[Paraview] I: 3D point cloud with color

Mon Feb 27 16:07:57 EST 2012

And here is an example python programmable filter that you can adapt
to produce a 3 component unsigned char RGB array.

ids = self.GetInput()
ods = self.GetOutput()

ocolors = vtk.vtkUnsignedCharArray()
ocolors.SetName("colors")
ocolors.SetNumberOfComponents(3)
ocolors.SetNumberOfTuples(ids.GetNumberOfPoints())

inArray = ids.GetPointData().GetArray(0)
maxV = inArray.GetRange()[1]
for x in range(0, ids.GetNumberOfPoints()):
  rF = 0.0;
  gF = 0.5;
  bF = inArray.GetValue(x)/maxV
  rC = rF*256
  gC = gF*256
  bC = bF*256
  ocolors.SetTuple3(x, rC,gC,bC)

ods.GetPointData().AddArray(ocolors)

David E DeMarle
Kitware, Inc.
R&D Engineer
21 Corporate Drive
Clifton Park, NY 12065-8662
Phone: 518-881-4909

On Mon, Feb 27, 2012 at 3:44 PM, Pat Marion <pat.marion at kitware.com> wrote:
> ParaView does indeed display points with RGB color values.  The colors must
> be in a unsigned char array (not any other data type) with 3 components.
> Then go to the display tab and uncheck the "map scalars" box, and you will
> see the points with color.  You can read more about the map scalars option
> in the online documentation here:
> http://paraview.org/OnlineHelpCurrent/Display.html
>
> Giulio, did you try the python programmable source that I posted in your
> original email?  It works for me on your supplied file, rgb.txt.  If you use
> this python programmable source, you can then use File -> Save Data to
> re-save the data as a VTP file that can be loaded using a standard reader in
> the future.
>
> Pat
>
>
> On Mon, Feb 27, 2012 at 3:19 PM, David Pont <David.Pont at scionresearch.com>
> wrote:
>>
>> Hi Giulio,
>>  I am also very interested in viewing XYZRGB data, and I have not had any
>> success in Paraview so far. I think the suggestion to use a vtp file instead
>> of a text file was simply another way to get data in to Paraview. But I
>> think the issue is how to use RGB values for coloring, regardless of how the
>> information is read.
>>
>> I hope I am wrong, but I don't think this is supported. Paraview (vtk)
>> uses lookup tables to map scalar attribute data to RGB values. It also
>> supports vector data, by using only one of the values, or magnitude, ie
>> still a scalar to RGB mapping. When I load your example vtp file the RGB
>> triplet is loaded as Normals_, and color options are then to use, X or Y or
>> Z or Magnitude.
>>
>> It seems like this should be easy, really we want to bypass the mapping of
>> scalars to color and have Paraview (vtk) use the provided RGB directly. But
>> I think this might require a completely new Mapper and/or other parts of the
>> rendering subsystem. Probably quite do-able for someone that understands the
>> inner workings of the rendering system?
>>
>> In the meantime you might be better looking for other tools that are
>> designed to display point clouds with RGB? This kind of data is becoming
>> more common. My interest is for LiDAR data where XYZRGB data is starting to
>> become available, but I have not actually encountered this yet so I have not
>> found a solution.
>>
>> Here's hoping I'm wrong and someone has a clever solution in Paraview...
>> otherwise perhaps it could be a feature request?
>>
>>  regards, Dave
>>
>> David Pont
>> Scientist - Forest Management Science
>> Scion
>> 49 Sala Street, Private Bag 3020, Rotorua 3046, New Zealand
>> DDI +64 7 343 5663
>> www.scionresearch.com
>>
>>
>>
>> -----Original Message-----
>> From: paraview-bounces at paraview.org [mailto:paraview-bounces at paraview.org]
>> On Behalf Of Giulio Reina
>> Sent: Monday, 27 February 2012 8:57 p.m.
>> To: paraview at paraview.org
>> Cc: andrew.amaclean at gmail.com
>> Subject: [Paraview] I: 3D point cloud with color
>>
>> Hi all,
>>
>> Following  David's suggestion, I came up with the code attached that turns
>> the starting data file (rgb.txt, of the type [X Y Z R G B] (the first three
>> vector columns specify the location of the single point and the last three
>> one its color in RGB space)) into a parsed vtp format. Unfortunately, when I
>> try to open the VTP file in Paraview (after applying a Glyph filter) the
>> results are not what I expect, i.e. one point red, one point green, two
>> points blue.
>>
>> I would greatly appreciate if someone could help me put reading correctly
>> the VTP file, I should admit that I'm not very familiar with the use of vtp
>> files in Paraview,
>>
>> Cheers
>>
>> Giulio
>>
>>
>>
>>
>> -----Messaggio originale-----
>> Da: David Doria [mailto:daviddoria at gmail.com]
>> Inviato: giovedì 23 febbraio 2012 02:48
>> A: giulio.reina at unisalento.it
>> Cc: paraview at paraview.org
>> Oggetto: Re: [Paraview] 3D point cloud with color
>>
>> >> I have been working with 3D stereo reconstruction. So, I have huge 3d
>> point clouds co-registered with color in this format [X Y Z R G B] (the
>> first three vector columns specify the location of the single point and the
>> last three one its color in RGB space). I have been trying to display the
>> data in Paraview without success.
>>
>> >>
>> >>
>> >>
>> >> I use the "table to points" filter to show the 3D coordinates but
>> >> then I
>> do not know  how to specify the color of each single point using its RGB
>> components. Can you please help me out?
>>
>> If you're more comfortable in c++ you could use VTK to parse the file,
>> construct a polydata, and then write a vtp file. Here are the examples you'd
>> need:
>> http://www.vtk.org/Wiki/VTK/Examples/Cxx/InfoVis/ReadDelimitedFile
>> http://www.vtk.org/Wiki/VTK/Examples/Cxx/IO/WriteVTP
>>
>> Then Paraview can easily read this vtp file.
>>
>> David
>>
>>
>>
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