a series of point coordinates are known, and their orientation (angle). Calculate gradient

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ZhG on 27 Sep 2013

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Commented: ZhG on 27 Sep 2013

For example, 10 points' coordinates are known, as (xi, yi) i =1 ... 10 and a corresponding angle of each point is known, as ai

How I can calculate the gradient of each point and How does it show an arrow on the image for each point?

Thanks.

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Image Analyst on 27 Sep 2013

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https://nl.mathworks.com/matlabcentral/answers/88413-a-series-of-point-coordinates-are-known-and-their-orientation-angle-calculate-gradient#answer_97962

How can a bunch of points in a 2D plane, scattered all over the place, have a gradient? How did you get the angle at those points, but not the magnitude ?

Anyway, you can use quiver to put arrows on the picture.

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ZhG on 27 Sep 2013

Open in MATLAB Online

 I did it like
u = c*cos(ai)
v = c*sin(ai)

c is a constant, 0.2 for example

quiver(x,y u, v)

ZhG on 27 Sep 2013

but the line with arrow is a little longer than I expected How can I control that?

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