Illuminant Direction and Intensity of Multiple Light Sources , 2002, ECCV.

[5]  David Salesin,et al.  Interactive digital photomontage , 2004, ACM Trans. Graph..

[6]  Baback Moghaddam,et al.  A Practical Face Relighting Method for Directional Lighting Normalization , 2005, AMFG.

[7]  Martin Jägersand,et al.  Wavelet-based Light Reconstruction from a Single Image , 2007, Fourth Canadian Conference on Computer and Robot Vision (CRV '07).

[8]  R. Risch.  The problem of integration in finite terms , 1969 .

[9]  Edward H. Adelson,et al.  Recovering reflectance and illumination in a world of painted polyhedra , 1993, 1993 (4th) International Conference on Computer Vision.

[10]  Xavier Granier,et al.  Intuitive Shape Modeling by Shading Design , 2005, Smart Graphics.

[11]  Michael J. Brooks,et al.  Shape and Source from Shading , 1985, IJCAI.

[12]  Edward H. Adelson,et al.  Estimating surface reflectance properties from images under unknown illumination , 2001, IS&T/SPIE Electronic Imaging.

[13]  Alfred M. Bruckstein,et al.  Global Shape from Shading , 1996, Comput. Vis. Image Underst..

[14]  Stephen Lin,et al.  Estimating Intrinsic Images from Image Sequences with Biased Illumination , 2004, ECCV.

[15]  Nathan Funk.  A Survey of Light Source Detection Methods , 2003 .

[16]  Miao Liao,et al.  Light Fall-off Stereo , 2007, 2007 IEEE Conference on Computer Vision and Pattern Recognition.

[17]  Yee-Hong Yang,et al.  Multiple Illuminant Direction Detection with Application to Image Synthesis , 2001, IEEE Trans. Pattern Anal. Mach. Intell..

[18]  Alan L. Yuille,et al.  Sources from shading , 1991, Proceedings. 1991 IEEE Computer Society Conference on Computer Vision and Pattern Recognition.

[19]  Azriel Rosenfeld,et al.  Improved Methods of Estimating Shape from Shading Using the Light Source Coordinate System , 1985, Artif. Intell..

[20]  Katsushi Ikeuchi,et al.  Light source position and reflectance estimation from a single view without the distant illumination assumption , 2005, IEEE Transactions on Pattern Analysis and Machine Intelligence.

[21]  Bertrand Kerautret,et al.  Reconstruction of Lambertian surfaces by discrete equal height contours and regions propagation , 2005, Image Vis. Comput..