| Re: plot a circle in 3d with anisotropic axes [message #48730] |
Sun, 14 May 2006 23:27 |
Klemens Barfus
Messages: 45
Registered: December 2002
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Member |
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Thanks for your help, David !
Cheers,
Klemens
David Fanning wrote:
> Klemens Barfus writes:
>
>
>> I would like to plot a circle in a 3d plot [direct graphics], where the
>> axes are not isotropic. The circle should lie in the y plane. If I use
>> data coordinates I have to know the aspect ratio of z and y axis and
>> have to generate an ellipse ? In 2d I could use usersym where this
>> scaling is done automatically, but in 3d ?
>
>
> Use PLOTS with T3D keyword set.
>
>
>> How to get the ratio between the two axes ?
>
>
> ratio = (!Z.CRange[1] - !Z.CRange[0]) / (!X.CRange[1] - !X.CRange[0])
>
>
>> How to get the ellipse ?
>
>
> http://www.analyzemath.com/EllipseEq/EllipseEq.html
>
> See, for example TVELLIPSE or TVCIRCLE in the NASA Astronomy Library.
>
> Cheers,
>
> David
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| Re: plot a circle in 3d with anisotropic axes [message #48739 is a reply to message #48730] |
Fri, 12 May 2006 09:31  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Klemens Barfus writes:
> I would like to plot a circle in a 3d plot [direct graphics], where the
> axes are not isotropic. The circle should lie in the y plane. If I use
> data coordinates I have to know the aspect ratio of z and y axis and
> have to generate an ellipse ? In 2d I could use usersym where this
> scaling is done automatically, but in 3d ?
Use PLOTS with T3D keyword set.
> How to get the ratio between the two axes ?
ratio = (!Z.CRange[1] - !Z.CRange[0]) / (!X.CRange[1] - !X.CRange[0])
> How to get the ellipse ?
http://www.analyzemath.com/EllipseEq/EllipseEq.html
See, for example TVELLIPSE or TVCIRCLE in the NASA Astronomy Library.
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
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