Calculating a distance between a point and a contour along an axis

I would like to implement an code to realiyze the calculation between a point and a countour of an cloud point along the x axis in 2D (blue line).

The lines are drawn with line() and the redpoint is only temporary.

After that, I would like to make a code to calculate a distance with any angle (green line).

Could anyone give me a tip or help me for that?

Thank you in advance.

Answer 1

[KSSV]

Let O(x,y) be your red point.

You can get the blue line intersecting the contour using knnsearch.

If you want to draw a line of length L with angle a w.r.t horizontal i.e. blue line.

%L is the length of line and a is angle 
x2=x+(L*cos(a));
y2=y+(L*sin(a));
plot([x x2],[y y2])

[Minyoung Hong]

Can I know what do you mean with O(x,y)? Furthermore, is the function knnsearch only for between points or also between a point and somewhere on contour? Thanks.

[KSSV]

O is your red point. Knnsearch gives you closest point(s) in a set from a specified point(s).

[Minyoung Hong]

Thank you for your tip KSSV, but the corresponding position on the contour cannot be also a point, also just a position on a line. I would like to define the exact position on the line. Can I do it also with knnsearch?

[KSSV]

knnsearchgives point which is existing in contour data. If you want to find exact point,yyou can find the intersection between the blue line and contour points/ curve.

[Minyoung Hong]

Thank you for your suggestions @KSSV! I solved the problem using cross section. You gave me an Inspiration really!

[Matt J]

@Minyoung Hong if KSSV's answer led to a solution for you, you should Accept-click it.

[Minyoung Hong]

@Matt J Oh I am sorry. I did it now.