Any thoughts on how to relatively easily define quadrants in a circle around a point? I’d like to ID the area between 315-45 degrees (N quadrant), 45-135 degrees (E quadrant), 135-225 (S quadrant), and 225-315 (W quadrant). I’ve come up with a couple of complicated ways and wonder if I’m missing an easier one?
Michael
Michael Barton, Professor of Anthropology
Director of Graduate Studies
School of Human Evolution & Social Change
Center for Social Dynamics and Complexity
Arizona State University
Any thoughts on how to relatively easily define quadrants in
a circle around a point? I¹d like to ID the area between 315-45
degrees (N quadrant), 45-135 degrees (E quadrant), 135-225
(S quadrant), and 225-315 (W quadrant). I¹ve come up with a couple
of complicated ways and wonder if I¹m missing an easier one?
v.mkgrid + a little script math seems like it could be pretty simple.
note r.buffer does use geodetic distance in lat/lon but v.buffer doesn't.
(so buffers correctly look like pears on the screen)
On 5/16/08 5:40 PM, "Hamish" <hamish_b@yahoo.com> wrote:
Michael:
Any thoughts on how to relatively easily define quadrants in
a circle around a point? I¹d like to ID the area between 315-45
degrees (N quadrant), 45-135 degrees (E quadrant), 135-225
(S quadrant), and 225-315 (W quadrant). I¹ve come up with a couple
of complicated ways and wonder if I¹m missing an easier one?
v.mkgrid + a little script math seems like it could be pretty simple.
note r.buffer does use geodetic distance in lat/lon but v.buffer doesn't.
(so buffers correctly look like pears on the screen)
Hamish
__________________________________________
Michael Barton, Professor of Anthropology
Director of Graduate Studies
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University
> Michael:
>> Any thoughts on how to relatively easily define
quadrants in
>> a circle around a point? I¹d like to ID the area
between 315-45
>> degrees (N quadrant), 45-135 degrees (E quadrant),
135-225
>> (S quadrant), and 225-315 (W quadrant). I¹ve come
up with a couple
>> of complicated ways and wonder if I¹m missing an
easier one?
>
> v.mkgrid + a little script math seems like it could be
pretty simple.
>
>
> note r.buffer does use geodetic distance in lat/lon
but v.buffer doesn't.
> (so buffers correctly look like pears on the screen)
Michael:
I think I need 'pie' slices of a raster circle.
add v.buffer + v.overlay into the mix with v.mkgrid angle=?
or raster eqivalent, g.region to make a 2x2 cell region (quadrants) then r.mapcalc + lat/lon-safe r.buffer?