Q: How to set min/max for colormap when rendering a pointcloud?

[maxfreu]

Hi! I would like to set the range of the colormap when rendering a pointcloud; I only want a color gradient from e.g. z=0 to z=1 although there are points above and below that region. Is this currently possible? If yes, how?
Edit: I am using v0.9.0 btw

[germanros1987]

This is possible using the new API. @errissa could you please provide an example?

[ssheorey]

Hi @maxfreu please upgrade to the latest Open3D v0.14.1. Here is sample code for using the color gradient with the new API:

import open3d as o3d
from open3d.core import Tensor, concatenate
from open3d.visualization import rendering, draw
from open3d.ml.vis import Colormap

# Create a helix point cloud. We will use the Z values to assign colors.
values = Tensor.arange(start=0.0, stop=1.0, step=0.001,
                       dtype=o3d.core.float32).reshape((-1, 1))
period = 0.2
xyz = concatenate(
    ((6.28 / period * values).sin(), (6.28 / period * values).cos(), values), 1)
pcd = o3d.t.geometry.PointCloud(xyz)
# Use a special point property to specify colormap lookup values for the point
# cloud.
pcd.point['__visualization_scalar'] = values
# Use a default rainbow colormap
colormap = Colormap.make_rainbow()
# Add alpha channel and convert to Gradient Points
colormap = list(
    rendering.Gradient.Point(pt.value, pt.color + [1.0])
    for pt in colormap.points)
# Now create the material
material = rendering.MaterialRecord()
material.shader = "unlitGradient"
material.gradient = rendering.Gradient(colormap)
material.gradient.mode = rendering.Gradient.GRADIENT
material.scalar_min = 0.0
material.scalar_max = 1.0

draw({
    'name': 'helix',
    'geometry': pcd,
    'material': material
},
     point_size=3,
     show_skybox=False)

[maxfreu]

Thanks! It will take a while until I come around to trying it out, but good to know it works now. I leave it at your descretion to close the issue.