# LOD and closest neighbour with vtk octree
**URL:** https://discourse.vtk.org/t/lod-and-closest-neighbour-with-vtk-octree/7300
**Category:** Support
**Created:** [November 30, 2021, 10:36am UTC](https://discourse.vtk.org/t/lod-and-closest-neighbour-with-vtk-octree/7300 "2021-11-30T10:36:18Z")
**Posts on this page:** 15
**Page:** 1
### Author:  [@Julienchz](https://discourse.vtk.org/u/Julienchz)
#### Post date: [November 30, 2021, 10:36am UTC](https://discourse.vtk.org/t/lod-and-closest-neighbour-with-vtk-octree/7300/1 "2021-11-30T10:36:18Z")
Hello š
I am creating a 3D viewer to display large point cloud, I want to add octree structure to my viewer. This octree must allow me :
- To display the number of level I want
- To find the closest neighbour point
Is there a vtk class that allows me to have this both functionnality in a single octree structure (according to what I found vtk octree is used to find closest neighbour) or should I use potree library ( or create my own octree algorithm and data structure) ?
Thanks for your help
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### Author:  [@mwestphal](https://discourse.vtk.org/u/mwestphal)
#### Post date: [November 30, 2021, 12:46pm UTC](https://discourse.vtk.org/t/lod-and-closest-neighbour-with-vtk-octree/7300/2 "2021-11-30T12:46:22Z")
vtkStaticPointLocator ?
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### Author:  [@Julienchz](https://discourse.vtk.org/u/Julienchz)
#### Post date: [November 30, 2021, 12:49pm UTC](https://discourse.vtk.org/t/lod-and-closest-neighbour-with-vtk-octree/7300/3 "2021-11-30T12:49:15Z")
@mwestphal with vtkStaticPointLocator you can locate a point but I also want to choose de LOD to render to optimize performance and according to the documentation this class does not have such a functionnality or maybe I donāt look at the doc correctly
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### Author:  [@mwestphal](https://discourse.vtk.org/u/mwestphal)
#### Post date: [November 30, 2021, 1:00pm UTC](https://discourse.vtk.org/t/lod-and-closest-neighbour-with-vtk-octree/7300/4 "2021-11-30T13:00:52Z")
Indeed, LOD would need to be performed using a dedicated filter for LOD.
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### Author:  [@Julienchz](https://discourse.vtk.org/u/Julienchz)
#### Post date: [November 30, 2021, 1:12pm UTC](https://discourse.vtk.org/t/lod-and-closest-neighbour-with-vtk-octree/7300/5 "2021-11-30T13:12:15Z")
@mwestphal do you know what kind of filter ? Could I use the same octree with this filter that I create with vtkStaticPointLocator? I am starting to use vtk, itās not easy to see the power of filters
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### Author:  [@mwestphal](https://discourse.vtk.org/u/mwestphal)
#### Post date: [November 30, 2021, 1:17pm UTC](https://discourse.vtk.org/t/lod-and-closest-neighbour-with-vtk-octree/7300/6 "2021-11-30T13:17:26Z")
[https://vtk.org/doc/nightly/html/classvtkDecimatePro.html#details](https://vtk.org/doc/nightly/html/classvtkDecimatePro.html#details)
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### Author:  [@will.schroeder](https://discourse.vtk.org/u/will.schroeder)
#### Post date: [November 30, 2021, 1:19pm UTC](https://discourse.vtk.org/t/lod-and-closest-neighbour-with-vtk-octree/7300/7 "2021-11-30T13:19:09Z")
There are several decimators. Also check out vtkBinnedDecimation (which is similar to what ParaView uses).
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### Author:  [@Julienchz](https://discourse.vtk.org/u/Julienchz)
#### Post date: [November 30, 2021, 1:39pm UTC](https://discourse.vtk.org/t/lod-and-closest-neighbour-with-vtk-octree/7300/8 "2021-11-30T13:39:01Z")
Paraview uses vtkBinnedDecimation as filter to display LOD ? Because Paraview octrees seem to be very efficient. I should maybe go deeper inside the paraview source code to see how octrees are managed
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### Author:  [@mwestphal](https://discourse.vtk.org/u/mwestphal)
#### Post date: [November 30, 2021, 1:39pm UTC](https://discourse.vtk.org/t/lod-and-closest-neighbour-with-vtk-octree/7300/9 "2021-11-30T13:39:47Z")
ParaView use VTKm provided decimator.
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### Author:  [@Julienchz](https://discourse.vtk.org/u/Julienchz)
#### Post date: [November 30, 2021, 2:04pm UTC](https://discourse.vtk.org/t/lod-and-closest-neighbour-with-vtk-octree/7300/10 "2021-11-30T14:04:22Z")
@mwestphal So with a decimator filter, LODMapper and LODActor I should be able to have performance equivalent to paraview octree ?
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### Author:  [@amaclean](https://discourse.vtk.org/u/amaclean)
#### Post date: [November 30, 2021, 9:53pm UTC](https://discourse.vtk.org/t/lod-and-closest-neighbour-with-vtk-octree/7300/11 "2021-11-30T21:53:33Z")
Probable a bit basic for you but some of the octree examples may help e.g. [OctreeVisualize](https://kitware.github.io/vtk-examples/site/Cxx/DataStructures/OctreeVisualize/), there are nine other examples there.
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### Author:  [@Julienchz](https://discourse.vtk.org/u/Julienchz)
#### Post date: [December 1, 2021, 8:13am UTC](https://discourse.vtk.org/t/lod-and-closest-neighbour-with-vtk-octree/7300/12 "2021-12-01T08:13:05Z")
Yes Iāve already seen this example, it displays an octree representation according to the choosen level but you canāt display the corresponding point. I am running through the vtk documentation and examples and honestly for now Iām not totally convinced that using the vtk classes allows me to generate a real octree structure for displaying and finding points.
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### Author:  [@Julienchz](https://discourse.vtk.org/u/Julienchz)
#### Post date: [December 1, 2021, 3:34pm UTC](https://discourse.vtk.org/t/lod-and-closest-neighbour-with-vtk-octree/7300/13 "2021-12-01T15:34:59Z")
When I use vtkBinnedDecimation, I get the error āno data to decimateā, is it posible to apply such a decimator with vtkPoints ?
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### Author:  [@will.schroeder](https://discourse.vtk.org/u/will.schroeder)
#### Post date: [December 1, 2021, 4:11pm UTC](https://discourse.vtk.org/t/lod-and-closest-neighbour-with-vtk-octree/7300/14 "2021-12-01T16:11:32Z")
No, itās a mesh decimation algorithm
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### Author:  [@Julienchz](https://discourse.vtk.org/u/Julienchz)
#### Post date: [December 1, 2021, 4:38pm UTC](https://discourse.vtk.org/t/lod-and-closest-neighbour-with-vtk-octree/7300/15 "2021-12-01T16:38:05Z")
If I want to decimate a pointcloud (vtkpoints), is there some vtk tools to do that or should I do that by my own ?