| Re: lat/lon from orb object [message #40638] |
Thu, 19 August 2004 17:12  |
Jeffrey R. Hall
Messages: 5
Registered: June 2001
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Junior Member |
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Yes, please! Currently my program uses idlexrotator to rotate in
data coordinates and the trackball to rotate in screen coords.
This gets messy quickly if the two are used w/o resetting, as you
might imagine. Moving the camera might work out better so I would
like to see what you've done with that.
I thought about deciphering the transform. The JPL SPICE toolkit
( icy version for IDL ) has some stuff for euler angles and so that
might be one way to go. It would hinder cross-platform portability
due to the extra installation requirements for SPICE so I'd prefer
a pure IDL solution.
Thanks,
Jeff
Rick Towler wrote:
> Well I suppose you could do something fancy with the transform that is
> returned by the trackball (I would start with the matrix and quaternion
> FAQ easily found by googling) or I would drop the trackball and use my
> camera object. And lucky day, I have a demo program with a map of the
> world which "rotates" using the camera (the camera actually rotates
> about the orb). It even prints out your approximate lat/lon. Understand
> that I put *zero* thought into the whole lat/lon thing so you'll
> probably want to use it as an example of what not to do. At any rate,
> you'll easily be able to get a lat/lon relative to the orb. Calculating
> a lat/lon relative to your texture takes a bit more work.
>
> Since the sysadmin (me) hasn't gotten around to configuring apache to
> export our public_html directories the code isn't currently online. I
> can email it to you if you desire.
>
> -Rick
>
>
> Jeffrey R. Hall wrote:
>
>>
>> Or, suppose I limit rotation to a single axis. How do I
>> determine how many degrees of rotation occured after
>> rotating it via the trackball object?
>>
>> Thanks,
>>
>> Jeff
>>
>>
>> Jeffrey R. Hall wrote:
>>
>>>
>>> I have an orb object with a map of the world that rotates
>>> with the trackball object. How do I determine the lat/lon
>>> at the center of the orb after rotation?
>>>
>>> I searched the archive and haven't found the answer.
>>>
>>> Thanks,
>>>
>>> Jeff
>>>
>>
--
Jeffrey.R.Hall@jpl.nasa.gov (818)354-4249
Member Technical Staff, Science Data Processing Systems Section (382)
Jet Propulsion Laboratory, Pasadena, CA 91109, Mail Stop 168-414
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