# Latest

**URL:** https://discourse.vtk.org/latest.md?page=180

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

**Page:** 181

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## [VTK segfault - intersectWithLine() on Ubuntu](https://discourse.vtk.org/t/vtk-segfault-intersectwithline-on-ubuntu/5463)

<div class="topic-metadata">

**Author:** [@nantille](https://discourse.vtk.org/u/nantille)\
**Replies:** 8\
**Last updated:** [April 1, 2021, 1:17pm UTC](https://discourse.vtk.org/t/vtk-segfault-intersectwithline-on-ubuntu/5463 "2021-04-01T13:17:34Z")

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When testing a visualiser I developed for neuroscientific data, I narrowed down the reason for abrupt segfault when using VTK. I’ve got a surface mesh and I use the method intersectWithLine to find intersections with a …

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## [VTK Lights](https://discourse.vtk.org/t/vtk-lights/5479)

<div class="topic-metadata">

**Author:** [@Frank\_Gao](https://discourse.vtk.org/u/Frank_Gao)\
**Replies:** 0\
**Last updated:** [April 1, 2021, 1:13am UTC](https://discourse.vtk.org/t/vtk-lights/5479 "2021-04-01T01:13:50Z")

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Dear VTK experts, I am wondering how many lights we can add to a renderer. I am add bunch of lights, but quickly VTK 9 crashed with message that stack was corrupted in light color code, or somewhere else in vtkLight con…

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## [Java build questions](https://discourse.vtk.org/t/java-build-questions/5462)

<div class="topic-metadata">

**Author:** [@Gilthalas](https://discourse.vtk.org/u/Gilthalas)\
**Replies:** 9\
**Last updated:** [March 31, 2021, 10:14pm UTC](https://discourse.vtk.org/t/java-build-questions/5462 "2021-03-31T22:14:10Z")

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Hi all - happy to say we are having great success building and using VTK 9 in our upgraded tool. We did have a few questions related to the overall Java build process though. First, when the jnilibs are built, they e…

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## [Is Gitlab misbehaving?](https://discourse.vtk.org/t/is-gitlab-misbehaving/5473)

<div class="topic-metadata">

**Author:** [@toddy](https://discourse.vtk.org/u/toddy)\
**Replies:** 5\
**Last updated:** [March 31, 2021, 12:56pm UTC](https://discourse.vtk.org/t/is-gitlab-misbehaving/5473 "2021-03-31T12:56:20Z")

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I can no longer initiate a merge request from my VTK fork. Has something been changed in Gitlab webview?

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## [vtk render unstructured grid and set active camera](https://discourse.vtk.org/t/vtk-render-unstructured-grid-and-set-active-camera/336)

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**Author:** [@francisco\_munoz](https://discourse.vtk.org/u/francisco_munoz)\
**Replies:** 3\
**Last updated:** [March 31, 2021, 11:56am UTC](https://discourse.vtk.org/t/vtk-render-unstructured-grid-and-set-active-camera/336 "2021-03-31T11:56:04Z")

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hi all, i’m trying to do a render of a unstructured grid by setting the camera before interactor. When i render just the unstructured grid alll works fine but when i try to set a custom camera at a given possition it gi…

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## [custom shader uniform in vtk802](https://discourse.vtk.org/t/custom-shader-uniform-in-vtk802/5472)

<div class="topic-metadata">

**Author:** [@beijihuohu](https://discourse.vtk.org/u/beijihuohu)\
**Replies:** 0\
**Last updated:** [March 30, 2021, 10:59pm UTC](https://discourse.vtk.org/t/custom-shader-uniform-in-vtk802/5472 "2021-03-30T22:59:36Z")

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I am using VTK8.2 version. I want to generate simulation animation by updating the shader uniform variables in the graphical interface. However, all the examples use vtkCommand as the basis for updating control. I can on…

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## [picking 1 cube out of many in an actor](https://discourse.vtk.org/t/picking-1-cube-out-of-many-in-an-actor/5470)

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**Author:** [@unclejunior](https://discourse.vtk.org/u/unclejunior)\
**Replies:** 0\
**Last updated:** [March 30, 2021, 10:22pm UTC](https://discourse.vtk.org/t/picking-1-cube-out-of-many-in-an-actor/5470 "2021-03-30T22:22:21Z")

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Hi, I have 1 actor with 100s of cubes (just a starter project). I create the cubes like this: // create points int bias=0; for (const QRect & rect : layer-\>rects()) { QRectF r = rect; points-\>InsertNextPoint(r.…

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## [Qt widgets over the QVTKWidget in Python: no transparency](https://discourse.vtk.org/t/qt-widgets-over-the-qvtkwidget-in-python-no-transparency/5465)

<div class="topic-metadata">

**Author:** [@jean](https://discourse.vtk.org/u/jean)\
**Replies:** 3\
**Last updated:** [March 30, 2021, 7:20pm UTC](https://discourse.vtk.org/t/qt-widgets-over-the-qvtkwidget-in-python-no-transparency/5465 "2021-03-30T19:20:21Z")

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Hi, I can put Qt widgets over the VTK widget in Python, but a few stange things happen when I do. Transparency doesn’t work. The color changes slowly when moving the mouse cursor over the button and reset only when re…

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## [Paraview is not saving stl file with SaveData](https://discourse.vtk.org/t/paraview-is-not-saving-stl-file-with-savedata/5445)

<div class="topic-metadata">

**Author:** [@rasunag27](https://discourse.vtk.org/u/rasunag27)\
**Replies:** 4\
**Last updated:** [March 30, 2021, 7:19am UTC](https://discourse.vtk.org/t/paraview-is-not-saving-stl-file-with-savedata/5445 "2021-03-30T07:19:37Z")

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Dear All, I used one stl file to split the stl using Paraview. I traced the method using python trace in paraview. Now, I used the code in python to run it. It runs perfectly, but it does not save the splitted mesh as …

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## [Compiling VTK with OSPRay + Java wrappers enabled](https://discourse.vtk.org/t/compiling-vtk-with-ospray-java-wrappers-enabled/5461)

<div class="topic-metadata">

**Author:** [@thegbiv](https://discourse.vtk.org/u/thegbiv)\
**Replies:** 5\
**Last updated:** [March 30, 2021, 4:36am UTC](https://discourse.vtk.org/t/compiling-vtk-with-ospray-java-wrappers-enabled/5461 "2021-03-30T04:36:28Z")

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Hello, After a long hiatus, I’ve recently started picking up VTK, and WOW, so much progress and new features to play around with. Kudos to all involved! On to the question… I have been evaluating language support of v…

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## [visualization of fitted thin plate spline from vtkThinPlateSplineTransform](https://discourse.vtk.org/t/visualization-of-fitted-thin-plate-spline-from-vtkthinplatesplinetransform/5460)

<div class="topic-metadata">

**Author:** [@Bjorn\_Hansen](https://discourse.vtk.org/u/Bjorn_Hansen)\
**Replies:** 2\
**Last updated:** [March 29, 2021, 2:52pm UTC](https://discourse.vtk.org/t/visualization-of-fitted-thin-plate-spline-from-vtkthinplatesplinetransform/5460 "2021-03-29T14:52:22Z")

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Hello, I’m currently using the vtkThinPlateSplineTransform to do data augmentation on a mesh of a heart in Python. I would like to visualize the Thin Plate Spline i have fitted to a set of source and target points such t…

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## [Custom scale of a volume](https://discourse.vtk.org/t/custom-scale-of-a-volume/5458)

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**Author:** [@Luis\_Carlos\_Carneiro](https://discourse.vtk.org/u/Luis_Carlos_Carneiro)\
**Replies:** 1\
**Last updated:** [March 29, 2021, 12:22pm UTC](https://discourse.vtk.org/t/custom-scale-of-a-volume/5458 "2021-03-29T12:22:47Z")

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Dear All, Are there some function in VTK that does a dynamic scale of a volume (structured image)? The volume must be scaled not equally but obeying to a scale function that may have first, second derivatives. Or doing…

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## [it takes long time for the iso-surface extraction at first step](https://discourse.vtk.org/t/it-takes-long-time-for-the-iso-surface-extraction-at-first-step/5456)

<div class="topic-metadata">

**Author:** [@1116](https://discourse.vtk.org/u/1116)\
**Replies:** 7\
**Last updated:** [March 29, 2021, 12:12pm UTC](https://discourse.vtk.org/t/it-takes-long-time-for-the-iso-surface-extraction-at-first-step/5456 "2021-03-29T12:12:54Z")

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For my project, the tightly coupled in-situ analytics process the data generated by the simulation at each iteration. The analytics code is just the iso surface extraction based on VTK. I found that the first step of the…

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## [Particle Tracking](https://discourse.vtk.org/t/particle-tracking/4466)

<div class="topic-metadata">

**Author:** [@jbensabat](https://discourse.vtk.org/u/jbensabat)\
**Replies:** 2\
**Last updated:** [March 29, 2021, 11:10am UTC](https://discourse.vtk.org/t/particle-tracking/4466 "2021-03-29T11:10:16Z")

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Hello We are trying to visualize pathlines using particle tracking (vtkParticleTracer) with an unstructured grid there is one example TestParticleTracers, which works on a regular grid. We used the sample example adap…

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## [How to change the property of the vtkBoxWidget2?](https://discourse.vtk.org/t/how-to-change-the-property-of-the-vtkboxwidget2/5457)

<div class="topic-metadata">

**Author:** [@Kim\_William](https://discourse.vtk.org/u/Kim_William)\
**Replies:** 0\
**Last updated:** [March 29, 2021, 8:39am UTC](https://discourse.vtk.org/t/how-to-change-the-property-of-the-vtkboxwidget2/5457 "2021-03-29T08:39:47Z")

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Hi all. I have a question about the vtkBoxWidget2. I’m trying to change the color and thickness of the line of the vtkBoxWidget2. Is it possible to change the property of the vtkBoxWidget2? Could you please give me…

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## [Python VTK example link broken](https://discourse.vtk.org/t/python-vtk-example-link-broken/5453)

<div class="topic-metadata">

**Author:** [@Sh4zKh4n](https://discourse.vtk.org/u/Sh4zKh4n)\
**Replies:** 1\
**Last updated:** [March 29, 2021, 8:05am UTC](https://discourse.vtk.org/t/python-vtk-example-link-broken/5453 "2021-03-29T08:05:31Z")

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Ive been trying to find where the python examples folder is to no avail. The link in the docs goes to no where and if I have a poke through the github it’s missing. Any advice for me where I could find some examples of…

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## [Multiple scalars color mapping](https://discourse.vtk.org/t/multiple-scalars-color-mapping/5403)

<div class="topic-metadata">

**Author:** [@liyunfei18](https://discourse.vtk.org/u/liyunfei18)\
**Replies:** 2\
**Last updated:** [March 29, 2021, 2:17am UTC](https://discourse.vtk.org/t/multiple-scalars-color-mapping/5403 "2021-03-29T02:17:00Z")

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Hello, I want to use VolumeController to color-map the attributes in the PointData in the vti file. I have tried only one Scalar, and it works very well. I now want to include two Scalars in a PointData so that I can sel…

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## [Emissive actor light up other actor with PBR?](https://discourse.vtk.org/t/emissive-actor-light-up-other-actor-with-pbr/5415)

<div class="topic-metadata">

**Author:** [@estan](https://discourse.vtk.org/u/estan)\
**Replies:** 4\
**Last updated:** [March 27, 2021, 10:18am UTC](https://discourse.vtk.org/t/emissive-actor-light-up-other-actor-with-pbr/5415 "2021-03-27T10:18:39Z")

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Hello, Consider this example: import vtk cubeSource = vtk.vtkCubeSource() cubeMapper = vtk.vtkPolyDataMapper() cubeMapper.SetInputConnection(cubeSource.GetOutputPort()) emissiveSource = vtk.vtkImageCanvasSource2D() …

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## [Select closed volume](https://discourse.vtk.org/t/select-closed-volume/5394)

<div class="topic-metadata">

**Author:** [@Luis\_Carlos\_Carneiro](https://discourse.vtk.org/u/Luis_Carlos_Carneiro)\
**Replies:** 5\
**Last updated:** [March 26, 2021, 5:51pm UTC](https://discourse.vtk.org/t/select-closed-volume/5394 "2021-03-26T17:51:15Z")

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Dear All, If I have a single volume (in VTK terms) formed by several closed “volumes”. How I select the points of one of those “volumes” and for example change the color of it? Perhaps, selecting one of the points of t…

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## [Create Canvas Object For 2D Actors](https://discourse.vtk.org/t/create-canvas-object-for-2d-actors/5449)

<div class="topic-metadata">

**Author:** [@bigvalthoss](https://discourse.vtk.org/u/bigvalthoss)\
**Replies:** 0\
**Last updated:** [March 26, 2021, 5:31pm UTC](https://discourse.vtk.org/t/create-canvas-object-for-2d-actors/5449 "2021-03-26T17:31:43Z")

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Hello! I’m new here and was wondering if there is such a thing as a canvas object for vtk so that you can add text/annotations into VR. Note: I’m working in 3Slicer

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## [Rendering time on structured grid](https://discourse.vtk.org/t/rendering-time-on-structured-grid/5446)

<div class="topic-metadata">

**Author:** [@Guillaume\_Gillet](https://discourse.vtk.org/u/Guillaume_Gillet)\
**Replies:** 0\
**Last updated:** [March 26, 2021, 8:36am UTC](https://discourse.vtk.org/t/rendering-time-on-structured-grid/5446 "2021-03-26T08:36:00Z")

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Hello, so i’m using VtkStructuredGrid to render 3D grids and i need to make rendering speed tests to compare vtk with another tool, but i saw after a few tests that when i blanck a part of the cells like i need to do wit…

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## [vtkDistancePolyDataFilter not working with contours?](https://discourse.vtk.org/t/vtkdistancepolydatafilter-not-working-with-contours/5437)

<div class="topic-metadata">

**Author:** [@Ingmar](https://discourse.vtk.org/u/Ingmar)\
**Replies:** 1\
**Last updated:** [March 25, 2021, 1:40pm UTC](https://discourse.vtk.org/t/vtkdistancepolydatafilter-not-working-with-contours/5437 "2021-03-25T13:40:17Z")

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Dear VTK experts, I am trying to use a vtkDistancePolyDataFilter out of python (using vtk==8.1.2 pkg). This seems to work fine for triangle meshes. reader1 = vtk.vtkPolyDataReader() reader1.SetFileName('E:/temp/mes…

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## [extract the coordinates of the point on the slice？](https://discourse.vtk.org/t/extract-the-coordinates-of-the-point-on-the-slice/5427)

<div class="topic-metadata">

**Author:** [@zrxiaojie](https://discourse.vtk.org/u/zrxiaojie)\
**Replies:** 4\
**Last updated:** [March 25, 2021, 2:47am UTC](https://discourse.vtk.org/t/extract-the-coordinates-of-the-point-on-the-slice/5427 "2021-03-25T02:47:04Z")

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Hi, about the VTK.js, I want to ask you about how can I extract the coordinates of the point on the slice？ I successfully extracted the coordinates from a .stl file with the cellPicker/pointPicker, but no matter how I t…

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## [Slicer to Magic Leap Integration](https://discourse.vtk.org/t/slicer-to-magic-leap-integration/5434)

<div class="topic-metadata">

**Author:** [@cshreyas](https://discourse.vtk.org/u/cshreyas)\
**Replies:** 0\
**Last updated:** [March 24, 2021, 6:03pm UTC](https://discourse.vtk.org/t/slicer-to-magic-leap-integration/5434 "2021-03-24T18:03:14Z")

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Hello, I am exploring ways to render Slicer 3D in Magic Leap and make them interactive both ways. Looks like OpenXR integration with Slicer seems to one possible option as per the discuss below. Can you please let m…

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## [Fitting stl file on 2D image](https://discourse.vtk.org/t/fitting-stl-file-on-2d-image/5430)

<div class="topic-metadata">

**Author:** [@Amir\_Hossein\_Zeydi](https://discourse.vtk.org/u/Amir_Hossein_Zeydi)\
**Replies:** 0\
**Last updated:** [March 23, 2021, 7:08pm UTC](https://discourse.vtk.org/t/fitting-stl-file-on-2d-image/5430 "2021-03-23T19:08:37Z")

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I used the code below and I wanted to match a 3D stl on an image: both files are same size but when you open them in two renderer layers they dont match, I tried using pixel sizing to scale but it didnt work either. …

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## [Building dicom](https://discourse.vtk.org/t/building-dicom/5420)

<div class="topic-metadata">

**Author:** [@djduke](https://discourse.vtk.org/u/djduke)\
**Replies:** 7\
**Last updated:** [March 23, 2021, 6:42pm UTC](https://discourse.vtk.org/t/building-dicom/5420 "2021-03-23T18:42:39Z")

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I’ve just tried building the vtk-dicom library from David Gobbi. I have VTK freshly built from git sources, configured with shared-objects on and wrap-python on \[using Python 3\]. Building the DICOM library is fine ho…

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## [Window width - window level do not change in Reslice Cursor Widget example](https://discourse.vtk.org/t/window-width-window-level-do-not-change-in-reslice-cursor-widget-example/5390)

<div class="topic-metadata">

**Author:** [@ronzim](https://discourse.vtk.org/u/ronzim)\
**Replies:** 3\
**Last updated:** [March 23, 2021, 4:31pm UTC](https://discourse.vtk.org/t/window-width-window-level-do-not-change-in-reslice-cursor-widget-example/5390 "2021-03-23T16:31:08Z")

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In the Reslice Cursor Widget example (https://kitware.github.io/vtk-js/examples/ResliceCursorWidget.html), I can see a vtkInteractorStyleImage in the code, but no ww / wl change happen if I drag on the slice. I modified …

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## [Change vtkDistanceWidget handles radius](https://discourse.vtk.org/t/change-vtkdistancewidget-handles-radius/5428)

<div class="topic-metadata">

**Author:** [@ronzim](https://discourse.vtk.org/u/ronzim)\
**Replies:** 4\
**Last updated:** [March 23, 2021, 4:29pm UTC](https://discourse.vtk.org/t/change-vtkdistancewidget-handles-radius/5428 "2021-03-23T16:29:47Z")

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Hi, I have a vtkDistanceWidget in a vtk scene, but handles are so small you can’t interact with them. I searched for a “setRadius” method and I found it in the SphereHandleRepresentation, but it’s not clear to me how to …

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## [Help with TBB "warning: definition of implicit copy ctor"](https://discourse.vtk.org/t/help-with-tbb-warning-definition-of-implicit-copy-ctor/4738)

<div class="topic-metadata">

**Author:** [@seanm](https://discourse.vtk.org/u/seanm)\
**Replies:** 4\
**Last updated:** [March 23, 2021, 2:37pm UTC](https://discourse.vtk.org/t/help-with-tbb-warning-definition-of-implicit-copy-ctor/4738 "2021-03-23T14:37:33Z")

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Hi all, Could one of you C++ wizards help with some TBB-related clang warnings on cdash: https://open.cdash.org/viewBuildError.php?type=1&buildid=6899833 Common/Core/vtkSMPToolsInternal.h:43:8: warning: definition of …

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## [Write to vtkImageData using parallel threads](https://discourse.vtk.org/t/write-to-vtkimagedata-using-parallel-threads/5423)

<div class="topic-metadata">

**Author:** [@janhavi\_deshpande](https://discourse.vtk.org/u/janhavi_deshpande)\
**Replies:** 1\
**Last updated:** [March 23, 2021, 11:00am UTC](https://discourse.vtk.org/t/write-to-vtkimagedata-using-parallel-threads/5423 "2021-03-23T11:00:13Z")

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Hello, I am working in C# and I am currently using setScalarComponentFromDouble function of vtkImageData to set values to ImageData grid. This function is not thread-safe. I have also tried getting image pointer through…

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