Re: [Matplotlib-users] Is there a 3D version of the quiver plot?

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On 8 March 2013 03:19, Brickle Macho <bri...@gm...> wrote:

> On 8/03/13 8:37 AM, Damon McDougall wrote:
> > Correct me if I'm wrong, but would a 2D quiver plot on top of a
> > contour plot work?  What spaces does the surface map to/from?  If your
> > surface can be expressed as a function f:R^2 -> R then it's equivalent
> > to look at its level sets, rather than the 3D picture.  You can then
> > project the surface normals onto the plane and plot them with a 2D
> > quiver plot.  If you want to keep the z-component information, then
> > you could colour the arrows according to the angle they make with the
> > x-y plane.
> >
> > Does that make sense?
>
> My source is an image, so technically f:R^2 -> R.  Specifically I am
> using depth maps or (range image) what to visualise the
> surfaces/normals.   I was  planing on plotting the image as surface
> (hadn't work out how yet) and overlay the normal vectors.  I think a 2D
> quiver plot on top of a contour plot may provide a useful
> visualisation/interpretation of the process.
>

You always have the solution to install mayavi, a 3D plotting library. The
API resemble maptlotlib's and it supports 3D quiver plots.

Cheers,
N

>
> Thanks for the idea.
>
> Brickle.
> --
>
>
>
>
> >
> > I put the original feature request in, and I think it would be useful,
> > but often I still find it easier to process two dimensional
> > information.
> >
> > N.B.  The above will only work for *functions* f:R^2 -> R.  To
> > clarify, a sphere cannot be expressed this way, because the resulting
> > mapping would be multivalued.  Using this method, two distinct surface
> > normals may have the same colour.
> >
> > Hope that makes sense.
> >
> > Best wishes,
> > Damon
> >
> >> Brickle.
> >> --
> >>
> >>
> >> On 8/03/13 5:43 AM, Benjamin Root wrote:
> >>
> >>
> >>
> >> On Thu, Mar 7, 2013 at 4:25 PM, Eric Firing <ef...@ha...> wrote:
> >>> On 2013/03/07 9:19 AM, Benjamin Root wrote:
> >>>>
> >>>> On Thu, Mar 7, 2013 at 2:14 PM, Brickle Macho <bri...@gm...
> >>>> <mailto:bri...@gm...>> wrote:
> >>>>
> >>>>      I have a list of surface normals I would like to plot.  Is there
> a
> >>>> way
> >>>>      to plot a 3D vectors in matplotlib similar to how quiver plots 2D
> >>>>      vectors?
> >>>>
> >>>>
> >>>> Not at this time, but that would make a great feature request!  I
> think
> >>>> the current roadblock to such a function is a bug with converting 2d
> >>>> arrow objects into 3d arrows.
> >>> Quiver uses a PolyCollection, and I see that there is a
> Poly3DCollection.
> >>>
> >>> Eric
> >>>
> >>>> Ben Root
> >>>
> >> Took a bit of digging, but I knew I remembered this question before:
> >>
> >>
> http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CDMQFjAA&url=http%3A%2F%2Fmatplotlib.1069221.n5.nabble.com%2F2D-Quiver-in-Axes3D-td27944.html&ei=Pwk5UfGdLufv0QHuroD4BA&usg=AFQjCNEqlWv2vY5l2IPcje-g6B0U21wDNw&bvm=bv.43287494,d.dmQ
> >>
> >> And the feature request is here:
> >> https://github.com/matplotlib/matplotlib/issues/1026
> >>
> >> In the thread I pointed out a bug that I encountered.  I really hope I
> get
> >> some free time soon so that I can work on the various feature requests
> in
> >> mplot3d.
> >>
> >> Cheers!
> >> Ben Root
> >>
> >>
> >>
> >>
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