User`s guide

Feature Extraction
13 Use the Hough Lines block to find the Cartesian coordinates of lines that
are described by rho and theta pairs. Set the Sine value computation
method parameter to
Trigonometric fun ctio n.
14 Use the Draw Shapes block to draw the lines on the luminance portion of
the ROI. Set the parameters as follows:
• Shape =
Lines
• Border value = White
15 Use the Embedded MATLAB Function block to calculate the angle between
the two lines. Copy and paste the following code into the block:
function angle = compute_ angle(theta)
%Compute the angle value in degrees
angle = abs(theta(1)-t heta (2))*180/pi;
%Always return an angle value less than 90 degrees
if (angle>90)
angle = 180-angle;
end
16 Use the Display blo ck to view the a ngle between the two lines. Accept the
default parameters.
17 Use the Video Viewe r blocks to view the origin al image, the ROI, and the
annotated ROI. Accept the default parameters.
18 Connect the blocks as shown in the following figure.
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