The documentation shows a solution by using an additional scalar value and
a colormap:
The documentation is very thorough and shows a good example as well
http://docs.enthought.com/mayavi/mayavi/auto/mlab_helper_functions.html#points3d
import numpyfrom mayavi.mlab import *
def test_points3d(): t = numpy.linspace(0, 4 * numpy.pi, 20) cos
= numpy.cos sin = numpy.sin
x = sin(2 * t) y = cos(t) z = cos(2 * t) s = 2 + sin(t)
return points3d(x, y, z, s, colormap="copper", scale_factor=.25)
On Sun, Jul 22, 2018 at 4:39 AM <mys...@ravijoshi.info> wrote:
> Hi,
>
> Thank you very much. I almost reached there. points3d is working
> however, I am having a hard time in assigning colors to each point.
> Please see the code snippet below-
>
> -------------------------------------
> import numpy as np
> from mayavi import mlab
>
> # generate random data (just for checking)
> pts = 10 # number of points (just for checking)
> x = np.arange(pts)
> y = np.arange(pts)
> z = np.arange(pts)
> c = np.random.rand(pts, 3) #r, g, b values
>
> mlab.figure()
> mlab.points3d(x, y, z, color=c)
> mlab.show()
> -------------------------------------
>
> The above code throws following error-
> The 'color' trait of a GlyphFactory instance must be a tuple of the
> form: (0.0 <= a floating point number <= 1.0, 0.0 <= a floating point
> number <= 1.0, 0.0 <= a floating point number <= 1.0) or None, but a
> value of array([[...]]) <type 'numpy.ndarray'> was specified.
>
> It seems that the color is a tuple i.e., (r, g, b)in mlab.points3d()
> function and it is globally applied to all points. However, in my case,
> each point has a color value, which is different from others.
>
> The simplest thing which came to my mind is to assign each point one by
> one as shown below-
>
> -------------------------------------
> mlab.figure()
> for i in range(pts):
> mlab.points3d(x[i], y[i], z[i], color=tuple(c[i].reshape(-1)))
> mlab.show()
> -------------------------------------
>
> This works fine for a few points. However, I have approximately 40,000
> points and the above approach isn't working!
>
> -
> Thanks
> Ravi
>
>
> On 2018-07-21 22:12, Shankar Kulumani wrote:
> > This function will do exactly what you want
> >
> >
> http://docs.enthought.com/mayavi/mayavi/auto/mlab_helper_functions.html#points3d
> >
> > Example
> >
> > points3d(x, y, z...)
> > points3d(x, y, z, s, ...)
> > points3d(x, y, z, f, ...)
> >
> > On Sat, Jul 21, 2018, 03:12 <mys...@ravijoshi.info> wrote:
> >
> >> Hello,
> >>
> >> I am new to mayavi and I am trying to use mayavi in python to
> >> visualize
> >> a point cloud. I have a colored point cloud
> >> (PointCloud<PointXYZRGB>)
> >> stored in a numpy array of shape (40000, 4). The first three columns
> >> of
> >> this array are the position in 3D space (x, y, z) and the last
> >> column is
> >> RGB color packed in one using the following formulation-
> >>
> >> // pack r/g/b into rgb
> >> uint8_t r = 255, g = 0, b = 0; // Example: Red color
> >> uint32_t rgb = ((uint32_t)r << 16 | (uint32_t)g << 8 | (uint32_t)b);
> >>
> >> Hence, the point cloud contains 40,000 points in which each point
> >> has a
> >> color assigned to it.
> >>
> >> I want to know if it is possible to visualize it using mayavi
> >> python?
> >> Any sample code will be appreciated more.
> >>
> >> -
> >> Thanks
> >> Ravi
> >>
> >>
> >
> ------------------------------------------------------------------------------
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