[vtk-developers] vtkPointCloud remote module

Geoff Wright gpwright at gmail.com
Fri Jan 29 10:26:19 EST 2016


Hi Will,

That sounds good.  For my use case I do have a couple of scalar quantities
associated with each point, in PCL terminology I use pcl::PointXYZHSV.  For
interpolation of scalar values I think the ideal would be a parameter on
voxel grid that can accept either VTK_NEAREST_INTERPOLATION,
VTK_LINEAR_INTERPOLATION or VTK_CUBIC_INTERPOLATION a la
vtkVolumeProperty.h.  However, if this is too much work I think a linear
interpolation implementation would be fine for most use cases.

Let me know when you push the changes, I'll try it out.  Just checked your
gitlab repo and didn't seem them there yet.

G




On Fri, Jan 29, 2016 at 10:07 AM Will Schroeder <will.schroeder at kitware.com>
wrote:

> Geoff-
>
> I knocked out a vtkVoxelGrid last night, it seems to work great. It's
> threaded and seems to be fast.
>
> Question for you before I push the work to the repository: averaging
> points in each bin provides a nice subsampled point position. But what do
> you think we should do for attributes (e.g., scalars, vector, etc.)? These
> could be averaged too. There are however other options like finding the
> closest point to the subsampled point and using those attribute values, or
> if you want to get really fancy, using an interpolation kernel to
> interpolate to the subsampled point.
>
> Thoughts?
> W
>
> On Thu, Jan 28, 2016 at 10:03 AM, Will Schroeder <
> will.schroeder at kitware.com> wrote:
>
>> Thanks for the feedback. I have some downsampling filters in the works
>> now, I'll let you know when I have something ready.
>>
>> BTW we are on a similar path. PCL is awesome, but we have some common
>> workflows that would be better served with more compact software
>> environments, and with minimal IO and/or data transfer. So we're trying to
>> knock of a small kernel of capability to achieve this.
>>
>> Best,
>> W
>>
>> On Thu, Jan 28, 2016 at 9:56 AM, Geoff Wright <gpwright at gmail.com> wrote:
>>
>>> Hi Will,
>>>
>>> This is good to see.  I'm currently using VTK to generate surfaces from
>>> some point cloud data.  I have some initial pre processing steps that I use
>>> PCL (point cloud library) for, and then a vtk stage that converts PCL point
>>> cloud into vtkPolyData/vtkPoints.  It would be great to eliminate the
>>> PCL dependency and use exclusively vtk.  My point cloud data grows very
>>> large over time with a lot of redundant points so its very important to
>>> downsample them onto uniform spacing (
>>> http://docs.pointclouds.org/trunk/classpcl_1_1_voxel_grid.html ) before
>>> processing them in vtk.  Would it make sense to add something like this to
>>> your library?
>>>
>>> Geoff
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> On Thu, Jan 28, 2016 at 9:12 AM Will Schroeder <
>>> will.schroeder at kitware.com> wrote:
>>>
>>>> FYI- I have committed an initial set of filters for performing point
>>>> cloud processing. Any feedback or suggestions are welcome as this is an
>>>> initial prototype. The work is currently available as a remote module to
>>>> VTK (vtkPointCloud) via this repository:
>>>> https://gitlab.kitware.com/vtk/point-cloud.git
>>>>
>>>> A couple of notes:
>>>> + Right now I am using vtkPolyData to represent the point cloud via a
>>>> vtkPoints instance. There are no vtkVertex, vtkPolyVertex cells created to
>>>> save on memory.
>>>> + The classes will process as input any vtkPointSet dataset
>>>> + There is a general framework for filtering point clouds via the class
>>>> vtkPointCloudFilter. Besides their filtered cloud output, these filters
>>>> also have an optional, second output which contains any points removed from
>>>> the input.
>>>> + Current filters include vtkRadiusOutlierRemoval,
>>>> vtkStatisticalOutlierRemoval, vtkExtractPoints (extract points using an
>>>> implicit function). Some of  these names are inspired by PCL
>>>> <http://pointclouds.org/> names.
>>>> + All filters are threaded using vtkSMPTools using a threaded locator
>>>> (vtkStaticPointLocator) so I believe that this is relatively fast, although
>>>> I have not done much testing.
>>>> + I'm using vtkPointGaussianMapper in the tests, a class that Ken wrote
>>>> that is very fast.
>>>>
>>>> As usual comments and suggestions are requested. In particular any
>>>> suggestions for other filters to write are welcome (to round out some of
>>>> the core functionality). The repository is in flux as I try crazy ideas and
>>>> try to educate myself, so be forewarned.
>>>>
>>>> Best,
>>>> W
>>>>
>>>>
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>>
>>
>> --
>> William J. Schroeder, PhD
>> Kitware, Inc. - Building the World's Technical Computing Software
>> 28 Corporate Drive
>> Clifton Park, NY 12065
>> will.schroeder at kitware.com
>> http://www.kitware.com
>> (518) 881-4902
>>
>
>
>
> --
> William J. Schroeder, PhD
> Kitware, Inc. - Building the World's Technical Computing Software
> 28 Corporate Drive
> Clifton Park, NY 12065
> will.schroeder at kitware.com
> http://www.kitware.com
> (518) 881-4902
>
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