FLYORIENT Usage: orientation = FlyOrient(subset_frame, threshold) This function takes in a subset frame around the fly (calculated by FindFly) and discards the 3D data by placing points where the pixel intensity is larger than the user chosen threshold. Then, Principal Components Analysis (by way fot the pca1 function) is performed on the resulting scatter plot to find the direction of maximum variance --- this direction is taken to be the fly's (ambiguous) orientation. orientation is a vector consisting of two angles (complements) that comprise the body axis. The first element is an angle in the upper half plane; the second element is an angle in the lower half plane.

- pca1 PCA1: Perform PCA using covariance.

- FindFly FINDFLY

0001 function orientation = FlyOrient(subset_frame, threshold) 0002 0003 %FLYORIENT 0004 % Usage: 0005 % orientation = FlyOrient(subset_frame, threshold) 0006 % 0007 % This function takes in a subset frame around the fly (calculated by 0008 % FindFly) and discards the 3D data by placing points where the pixel intensity 0009 % is larger than the user chosen threshold. Then, Principal Components 0010 % Analysis (by way fot the pca1 function) is performed on the resulting 0011 % scatter plot to find the direction of maximum variance --- this direction 0012 % is taken to be the fly's (ambiguous) orientation. 0013 % orientation is a vector consisting of two angles (complements) that comprise 0014 % the body axis. The first element is an angle in the upper half plane; the 0015 % second element is an angle in the lower half plane. 0016 0017 % Written by Dan Valente 0018 % 11 October 2006 0019 0020 %Normalize frame data by pixel of maximum intensity 0021 subset_frame = subset_frame/max(max(subset_frame)); 0022 0023 % Put dots where fly is and do PCA on reduced data set 0024 [rows, cols] = find(subset_frame >= threshold); 0025 rows = length(subset_frame(:,1))-rows+1; 0026 x = [cols';rows']; 0027 [xnew, PC, V, data] = pca1(x); 0028 0029 % Find orientation vectors (two, mirrored across diagonal), and group into 0030 % upper half and lower half planes. 0031 a1 = PC(1,1); 0032 b1 = PC(2,1); 0033 a2 = -PC(1,1); 0034 b2 = -PC(2,1); 0035 if (b1 >= 0 ); 0036 orientUHP = atan2(b1,a1); 0037 orientLHP = atan2(b2,a2); 0038 elseif (b2 >=0); 0039 orientUHP = atan2(b2,a2); 0040 orientLHP = atan2(b1,a1); 0041 else 0042 end 0043 0044 % The vector we will return 0045 orientation = [orientUHP orientLHP]; 0046 0047 return;

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