[FRIAM] Simple Trig/Geometry challenge. Win a $50 Amazon card :-)

[Frank Wimberly]

Alternatively, bisect the segment S2 and draw a line from alpha to that
point.

---
Frank C. Wimberly
140 Calle Ojo Feliz,
Santa Fe, NM 87505

505 670-9918
Santa Fe, NM

On Fri, Jul 22, 2022, 2:38 PM Stephen Guerin <stephen.guerin at simtable.com>
wrote:

> Yes, that's what I was calling "splitting the slanted face" this morning.
> Keep going... :-)
> _______________________________________________________________________
> Stephen.Guerin at Simtable.com <stephen.guerin at simtable.com>
> CEO, https://www.simtable.com <http://www.simtable.com/>
> 1600 Lena St #D1, Santa Fe, NM 87505
> office: (505)995-0206 mobile: (505)577-5828
>
>
> On Fri, Jul 22, 2022 at 2:29 PM Frank Wimberly <wimberly3 at gmail.com>
> wrote:
>
>> Drop a perpendicular from the alpha vertex to S2.
>>
>> ---
>> Frank C. Wimberly
>> 140 Calle Ojo Feliz,
>> Santa Fe, NM 87505
>>
>> 505 670-9918
>> Santa Fe, NM
>>
>> On Fri, Jul 22, 2022, 1:34 PM Stephen Guerin <stephen.guerin at simtable.com>
>> wrote:
>>
>>> Today at Friam, I showed a small problem I was working on in
>>> photogrammetry. Attached is a Netlogo visualization of the geometry of the
>>> system.
>>>
>>> The problem is:  given an image where we know two star coordinates (RA,
>>> DEC), solve for the field of view of the image. We can get the spherical
>>> angle between the stars (alpha) and we know the principal point and two UV
>>> coordinates in the image. These create a right triangle pyramid and I want
>>> to solve for the height X (focal length). Here's a diagram.
>>>
>>> [image: rightTrianglePyramid.jpg]
>>> Law of Cosines can get all the interior angles of the bases with S1, S2,
>>> S3.
>>>
>>>
>>>
>>> _______________________________________________________________________
>>> Stephen.Guerin at Simtable.com <stephen.guerin at simtable.com>
>>> CEO, https://www.simtable.com <http://www.simtable.com/>
>>> 1600 Lena St #D1, Santa Fe, NM 87505
>>> office: (505)995-0206 mobile: (505)577-5828
>>>
>>
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