Filling in Degrees in a Circle (Astronomy)

[Mensanator]

On Aug 22, 6:12 pm, "W. eWatson" <notval... at sbcglobal.net> wrote:
> The other night I surveyed a site for astronomical use by measuring the
> altitude (0-90 degrees above the horizon) and az (azimuth, 0 degrees north
> clockwise around the site to 360 degrees, almost north again) of obstacles,
> trees. My purpose was to feed this profile of obstacles (trees) to an
> astronomy program that would then account for not sighting objects below the
> trees.
>
> When I got around to entering them into the program by a file, I found it
> required the alt at 360 azimuth points in order from 0 to 360 (same as 0).
> Instead I have about 25 points, and expected the program to be able to do
> simple linear interpolation between those.
>
> Is there some simple operational device in Python that would allow me to
> create an array (vector) of 360 points from my data by interpolating between
> azimuth points when necessary? All my data I rounded to the nearest integer.
> Maybe there's an interpolation operator?
>
> As an example, supposed I had made 3 observations: (0,0) (180,45) and
> (360,0). I would want some thing like (note the slope of the line from 0 to
> 179 is 45/180 or 0.25):
> alt: 0, 0.25, 0.50, 0.75, ... 44.75, 45.0
> az : 0, 1,    2,    3,              180
>
> Of course, I don't need the az.

On Aug 22, 6:12 pm, "W. eWatson" <notval... at sbcglobal.net> wrote:
> The other night I surveyed a site for astronomical use by measuring the
> altitude (0-90 degrees above the horizon) and az (azimuth, 0 degrees north
> clockwise around the site to 360 degrees, almost north again) of obstacles,
> trees. My purpose was to feed this profile of obstacles (trees) to an
> astronomy program that would then account for not sighting objects below the
> trees.
>
> When I got around to entering them into the program by a file, I found it
> required the alt at 360 azimuth points in order from 0 to 360 (same as 0).
> Instead I have about 25 points, and expected the program to be able to do
> simple linear interpolation between those.
>
> Is there some simple operational device in Python that would allow me to
> create an array (vector) of 360 points from my data by interpolating between
> azimuth points when necessary? All my data I rounded to the nearest integer.
> Maybe there's an interpolation operator?
>
> As an example, supposed I had made 3 observations: (0,0) (180,45) and
> (360,0). I would want some thing like (note the slope of the line from 0 to
> 179 is 45/180 or 0.25):
> alt: 0, 0.25, 0.50, 0.75, ... 44.75, 45.0
> az : 0, 1,    2,    3,              180
>
> Of course, I don't need the az.

>>> for az in xrange(181):
	print (az,az*0.25),

(0, 0.0) (1, 0.25) (2, 0.5) (3, 0.75)
(4, 1.0) (5, 1.25) (6, 1.5) (7, 1.75)
(8, 2.0) (9, 2.25) (10, 2.5) (11, 2.75)
(12, 3.0) (13, 3.25) (14, 3.5) (15, 3.75)
(16, 4.0) (17, 4.25) (18, 4.5) (19, 4.75)
(20, 5.0) (21, 5.25) (22, 5.5) (23, 5.75)
etc.

But are you saying if you have two readings of tree tops

        *
        *
        *
        *
    *   *
    *   *
____*___*______


And you linearly interpret between them

        /
       /*
      / *
     /  *
    /   *
   /*   *
    *   *
____*___*______

that the area below the dashed line is assumed to be hidden?

That wouldn't necessarily be true, as the tree profile could
dip below the line.

        /
       /*
      / *
     / **
    /  ***
   /*  ****
    ** ****
___***_****____

Of course, if you take enough points, the open areas may be small
enough not to be practical to worry about.

> --
>             Wayne Watson (Watson Adventures, Prop., Nevada City, CA)
>
>               (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
>                Obz Site:  39° 15' 7" N, 121° 2' 32" W, 2700 feet
>
>                      Web Page: <www.speckledwithstars.net/>



> --
>             Wayne Watson (Watson Adventures, Prop., Nevada City, CA)
>
>               (121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
>                Obz Site:  39° 15' 7" N, 121° 2' 32" W, 2700 feet
>
>                      Web Page: <www.speckledwithstars.net/>