MATLAB: Finding index between two parallel lines

bathymetryindexingindicesMATLAB

Hello,
I have bathymetry data (an intuition is attached here) which is stored in a regular 10m-resolution grid with the following limits:
  • In the x-axis: xmin:10:xmax. This contains 3039 columns
  • In the y-axis: ymin:10:ymax. This forms 1195 rows
  • The depth is Z matrix whose size is equal to 1195x 3039;
And I have 2 parallel lines crossing this bathymetry with the following information:
  • Line 1 is defined as points (x1,y1) and (x2,y2)
  • Line 2 is defined as points (x3,y3) and (x4,y4)
My task is to find indices between these two lines. Could you please help to solve this?
Many thanks
T

Best Answer

You can use inpolygon
clc, clear
xmin = 50;
xmax = 551;
ymin = -35;
ymax = -800;
y1 = ymax + 150;
y4 = ymin - 150;
k_up = (y1 - ymin)/(xmax-xmin);
k_down = (ymax - y4)/(xmax-xmin);
cla, hold on
for x = xmin:10:xmax
    y_start = ceil(y1 - x*k_up);
    y_end = floor(ymax - x*k_down);
    for y = y_start:-10:y_end
        plot(x,y,'.r')
    end
end
hold off
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