# Latest

**URL:** https://discourse.vtk.org/latest.md?page=196

[Latest](https://discourse.vtk.org/latest.md) · [Categories](https://discourse.vtk.org/categories.md) · [Tags](https://discourse.vtk.org/tags.md)

**Page:** 197

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## [How to merge two PolyData into one](https://discourse.vtk.org/t/how-to-merge-two-polydata-into-one/4431)

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**Author:** [@siaeleni](https://discourse.vtk.org/u/siaeleni)\
**Replies:** 7\
**Last updated:** [October 19, 2020, 12:29pm UTC](https://discourse.vtk.org/t/how-to-merge-two-polydata-into-one/4431 "2020-10-19T12:29:21Z")

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Hello, I would like to merge two vtkpolydata if it is possible, but I want to know at the end which point comes from which dataset. Also, I want to be sure that BuildLinks() will work and be able to find the correct nei…

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## [Porting surface reconstruction to web](https://discourse.vtk.org/t/porting-surface-reconstruction-to-web/4442)

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**Author:** [@SArbabi](https://discourse.vtk.org/u/SArbabi)\
**Replies:** 0\
**Last updated:** [October 19, 2020, 9:00am UTC](https://discourse.vtk.org/t/porting-surface-reconstruction-to-web/4442 "2020-10-19T09:00:54Z")

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Hi, I’m visualizing a point cloud in browser to user, along with a set of controllers that by interacting with them, point cloud gets updated and visualized again in real time. Now I want to visualize the surface inste…

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## [How to apply a transform/ICPtransform to a volume/dicom forever,and then save as a dicom](https://discourse.vtk.org/t/how-to-apply-a-transform-icptransform-to-a-volume-dicom-forever-and-then-save-as-a-dicom/4438)

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**Author:** [@LiZhenzhuBlog](https://discourse.vtk.org/u/LiZhenzhuBlog)\
**Replies:** 0\
**Last updated:** [October 18, 2020, 1:48am UTC](https://discourse.vtk.org/t/how-to-apply-a-transform-icptransform-to-a-volume-dicom-forever-and-then-save-as-a-dicom/4438 "2020-10-18T01:48:48Z")

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How to apply a transform/ICPtransform to a volume/dicom forever,and then save as a dicom/nrrd.

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## [Cancel rightButtonPress event](https://discourse.vtk.org/t/cancel-rightbuttonpress-event/4429)

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**Author:** [@liyunfei18](https://discourse.vtk.org/u/liyunfei18)\
**Replies:** 4\
**Last updated:** [October 17, 2020, 2:56am UTC](https://discourse.vtk.org/t/cancel-rightbuttonpress-event/4429 "2020-10-17T02:56:57Z")

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I am using CellPicker to achieving picking cells with vtk.js and I want to cancel rightButtonPress event after using renderWindow.getInteractor().onRightButtonPress. I have been searching for a long time and have not …

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## [Very long time to deform FE mesh with Thin-plate Spline Transformation](https://discourse.vtk.org/t/very-long-time-to-deform-fe-mesh-with-thin-plate-spline-transformation/4427)

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**Author:** [@isuruwi](https://discourse.vtk.org/u/isuruwi)\
**Replies:** 2\
**Last updated:** [October 16, 2020, 2:16pm UTC](https://discourse.vtk.org/t/very-long-time-to-deform-fe-mesh-with-thin-plate-spline-transformation/4427 "2020-10-16T14:16:53Z")

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I have created a conformal mesh in gmsh by wrapping a volumetric liver mesh with a box with two physical entities, one is to hold the entire volume and the other is to hold the liver which is inside of the box. When I sa…

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## [vtk python packages](https://discourse.vtk.org/t/vtk-python-packages/4418)

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**Author:** [@Charalambos\_Greg](https://discourse.vtk.org/u/Charalambos_Greg)\
**Replies:** 11\
**Last updated:** [October 16, 2020, 11:55am UTC](https://discourse.vtk.org/t/vtk-python-packages/4418 "2020-10-16T11:55:30Z")

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I have been trying to install python packages for vtk and its modules on windows for several days now and it seems that I am getting something wrong. I install python 3.9 and when i try to install vtk by typing pip insta…

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## [Enabling self-occlusion shadows wrt. Image-based skybox lighting](https://discourse.vtk.org/t/enabling-self-occlusion-shadows-wrt-image-based-skybox-lighting/4358)

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**Author:** [@Chopian](https://discourse.vtk.org/u/Chopian)\
**Replies:** 3\
**Last updated:** [October 16, 2020, 8:20am UTC](https://discourse.vtk.org/t/enabling-self-occlusion-shadows-wrt-image-based-skybox-lighting/4358 "2020-10-16T08:20:06Z")

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I want to illuminate a triangle mesh (from an .stl file) using only imagebased skybox lighting. When rendering an object, it appears that no shadows are cast from self occlusion. Eg. lighting a cylinder from a 45 degree …

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## [Top, Left, Right, Bottom, Back View.](https://discourse.vtk.org/t/top-left-right-bottom-back-view/4426)

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**Author:** [@Seram](https://discourse.vtk.org/u/Seram)\
**Replies:** 4\
**Last updated:** [October 16, 2020, 5:20am UTC](https://discourse.vtk.org/t/top-left-right-bottom-back-view/4426 "2020-10-16T05:20:38Z")

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Hello, ex) Top View ( I programmed the code below to implement CloudCompare Top View. But it looks like a Top View, but I don’t think it’s a perfect Top View. ( It seems to be tilted very slightly. ) Let me know w…

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## [Rendering on multiple GPUs?](https://discourse.vtk.org/t/rendering-on-multiple-gpus/837)

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**Author:** [@wokadeh](https://discourse.vtk.org/u/wokadeh)\
**Replies:** 3\
**Last updated:** [October 16, 2020, 3:18am UTC](https://discourse.vtk.org/t/rendering-on-multiple-gpus/837 "2020-10-16T03:18:37Z")

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Dear community, I haven’t started with VTK yet and I am exploring its advantages. My current question is if it possible to render on multiple GPUs. I have a workstation with two nVidia GPUs and want to use its full powe…

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## [Speeding up vtkCellPicker with vtkCellLocator](https://discourse.vtk.org/t/speeding-up-vtkcellpicker-with-vtkcelllocator/4182)

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**Author:** [@raungst](https://discourse.vtk.org/u/raungst)\
**Replies:** 2\
**Last updated:** [October 15, 2020, 9:41pm UTC](https://discourse.vtk.org/t/speeding-up-vtkcellpicker-with-vtkcelllocator/4182 "2020-10-15T21:41:45Z")

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I’ve been trying to speed up vtkCellPicker with my large data set (1M cells). I’ve followed other examples to add a vtkCellLocator to the vtkCellPicker to improve performance. Unfortunately, I don’t see any improvement w…

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## [SSAO peculiar effect with translucent geometry](https://discourse.vtk.org/t/ssao-peculiar-effect-with-translucent-geometry/4410)

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**Author:** [@fraseyboo](https://discourse.vtk.org/u/fraseyboo)\
**Replies:** 2\
**Last updated:** [October 15, 2020, 8:37pm UTC](https://discourse.vtk.org/t/ssao-peculiar-effect-with-translucent-geometry/4410 "2020-10-15T20:37:56Z")

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So I’m experiencing an issue utilizing the VTK SSAO pass whilst having translucent geometry within a scene. I’ve been utilizing the default renderer until recently but had to switch because as far as I know in order to u…

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## [How to obtain the complete center lines using VMTK?](https://discourse.vtk.org/t/how-to-obtain-the-complete-center-lines-using-vmtk/4425)

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**Author:** [@KaryLiang](https://discourse.vtk.org/u/KaryLiang)\
**Replies:** 1\
**Last updated:** [October 15, 2020, 1:44pm UTC](https://discourse.vtk.org/t/how-to-obtain-the-complete-center-lines-using-vmtk/4425 "2020-10-15T13:44:22Z")

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I’m trying to obtain center lines from airway using VMTK. After dilating the pixels of airway, i got most of the center line, including from the small airway, looks like this: my problem is, why the center lines are …

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## [How to make two volume data fused?](https://discourse.vtk.org/t/how-to-make-two-volume-data-fused/4406)

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**Author:** [@wulicheng](https://discourse.vtk.org/u/wulicheng)\
**Replies:** 4\
**Last updated:** [October 15, 2020, 7:52am UTC](https://discourse.vtk.org/t/how-to-make-two-volume-data-fused/4406 "2020-10-15T07:52:31Z")

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Now I have two or more vtkImageData, And I add the data to two vtkVolumes, Now I want to Fused these two vtkImageDatas or vtkVolumes into one? someone give me a sugisstion! In fact, I want to fused two vtkImageData to…

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## [Unit tests for user code](https://discourse.vtk.org/t/unit-tests-for-user-code/4391)

<div class="topic-metadata">

**Author:** [@seattlewayne](https://discourse.vtk.org/u/seattlewayne)\
**Replies:** 1\
**Last updated:** [October 14, 2020, 7:36pm UTC](https://discourse.vtk.org/t/unit-tests-for-user-code/4391 "2020-10-14T19:36:03Z")

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I have built a webapp that utilizes VTK.js. I have not been able to get unit test coverage for my classes that reference VTK.js code. Karma (which is used in VTK.js) is built for CommonJs modules. It has tools for using …

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## [interactive point cloud generation+surface extraction+visualization.](https://discourse.vtk.org/t/interactive-point-cloud-generation-surface-extraction-visualization/4380)

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**Author:** [@SArbabi](https://discourse.vtk.org/u/SArbabi)\
**Replies:** 3\
**Last updated:** [October 12, 2020, 7:07pm UTC](https://discourse.vtk.org/t/interactive-point-cloud-generation-surface-extraction-visualization/4380 "2020-10-12T19:07:28Z")

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Hi, I want to give the user the ability to work on some parameters that when changed, gets multiplied by a constant matrix of numbers, then out of this multiplication a new point-cloud gets generated, then the surface o…

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## [vtkSmartVolumeMapper sample distance](https://discourse.vtk.org/t/vtksmartvolumemapper-sample-distance/4375)

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**Author:** [@aowen](https://discourse.vtk.org/u/aowen)\
**Replies:** 12\
**Last updated:** [October 14, 2020, 5:48pm UTC](https://discourse.vtk.org/t/vtksmartvolumemapper-sample-distance/4375 "2020-10-14T17:48:17Z")

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I’ve been running into an issue with using the vtkSmartVolumeMapper to visualize datasets that exist in very small ranges. What happens is the opacity changes are very dramatic. If I change the opacity from 100% opaque t…

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## [Library "not found" after building test with CMake on Ubuntu.](https://discourse.vtk.org/t/library-not-found-after-building-test-with-cmake-on-ubuntu/2988)

<div class="topic-metadata">

**Author:** [@cousinitt](https://discourse.vtk.org/u/cousinitt)\
**Replies:** 21\
**Last updated:** [October 14, 2020, 2:04pm UTC](https://discourse.vtk.org/t/library-not-found-after-building-test-with-cmake-on-ubuntu/2988 "2020-10-14T14:04:46Z")

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I built VTK from source (8.2.0) and I am using CMake 3.13. My system is Ubuntu 19.10, with kernel 5.3.0-42-generic. I copied the sphere example into a directory. I did not use the CMakeLists.txt file in the example, b…

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## [VTK 9.0 dll missing with same setup of vtk vtk 8.x](https://discourse.vtk.org/t/vtk-9-0-dll-missing-with-same-setup-of-vtk-vtk-8-x/4409)

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**Author:** [@zandarina](https://discourse.vtk.org/u/zandarina)\
**Replies:** 6\
**Last updated:** [October 14, 2020, 7:02am UTC](https://discourse.vtk.org/t/vtk-9-0-dll-missing-with-same-setup-of-vtk-vtk-8-x/4409 "2020-10-14T07:02:49Z")

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Hello, I have a doubt. With vtk 8.0, I haven’t had to add the dll in the bin directory with shared lib option ticked. With the cmake visual was able to find the dll but I found that in vtk 9.0 I am forced to put all dll…

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## [How to pick a point closest from the mouse cursor?](https://discourse.vtk.org/t/how-to-pick-a-point-closest-from-the-mouse-cursor/4318)

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**Author:** [@Kim\_William](https://discourse.vtk.org/u/Kim_William)\
**Replies:** 10\
**Last updated:** [October 14, 2020, 5:15am UTC](https://discourse.vtk.org/t/how-to-pick-a-point-closest-from-the-mouse-cursor/4318 "2020-10-14T05:15:25Z")

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Hi all. I have a question about pick a point. I have a commercial program that provides a function what if the mouse cursor moving, the closest point is selected. It is useful when I zoom in the point cloud data and c…

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## [How to convert a vtkLineSource into vtkImageData,and render like a line not a Cuboid！](https://discourse.vtk.org/t/how-to-convert-a-vtklinesource-into-vtkimagedata-and-render-like-a-line-not-a-cuboid/4413)

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**Author:** [@wulicheng](https://discourse.vtk.org/u/wulicheng)\
**Replies:** 0\
**Last updated:** [October 14, 2020, 3:58am UTC](https://discourse.vtk.org/t/how-to-convert-a-vtklinesource-into-vtkimagedata-and-render-like-a-line-not-a-cuboid/4413 "2020-10-14T03:58:18Z")

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## [Missing vtkmdiympi\_nompi.dll](https://discourse.vtk.org/t/missing-vtkmdiympi-nompi-dll/3974)

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**Author:** [@McDave17](https://discourse.vtk.org/u/McDave17)\
**Replies:** 2\
**Last updated:** [October 13, 2020, 12:57pm UTC](https://discourse.vtk.org/t/missing-vtkmdiympi-nompi-dll/3974 "2020-10-13T12:57:58Z")

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Hello, since this is quite a different issue then my build issues I wanted to open a new topic for this. When I compile VTK (newest master branch and updated submodule vtkm) with VTK\_GROUP\_ENABLE\_Qt, VTK\_MODULE\_ENABLE\_V…

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## [Troubleshooting one of the examples.](https://discourse.vtk.org/t/troubleshooting-one-of-the-examples/4396)

<div class="topic-metadata">

**Author:** [@Evan\_M](https://discourse.vtk.org/u/Evan_M)\
**Replies:** 8\
**Last updated:** [October 13, 2020, 12:33pm UTC](https://discourse.vtk.org/t/troubleshooting-one-of-the-examples/4396 "2020-10-13T12:33:31Z")

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Hello, I am just trying to get VTK up and running for the first time, so please forgive the simplicity of this question. I have run all the instructions on this page --\> https://vtk.org/Wiki/VTK/Building/Windows , and i…

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## [VTK error : linking shared libraries?](https://discourse.vtk.org/t/vtk-error-linking-shared-libraries/4393)

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**Author:** [@astropiu](https://discourse.vtk.org/u/astropiu)\
**Replies:** 7\
**Last updated:** [October 13, 2020, 10:51am UTC](https://discourse.vtk.org/t/vtk-error-linking-shared-libraries/4393 "2020-10-13T10:51:25Z")

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I just built and installed VTK version 9.0.1 for my ubuntu . I downloaded the cylinder example from the official site and was able to build it fine after fixing the RenderingContextOpenGL2 variable. But when i run the ex…

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## [Bug found in vtkSplineWidget2 when a point is inserted](https://discourse.vtk.org/t/bug-found-in-vtksplinewidget2-when-a-point-is-inserted/2071)

<div class="topic-metadata">

**Author:** [@zandarina](https://discourse.vtk.org/u/zandarina)\
**Replies:** 4\
**Last updated:** [October 13, 2020, 9:17am UTC](https://discourse.vtk.org/t/bug-found-in-vtksplinewidget2-when-a-point-is-inserted/2071 "2020-10-13T09:17:29Z")

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Hi, I wonder if someone has realized that when a point is inserted in a vtkSplineWidget2 (ctrl+right button) from time to time the point is not set in the correct order so the spline is not smooth anymore. I wonder if t…

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## [I want to deallocate volume memory...](https://discourse.vtk.org/t/i-want-to-deallocate-volume-memory/4407)

<div class="topic-metadata">

**Author:** [@wonki](https://discourse.vtk.org/u/wonki)\
**Replies:** 0\
**Last updated:** [October 13, 2020, 8:23am UTC](https://discourse.vtk.org/t/i-want-to-deallocate-volume-memory/4407 "2020-10-13T08:23:02Z")

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I run the program about volume rendering in ios. I set the volume and change the volume by below function that made by me. But I can’t deallocate volume memory… How to do that??? // Not working well... // volume -\> …

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## [vtkGPUVolumeRayCastMapper only consider the last label defined in a mask](https://discourse.vtk.org/t/vtkgpuvolumeraycastmapper-only-consider-the-last-label-defined-in-a-mask/4386)

<div class="topic-metadata">

**Author:** [@zandarina](https://discourse.vtk.org/u/zandarina)\
**Replies:** 5\
**Last updated:** [October 13, 2020, 8:17am UTC](https://discourse.vtk.org/t/vtkgpuvolumeraycastmapper-only-consider-the-last-label-defined-in-a-mask/4386 "2020-10-13T08:17:44Z")

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Hello, I have a doubt I am using vtkGPUVolumeRayCastMapper with a label type mask. And I works if I only define label 1. But I add the label 2 it considers the label 1 as label 2 so the material it takes for both labels…

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## [Multiple threads, each with a self-contained VTK pipeline](https://discourse.vtk.org/t/multiple-threads-each-with-a-self-contained-vtk-pipeline/4360)

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**Author:** [@harold.absalom](https://discourse.vtk.org/u/harold.absalom)\
**Replies:** 1\
**Last updated:** [October 12, 2020, 11:22pm UTC](https://discourse.vtk.org/t/multiple-threads-each-with-a-self-contained-vtk-pipeline/4360 "2020-10-12T23:22:19Z")

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I am trying to write a program where several threads are running, each with their own self-contained vtkRenderWindow, vtkRenderer, pipeline, etc. If I don’t mix any VTK objects between threads, is this possible and/or sa…

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## [VTK crashed while setting LD\_PRELOAD with libGLEW.so](https://discourse.vtk.org/t/vtk-crashed-while-setting-ld-preload-with-libglew-so/4402)

<div class="topic-metadata">

**Author:** [@TooSchoolForCool](https://discourse.vtk.org/u/TooSchoolForCool)\
**Replies:** 1\
**Last updated:** [October 12, 2020, 8:19pm UTC](https://discourse.vtk.org/t/vtk-crashed-while-setting-ld-preload-with-libglew-so/4402 "2020-10-12T20:19:29Z")

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Hi there, My System environment is Ubuntu 16.04, and I installed vtk via pip install vtk If I set export LD\_PRELOAD=$LD\_PRELOAD:/usr/lib/x86\_64-linux-gnu/libGLEW.so then every time when I use vtk in python the progra…

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## [Porting FreeCAD to VTK 9.0](https://discourse.vtk.org/t/porting-freecad-to-vtk-9-0/4404)

<div class="topic-metadata">

**Author:** [@Richard\_Shaw](https://discourse.vtk.org/u/Richard_Shaw)\
**Replies:** 0\
**Last updated:** [October 12, 2020, 8:13pm UTC](https://discourse.vtk.org/t/porting-freecad-to-vtk-9-0/4404 "2020-10-12T20:13:05Z")

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I’m only the Fedora packager for FreeCAD and amateur C++ programmer, but I am asking if we can get some help porting FreeCAD to VTK 9.0 I think we have it down to just a few problem areas. Please see the thread\[1\] in th…

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## [Trying to have the tubeFilter use CellData for coloring instead of point data](https://discourse.vtk.org/t/trying-to-have-the-tubefilter-use-celldata-for-coloring-instead-of-point-data/4365)

<div class="topic-metadata">

**Author:** [@samm-vs](https://discourse.vtk.org/u/samm-vs)\
**Replies:** 5\
**Last updated:** [October 12, 2020, 2:30pm UTC](https://discourse.vtk.org/t/trying-to-have-the-tubefilter-use-celldata-for-coloring-instead-of-point-data/4365 "2020-10-12T14:30:12Z")

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I am trying to use the tube filter but instead of using point data to color the tubes, use cell data instead. However, when I have it use cell data, the color just won’t show up. I am just using this example and building…

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