save matrices from loop

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Adrian Brown
Adrian Brown 2021-3-15
评论： Adrian Brown 2021-3-18
Hello,
I am using this code that estimate Optical flow of a given video.
My purpose is to create a matrix that contain all the flow values for all while loop.
vidReader = VideoReader('Tennis Ball.avi'); % Read the Video size of frame in a video is 240x352
opticFlow = opticalFlowFarneback;
%% Estimate Optical Flow of each frame
while hasFrame(vidReader)
frameRGB = readFrame(vidReader);
frameGray = rgb2gray(frameRGB);
flow = estimateFlow(opticFlow,frameGray); % get 4 parameters size 240x352 each
% I aim to get all the the values get it in flow for each videoframe
%size of the matrix must be 240x352*53 where 53 is the number of frames in
%the video
end
I really apprecaite any help

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Bob Thompson
Bob Thompson 2021-3-15
I could be wrong, but it seems like you just need to index flow.
vidReader = VideoReader('Tennis Ball.avi'); % Read the Video size of frame in a video is 240x352
opticFlow = opticalFlowFarneback;
%% Estimate Optical Flow of each frame
Frame = 0; % Initialize frame index
while hasFrame(vidReader)
Frame = 1; % Increase index for new frame
frameRGB = readFrame(vidReader);
frameGray = rgb2gray(frameRGB);
flow(:,:,frame) = estimateFlow(opticFlow,frameGray); % get 4 parameters size 240x352 each
end
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Bob Thompson
Bob Thompson 2021-3-18
I apologize for my own inability in this area, I hope it hasn't held you back too much.
That being said, I don't have a particularly elegant solution for you as I'm not very familiar with the opticalFlow object. For a more brute force solution see below for two options
OPTION 1
vidReader = VideoReader('Tennis Ball.avi'); % Read the Video size of frame in a video is 240x352
opticFlow = opticalFlowFarneback;
% Initialize stuff
frame = 0;
flow = struct('Magnitude',[],'Frame',[]); % Force flow to be a structure
%% Estimate Optical Flow of each frame
while hasFrame(vidReader)
frame = frame + 1;
frameRGB = readFrame(vidReader);
frameGray = rgb2gray(frameRGB);
flow(frame).object = estimateFlow(opticFlow,frameGray); % stores opticalFlow values to structure element
flow(frame).Magnitude = flow(frame).object.Magnitude; % Pull Magnitude out of opticalFlow object into structure
flow(frame).Frame = frame;
end
C = [flow.Magnitude];
OPTION 2
vidReader = VideoReader('Tennis Ball.avi'); % Read the Video size of frame in a video is 240x352
opticFlow = opticalFlowFarneback;
% Initialize stuff
frame = 0;
%% Estimate Optical Flow of each frame
while hasFrame(vidReader)
frame = frame + 1;
frameRGB = readFrame(vidReader);
frameGray = rgb2gray(frameRGB);
flow = estimateFlow(opticFlow,frameGray); % get 4 parameters size 240x352 each
C(:,((frame-1)*size(flow.Magnitude,2)+1):(frame*size(flow.Magnitude,2))) = flow.Magnitude;
end
Adrian Brown
Adrian Brown 2021-3-18
Dear @Bob Thompson I really appreciate any reply from you. from each suggestion I learned a new thing from you. The two option are very helpfull for me. Thank you for your time and all your suggestion.

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