Personal page of the author: http://cs.brown.edu/~dqsun/research/index.html
Original paper: http://cs.brown.edu/~dqsun/pubs/cvpr_2010_flow.pdf
Newer paper: Deqing Sun, Stefan Roth, and Michael J. Black. “A Quantitative Analysis of Current Practices in Optical Flow Estimation and the Principles Behind Them”. International Journal of Computer Vision (IJCV), 2013 [ pdf] [Source code]
Look inside the sources:
@alt_ba_optical_flow\
@ba_optical_flow\
...
compute_flow_base.m
itarates:
Iterate flow computation
Linearization update, for j = 1:this.max_linear. In the simple case
max_linear==1
, when I usex = A\b
solver for linear system. Probably for more complicated solversmax_linear > 1
compute_flow.m
calls pre_process_data (preprocessing, normalization, image pyramyd). Loop through iterations:
for ignc = 1:this.gnc_iters
Calls compute_flow_base.m
...
@classic_nl_optical_flow\
@hs_optical_flow\
data\
utils\
...
pre_process_data.m
– several preptocessing options for images. The first is texture decomposition. if no texture decomposition, scale image to [0, 255] range. Build image pyramyd. there is also following code:
% For segmentation purpose
data.org_pyramid_images = compute_image_pyramid(this.images, f,...
this.pyramid_levels, 1/this.pyramid_spacing);
data.org_color_pyramid_images = compute_image_pyramid(this.color_images,...
f, this.pyramid_levels, 1/this.pyramid_spacing);
In my case I don’t need segmentation and use simple OF method. It seems it’s just bad code design. Dig deeper.
...
estimate_flow_demo.m
estimate_flow_interface.m
load_of_method.m
– switcher that recursively initializes members of OF object. E.g. if you want to load ‘classic+nl-brightness’ method, it loads ‘classic+nl’ first:
case 'classic+nl'
ope = classic_nl_optical_flow;
ope.texture = true;
ope.median_filter_size = median_filter_size;
ope.alp = 0.95;
ope.area_hsz = 7;
ope.sigma_i = 7;
ope.color_images = ones(1,1,3);
ope.lambda = 3;
ope.lambda_q =3;
%ope.display = true;
and then applies the difference:
case 'classic+nl-fast-brightness'
ope = load_of_method('classic+nl');
ope.max_iters = 3;
ope.gnc_iters = 2;
ope.texture = false;