Re: Fw: Graphing points with drop lines to a 3D surface

["Michael Bennett" <M.N.Bennett@warwick.ac.uk>]

Thanks for your response, Greg.

I've probably not made it clear exactly what I'm after: I would like the 
drop-lines to be drawn between the points and the surface (not down to 
zero). Therefore I don't think the gui is flexible enough (only appears to 
allow me to draw drop-down lines to zero).
The persp function may be a solution with a lot of manual effort: it may be 
possible to interpolate the surface to find where each drop line hits then 
use perspp (after constructing the original surface with persp) to add lines 
one by one, but this is not straightforward - is there no other way (esp. 
one that allows me to plot nice 32-colour plots)?
All the best,
Mike.


----- Original Message ----- 
From: "Greg Snow" <greg.snow@ihc.com>
To: <s-news@lists.biostat.wustl.edu>; <M.N.Bennett@warwick.ac.uk>
Sent: Wednesday, November 10, 2004 3:30 PM
Subject: Re: [S] Fw: Graphing points with drop lines to a 3D surface


> >From the command line:
> Look at the perspp (note 2 p's at the end) function.  With the 3d
> coordinates, perspp will transform them to 2d coordinates that you can
> use with segments, points, or lines to add things to a perspective plot
> (remember to save the output of persp).  Note that your added lines will
> be on top of the perspective plot without anything like hidden line
> removal.
>
> > From the GUI:
> Create the surface plot, click the mouse between the surface and the
> axes so that 3 green circles and a green triangle appear, select the
> data for the points and drop lines then shift-click on the plots3d
> button for "drop line scatter"
>
> hope this helps,
>
> Greg Snow, Ph.D.
> Statistical Data Center
> greg.snow@ihc.com
> (801) 408-8111
>
> > > > "Michael Bennett" <M.N.Bennett@warwick.ac.uk> 11/10/04 06:37AM >>>
> Hi, I'm hoping someone may be able to help me with a problem I'm having
> with graphing some results in s-plus: I'm trying to construct a plot
> where I need to draw a 3D wireframe surface of values of a response that
> I have computed over a regular (this is OK) then add some points to the
> graph with "drop-lines" to the surface to indicate how far the points
> are from the surface. How can I achieve this last step?
>
> Mike Bennett
>
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