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2. Path space similarity determined by Fourier histogram descriptors
 
 # Path space similarity determined by Fourier histogram descriptors

  ![](/sites/default/files/styles/wide/public/pubs/2014-07_Path-space-similarity/default.jpg?itok=IGOG9VCJ)

 We propose a simple technique for the efficient estimation of the similarity of light transport paths. Considering descriptors of the incident radiance, we improve both filtering \[Keller et al. 2014\] and caching based \[Ward et al. 1988\] variance reduction techniques for image synthesis that so far could not measure variations of material and lighting as they only included geometric measures of similarity, such as the divergence of normals, irradiance gradients, and the distance between vertices storing information.



 ## Authors



Pascal Gautron (NVIDIA)

Marc Droske (NVIDIA)

Carsten Wächter (NVIDIA)

Lutz Kettner (NVIDIA)

[Alex Keller](/person/alex-keller)

[Nikolaus Binder](/person/nikolaus-binder)

Ken Dahm (NVIDIA)

 

 

 ## Publication Date



Friday, July 4, 2014

 

 ## Published in



[ACM SIGGRAPH 2014 Talks](http://doi.acm.org/10.1145/2614106.2614117)

 

 ## Research Area



[Algorithms and Numerical Methods](/research-area/algorithms)

[Computer Graphics](/research-area/computer-graphics)

[Real-Time Rendering](/research-area/real-time-rendering)

 

 

 ## Copyright



Copyright by the Association for Computing Machinery, Inc. Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwise, to republish, to post on servers, or to redistribute to lists, requires prior specific permission and/or a fee. Request permissions from Publications Dept, ACM Inc., fax +1 (212) 869-0481, or <permissions@acm.org>. The definitive version of this paper can be found at ACM's Digital Library <http://www.acm.org/dl/>.