Landscape Position Continued– absolutely relative position calculation <– Pics!

Input:

Output:

Landscape Position Continued– Median and ImageMagick

Highlighting ridges with 250ft buffer (on 2.5ft DEM) with just ImageMagick:


convert lscape_posit.png -median 100 median100.png
composite -compose difference lscape_posit.png median100.png difference_median100.png


Input:

Output:

BTW, median calculations of this size are slow, even in ImageMagick.

Landscape Position Continued– absolutely relative position calculation

I apologize in advance– this first post will be heavy on code, short on explanation. Landscape position, e.g. previous posts, can be trivial to calculate, but to make the calculations scalable to a large area, some batching is necessary. In this case, instead of a McNab index, we’re calculating the traditional GIS landscape position. Enter my favorite non-geographic tool, PovRay… . To the difference between, we’ll use PovRay in combination with imagemagick:

#include "transforms.inc"
#version 3.6;

#declare widthx=3425;
#declare heighty=1707.5;

#declare Aperture=300;
#declare Laps=20;

#declare Ind=1-pow(1-clock,1.2);
#declare PosX=cos(2*pi*Laps*Ind)*Aperture*Ind;
#declare PosY=sin(2*pi*Laps*Ind)*Aperture*Ind;

#declare Camera_Location = ;
#declare Camera_Lookat = ;

camera {
	orthographic
	location Camera_Location
	look_at Camera_Lookat
	right widthx*x
	up heighty*y
}

background {color  }

union {

	height_field {
		png "dem.png"
		scale ;
		translate ;
	}

	pigment {
		gradient x color_map {
			[0 color rgb 1]
			[1 color rgb 0]
			}

		scale 
		Reorient_Trans(x, Camera_Lookat-Camera_Location)
		translate Camera_Location
	}

	finish {ambient 1}
}

povray +Ilscape_posit.pov +Olscape_posit.png +FN16 +W1370 +H683 +KFI1 +KFF99 -D
convert lscape_posit??.png -average average.png
composite -compose difference lscape_posit.png average.png difference.png

In truth, I think I could do all of this in imagemagick, but it might not be fast enough. More testing to follow... .