How to create a 200m-wide rectangle around a cross-section line in GMT 6.3?

Q&A
1

I’m trying to create a cross-section visualization similar to

Reference image
Reference image1280×762 149 KB

where I need to:

  1. Draw a line between two geographic points (A: 104.475°E,29.40°N to B: 104.492°E,29.38°N)
  2. Create a rectangle that extends 100 meters on each side of this line (total width 200m)

I know how to draw the basic line using:

  echo "104.475 29.40" > line.txt
  echo "104.492 29.38" >> line.txt
  gmt plot line.txt -W1.,black,--

But I’m unsure how to:

  1. Calculate the perpendicular offsets needed to create the rectangle
  2. Ensure the width is exactly 200 meters in real-world dimensions
  3. Close the polygon properly to form a rectangle

Would someone be able to provide a GMT 6.3 solution that creates this buffer around my line?

2

Hi,
There may be two ways.

  1. use gmtspatial -Sb to get a buffer. However, the buffer is based on Cartesian coordinate, you may need to do projection before this. Or you can use buffergeo function in GMT.jl wchich supports Cartesian distance.
  2. use grdtrack -C to get cross profiles and reshape them.