From GoogleEarth to loading effect (gravity) at altitude

in six steps
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(1) Take a snapshot of GoogleEarth using PaintShopPro,

(2) Turn the sea cells:  white
      the origo point:      red

(3) Draw a 1-km precisely horizontal
     straight-line:          yellow.
     Recolor the endpoint so that the origo remains the only red point.
     Turn non-sea cells into: neither white nor red nor yellow.

(4) Save in uncompressed tiff
     and move to linux (Oload/),

(5) Use  convert

        convert Image3-uncompressed.tif Image3-uncompressed.txt

     Find the red point

        fgrep red Image3-uncompressed.txt    =>  (io, jo)

     Measure out the 1.0 km in units of pixels:

        fgrep yellow Image3-uncompressed.txt

    or
    awk -F, '/yellow/{sub(/:/,"",$2);print $1,$2}' Image3-uncompressed.txt |\
      minmax |\
        awk '{gsub(/\//,"",$0);print $7-$6}'   =>  r  [pixels/km]

(6) Calculation
    If the station is z meters above sea level, multiply z·r/1000   => dimensionless height z'

    Write a main program: Catch all white points,
    use subroutine dtile_grav  (Oload/afor/p/tilegrav.f)  to sum up the gravity effect.
    Box size = (1,1), load location = (i - io, j -  jo)
    Multiply with  G·ρ  and a tide coefficient [m]  =>  Loading effect at height.
    Program exists:  ~/OTEQ/PROG/OLOAD/hiresgsam.f
      program hi_resolution ! Newtionan gravity for site at altitude
c
c USAGE: hiresgam -a<alt> [-c] -f <file>
c
c -a<alt>   - station altitude in m
c -c        - correction for spherical earth
c -f <file> - The converted tiff file, see
c             http://holt.oso.chalmers.se/hgs/OTEQ/hires-loading-HOW.TO.html
c
c setenv ABSOFT_RT_FLAGS '-defaultcarriage'
c hiresgsam -a7.0 -f Image3-uncompressed.txt
c unsetenv ABSOFT_RT_FLAGS
c
c
DONE