What is the difference between sparse and dense optical flow?

image-processing computer-vision opticalflow
Yücel Ceylan picture Yücel Ceylan · Jun 14, 2012 · Viewed 25.8k times · Source

Lots of resources say that there are two types optical flow algorithms. And Lucas-Kanade is a sparse technique, but I can't find the meanings of sparse and dense? Can some one tell me what is the difference between dense and sparse optical flow?

Answer

Rui Marques picture Rui Marques · Jun 15, 2012

The short explanation is, sparse techniques only need to process some pixels from the whole image, dense techniques process all the pixels. Dense techniques are slower but can be more accurate, but in my experience Lucas-Kanade accuracy might be enough for real-time applications. An example of a dense optical flow algorithm (the most popular) is Gunner Farneback's Optical Flow.

To get an overview of the flow quality look at the benchmark page e.g. the KITTI or the Middleburry dataset

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