how to plot a section of a circle, need help with coding the math

Question

Bradley 2024-5-15

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回答： Image Analyst 2024-5-15

I minored in math but for some reason its always been tough for me to figure out coding math. I have foward looking sonar data and im trying to plot a section of a circle around the sonar. I attached a picture of what im trying to plot. The variables I have is center position (lat and long), I have right and left aperture (130° total), max range (usually 25-30 m), and rotation (heading). How do I plot this section of a circle? Thanks!

Just to add, Im not sure which r is the radius being plotted, the heading data I have pertains to the middle r in the picture, if thats not the r determining direction of the circle then I could probably subtract direction from the left or right aperture angle? Thanks again.

Second edit:

I figured out how to plot the circle using a different block of code that i found but im having trouble understanding how things are plotted. Below is an image of using the correct radius, theta, orientation and a position of 0,0. What line is being plotted here? I plotted a frame of the sonar at the correct heading and its at a different angle from the triangle plotted below. Thanks again for your help!

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Answer 1

Adam Danz 2024-5-15

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编辑：Adam Danz 2024-5-15

在 MATLAB Online 中打开

> The variables I have is center position (lat and long), I have right and left aperture (130° total), max range (usually 25-30 m), and rotation (heading). How do I plot this section of a circle?

I assume this is plotted in Cartesian coordinates and that the center point is defined by [latitude, longitude] which, in Cartesian coordinates, is [y,x].

center = [42.30027404055592, -71.35168003446316];

rightAp = 15; % deg

leftAp = 15; % deg

radius = 25; % max range

heading = 45; % deg

th = linspace(heading-leftAp, heading+rightAp, 100);

x = [center(2), sind(th) * radius + center(2), center(2)];

y = [center(1), cosd(th) * radius + center(1), center(1)];

plot(x,y, '-k');

axis equal

% Add reference line

hold on