3

I am evaluating Hurricane data that has a radius which 64kt wind speeds were observed for a specific event. The properties of a Hurricane dictate that the wind speeds change in each part of said hurricane. This data has specified where the maximum radius from the eye of the storm the 64kt winds are found in each quadrant: NE, NW, SE, & SW.

I have created four buffers for showing the different sizes (i.e. one buffer with the NE quadrant's data but it is buffering all sides. However, I am trying to figure out if there is a way to cut the buffers into the needed cardinal quadrants?

The goal is to then dissolve the four buffers for a point into one buffer that shows how the radius changes for each quadrant. I know you can buffer right left sides of lines but this is a little more complicated. Current buffers, each the maximum radius of observed wind speed for one quadrant.

(I am using 3.6 and have access to 3.4)

5

(1) Prepared a dummy data of two storm center, with "NE", "SE", "SW", "NW" fields which stores the 64kt-wind observed distance (meters, in my project CRS).

enter image description here

(2) Started Geometry by expression tool, which is in Processing Toolbox > Vector geometry.

enter image description here

(3) Gave this expression:

 combine(
  combine(
    wedge_buffer( $geometry, 45, 90, "NE"),
    wedge_buffer( $geometry, 135, 90, "SE")
    ),
   combine(
    wedge_buffer( $geometry, 225, 90, "SW"),
    wedge_buffer( $geometry, 315, 90, "NW")
    )
   )

(4) Output was like this.

enter image description here ... not nice :(

(5) Modified the expression slightly.

convex_hull( 
 combine(
  combine(
    wedge_buffer( $geometry, 45, 90, "NE"),
    wedge_buffer( $geometry, 135, 90, "SE")
    ),
  combine(
    wedge_buffer( $geometry, 225, 90, "SW"),
    wedge_buffer( $geometry, 315, 90, "NW")
    )
   )
 )

enter image description here ... better? (or even worse?)

Looking back, I am not entirely sure this is what you needed...

(Attempt 3)

convex_hull(
 combine(
  combine(
    minimal_circle(wedge_buffer($geometry, 45, 1, "NE")),
    minimal_circle(wedge_buffer($geometry, 135, 1, "SE"))
    ),
  combine(
    minimal_circle(wedge_buffer($geometry, 225, 1, "SW")),
    minimal_circle(wedge_buffer($geometry, 315, 1, "NW"))
    )
   )
  )

enter image description here

  • This all was exactly what I was looking for! I can actually use both methods for this project as a starting point. Thank you so much! – John S. Jun 9 at 5:27
  • 2
    Thanks @JohnS. I added third example, which looks more "natural" hurricane windy area to me (sorry, just hard-to-quit, will stop here). – Kazuhito Jun 9 at 6:20

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