| Re: coordinates & transforms & plotting [message #42933] |
Mon, 28 February 2005 06:58 |
Ralf Schaa
Messages: 37
Registered: June 2001
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Member |
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Thanks again, David. I try figure that out with T3D.
David Fanning wrote:
> I'm not sure what a "basis" is, but a coordinate frame
> consists of an origin (perhaps what you are calling
> the basis) and three orthogonal axes. The origin of
> the IDL coordinate system is the (0,0,0) point in
> the lower-left corner of the window, with the X axis
> horizontal, the Y axis vertical, and the Z axis
> coming out toward you.
That's the interesting part...didn't know that the 'plot-view' frame is
this vector base I was talking about (which is spanning up the vector space)
Cheers (in german this is 'Prost' and we drink a beer, isn't it?) ,
-Ralf
>
>> 2.)
>> And how can I manipulate that in a way it takes *my* basis?
>
>
> Typically, in IDL you set up the 3D transformation
> matrix with calls to T3D. You set a new "origin" with
> the TRANSLATE keyword.
>
> Cheers,
>
> David
>
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| Re: coordinates & transforms & plotting [message #42934 is a reply to message #42933] |
Mon, 28 February 2005 06:28  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Ralf Schaa writes:
> Okay folks,
>
> 1.)
> I have refreshed linear algebra and if I have it right, there is not a
> unique basis for vectors or points in 3D...so what does IDL take as a
> basis when plotting in 3D?
I'm not sure what a "basis" is, but a coordinate frame
consists of an origin (perhaps what you are calling
the basis) and three orthogonal axes. The origin of
the IDL coordinate system is the (0,0,0) point in
the lower-left corner of the window, with the X axis
horizontal, the Y axis vertical, and the Z axis
coming out toward you.
> 2.)
> And how can I manipulate that in a way it takes *my* basis?
Typically, in IDL you set up the 3D transformation
matrix with calls to T3D. You set a new "origin" with
the TRANSLATE keyword.
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
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| Re: coordinates & transforms & plotting [message #42936 is a reply to message #42934] |
Mon, 28 February 2005 05:35 |
Ralf Schaa
Messages: 37
Registered: June 2001
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Member |
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Okay folks,
1.)
I have refreshed linear algebra and if I have it right, there is not a
unique basis for vectors or points in 3D...so what does IDL take as a
basis when plotting in 3D?
2.)
And how can I manipulate that in a way it takes *my* basis?
Cheers
-Ralf
Ralf Schaa wrote:
> Dear all,
>
> How does IDL determines the coordinate system when plotting in 3D ?
> Is the matrix in T3D ... ?
>
> Cheers
> -Ralf
>
> (After transforming an Orbit into a new frame, the Boxes of the RDplot
> are not like expected ... )
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| Re: coordinates & transforms & plotting [message #42937 is a reply to message #42936] |
Mon, 28 February 2005 05:23 |
Ralf Schaa
Messages: 37
Registered: June 2001
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Member |
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Thanks David!
David Fanning wrote:
> Ralf Schaa writes:
>
>
>> How does IDL determines the coordinate system when plotting in 3D ?
>> Is the matrix in T3D ... ?
>
>
> The 3D transformation matrix is stored in !P.T.
>
> Cheers,
>
> David
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