# Development

**URL:** https://discourse.vtk.org/c/development/7.md?page=1

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

**Page:** 2

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## [VTK modules and dependencies](https://discourse.vtk.org/t/vtk-modules-and-dependencies/16389)

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**Author:** [@nbeck](https://discourse.vtk.org/u/nbeck)\
**Replies:** 3\
**Last updated:** [May 4, 2026, 6:49am UTC](https://discourse.vtk.org/t/vtk-modules-and-dependencies/16389 "2026-05-04T06:49:55Z")

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This is a question about how the modules in VTK are organized. I have a project that uses vtkImageImport and vtkImageExport to handle raw memory data, but doesn’t import or export any files. However, because vtkImageImp…

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## [Support 1D and 2D non linear cells in vtkPolyData](https://discourse.vtk.org/t/support-1d-and-2d-non-linear-cells-in-vtkpolydata/16361)

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**Author:** [@jaswantp](https://discourse.vtk.org/u/jaswantp)\
**Replies:** 10\
**Last updated:** [May 2, 2026, 2:41pm UTC](https://discourse.vtk.org/t/support-1d-and-2d-non-linear-cells-in-vtkpolydata/16361 "2026-05-02T14:41:55Z")

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Non-linear cells are natively used by simulations from the get-go, simply because p-refinement is often better than h-refinement. Higher polynomial orders yield better accuracy more quickly. While users can increase the …

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## [VTK 9.6.1 regression in edges appearance](https://discourse.vtk.org/t/vtk-9-6-1-regression-in-edges-appearance/16393)

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**Author:** [@CharInt0](https://discourse.vtk.org/u/CharInt0)\
**Replies:** 3\
**Last updated:** [April 23, 2026, 3:19pm UTC](https://discourse.vtk.org/t/vtk-9-6-1-regression-in-edges-appearance/16393 "2026-04-23T15:19:49Z")

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After updating the VTK library in my C++ application (from v. 9.4.2 to .9.6.1), the rendering of some Surfaces shows some unexpected edge artifacts. All is compiled in Release mode. This image is with VTK 9.4.2: This…

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## [Active vtkMultiVolume issues closed](https://discourse.vtk.org/t/active-vtkmultivolume-issues-closed/16388)

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**Author:** [@cpinter](https://discourse.vtk.org/u/cpinter)\
**Replies:** 2\
**Last updated:** [April 23, 2026, 8:41am UTC](https://discourse.vtk.org/t/active-vtkmultivolume-issues-closed/16388 "2026-04-23T08:41:35Z")

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Dear maintainers, Recently, two issues were closed that were not actually solved for several years. I indicated this in comments but there was no reaction. https://gitlab.kitware.com/vtk/vtk/-/work\_items/17302 https:/…

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## [vtkExodusIIReader: Potential Memory Bugs](https://discourse.vtk.org/t/vtkexodusiireader-potential-memory-bugs/16382)

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**Author:** [@Landon-Huking](https://discourse.vtk.org/u/Landon-Huking)\
**Replies:** 2\
**Last updated:** [April 21, 2026, 3:39pm UTC](https://discourse.vtk.org/t/vtkexodusiireader-potential-memory-bugs/16382 "2026-04-21T15:39:03Z")

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Intro Hi! I have been fuzzing VTK file readers and have potentially fond some memory bugs in the vtkExodusIIReader module. Fuzzing Setup All fuzzing was done with AFL++ using a from source build of VTK with AFL instrume…

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## [VTK reporting potential vulnerabilities](https://discourse.vtk.org/t/vtk-reporting-potential-vulnerabilities/15796)

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**Author:** [@harrypantazis](https://discourse.vtk.org/u/harrypantazis)\
**Replies:** 3\
**Last updated:** [April 17, 2026, 11:39pm UTC](https://discourse.vtk.org/t/vtk-reporting-potential-vulnerabilities/15796 "2026-04-17T23:39:14Z")

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Greetings, I have been fuzzing an open-source application which depends on VTK (9.5) as part of a security code audit and have identified a series of memory errors for a specific filetype parser in VTK. Which would be …

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## [vtkHyperTreeGridEvaluateCoarse: data race in vtkThreadedTaskQueue produces short output array](https://discourse.vtk.org/t/vtkhypertreegridevaluatecoarse-data-race-in-vtkthreadedtaskqueue-produces-short-output-array/16369)

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**Author:** [@omdaniel](https://discourse.vtk.org/u/omdaniel)\
**Replies:** 8\
**Last updated:** [April 17, 2026, 7:54am UTC](https://discourse.vtk.org/t/vtkhypertreegridevaluatecoarse-data-race-in-vtkthreadedtaskqueue-produces-short-output-array/16369 "2026-04-17T07:54:44Z")

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I am running into an issue of non-deterministic output when using vtkHyperTreeGridEvaluateCourse when I run my vtkhdf with a few hundred time steps, in about 1-5% of the times steps the resulting cell arrays have off by…

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## [VTK WebGPU Roadmap](https://discourse.vtk.org/t/vtk-webgpu-roadmap/13749)

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**Author:** [@jaswantp](https://discourse.vtk.org/u/jaswantp)\
**Replies:** 20\
**Last updated:** [April 14, 2026, 2:59am UTC](https://discourse.vtk.org/t/vtk-webgpu-roadmap/13749 "2026-04-14T02:59:36Z")

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Disclaimer: Please do not confuse the “web” with JavaScript. The goal is to use pure C webgpu header/implementations on desktop AND support web applications through webassembly :slight\_smile: Last year, we added experim…

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## [How to measure 3D rotation smoothness / speed of a vtk 9.3.0 image embedded in a qt 6 application](https://discourse.vtk.org/t/how-to-measure-3d-rotation-smoothness-speed-of-a-vtk-9-3-0-image-embedded-in-a-qt-6-application/16372)

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**Author:** [@ataban](https://discourse.vtk.org/u/ataban)\
**Replies:** 1\
**Last updated:** [April 10, 2026, 1:55pm UTC](https://discourse.vtk.org/t/how-to-measure-3d-rotation-smoothness-speed-of-a-vtk-9-3-0-image-embedded-in-a-qt-6-application/16372 "2026-04-10T13:55:15Z")

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How to measure 3D rotation smoothness / speed of a vtk 9.3.0 image embedded in a qt 6 application with tools like FRAPS. Currently tools like FRAPS and nvidea control panel are working only on laptops for fps display b…

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## [Build Python wheels with SMP tools for runtime backend selection](https://discourse.vtk.org/t/build-python-wheels-with-smp-tools-for-runtime-backend-selection/16268)

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**Author:** [@user27182](https://discourse.vtk.org/u/user27182)\
**Replies:** 20\
**Last updated:** [April 10, 2026, 7:33am UTC](https://discourse.vtk.org/t/build-python-wheels-with-smp-tools-for-runtime-backend-selection/16268 "2026-04-10T07:33:09Z")

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According to the build settings: Users can set: VTK\_SMP\_IMPLEMENTATION\_TYPE (default Sequential): Set which SMPTools will be implemented by default. Must be either Sequential, STDThread, OpenMP or TBB. The backend c…

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## [BackingStore not updated after removing vtkProp](https://discourse.vtk.org/t/backingstore-not-updated-after-removing-vtkprop/16366)

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**Author:** [@mholladay](https://discourse.vtk.org/u/mholladay)\
**Replies:** 0\
**Last updated:** [March 31, 2026, 8:51pm UTC](https://discourse.vtk.org/t/backingstore-not-updated-after-removing-vtkprop/16366 "2026-03-31T20:51:15Z")

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When using a vtkRenderer with BackingStoreOn(), the display does not seem to get updated when a vtkProp is removed from the scene or when its visibility transitions from 1 to 0. It looks like this is probably caused by t…

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## [Problem cancelling vtkStlReader](https://discourse.vtk.org/t/problem-cancelling-vtkstlreader/16362)

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**Author:** [@arey505](https://discourse.vtk.org/u/arey505)\
**Replies:** 6\
**Last updated:** [March 31, 2026, 8:04am UTC](https://discourse.vtk.org/t/problem-cancelling-vtkstlreader/16362 "2026-03-31T08:04:49Z")

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I am running the vtkStlReader in a background thread to load a very large stl file. I would like to allow cancelling during the Update() call execution. I have tried calling the reader’s AbortExecuteOn() method, but t…

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## [Problem offscreen rendering](https://discourse.vtk.org/t/problem-offscreen-rendering/12936)

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**Author:** [@Rafael\_Scatena](https://discourse.vtk.org/u/Rafael_Scatena)\
**Replies:** 1\
**Last updated:** [March 27, 2026, 3:40am UTC](https://discourse.vtk.org/t/problem-offscreen-rendering/12936 "2026-03-27T03:40:36Z")

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Hello, I can’t run my offscreen rendering code. It is just the offscreen rendering example… Thank you. #ifdef ENABLE\_OFFSCREEN\_RENDERING // Setup offscreen rendering vtkNew\<vtkNamedColors\> colors; …

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## [Changes to the VTK array interface: Size(), Resize(), Allocate()](https://discourse.vtk.org/t/changes-to-the-vtk-array-interface-size-resize-allocate/16344)

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**Author:** [@dgobbi](https://discourse.vtk.org/u/dgobbi)\
**Replies:** 2\
**Last updated:** [March 26, 2026, 9:15pm UTC](https://discourse.vtk.org/t/changes-to-the-vtk-array-interface-size-resize-allocate/16344 "2026-03-26T21:15:15Z")

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Deprecation of Size and Resize Methods In the master branch, VTK has deprecated the GetSize() and Resize() methods of vtkAbstractArray, which is the superclass of vtkDataArray. The reason for this is that the behavior…

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## [Volume for QuadHexahedrons incorrect](https://discourse.vtk.org/t/volume-for-quadhexahedrons-incorrect/16358)

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**Author:** [@magicmangoman](https://discourse.vtk.org/u/magicmangoman)\
**Replies:** 0\
**Last updated:** [March 25, 2026, 2:42pm UTC](https://discourse.vtk.org/t/volume-for-quadhexahedrons-incorrect/16358 "2026-03-25T14:42:12Z")

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Incorrect Volume for QuadraticHexahedron ?! Hi, it appears that vtk gives out an incorrect volume for QuadraticHexahedrons, i.e. for the Cell defined in vtkQuadraticHexahedron.h. This is verified by the failure of the f…

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## [New \`vtkCellGrid\` Functionality](https://discourse.vtk.org/t/new-vtkcellgrid-functionality/14640)

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**Author:** [@dcthomp](https://discourse.vtk.org/u/dcthomp)\
**Replies:** 5\
**Last updated:** [March 24, 2026, 2:06pm UTC](https://discourse.vtk.org/t/new-vtkcellgrid-functionality/14640 "2026-03-24T14:06:27Z")

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Hi all, vtkCellGrid and its related source/filter classes have had some significant changes committed recently. These changes are summarized below. They are in VTK master and will be in VTK 9.4.0 (branching October 5th)…

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## [Potential bug in vtkInformationVector::Remove()](https://discourse.vtk.org/t/potential-bug-in-vtkinformationvector-remove/16353)

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**Author:** [@sunjnn](https://discourse.vtk.org/u/sunjnn)\
**Replies:** 1\
**Last updated:** [March 24, 2026, 10:56am UTC](https://discourse.vtk.org/t/potential-bug-in-vtkinformationvector-remove/16353 "2026-03-24T10:56:09Z")

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There appears to be a logic issue in vtkInformationVector::Remove() that causes incorrect behavior when removing information objects from the vector, particularly when the same object appears multiple times. The current…

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## [VTKHDF roadmap](https://discourse.vtk.org/t/vtkhdf-roadmap/13257)

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**Author:** [@lgivord](https://discourse.vtk.org/u/lgivord)\
**Replies:** 26\
**Last updated:** [March 21, 2026, 2:54pm UTC](https://discourse.vtk.org/t/vtkhdf-roadmap/13257 "2026-03-21T14:54:07Z")

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THIS POST IS OUTDATED AND ONLY KEPT FOR HISTORIC PURPOSES Please consult the up to date roadmap here: VTKHDF: Implementation Status - VTK documentation ==================================================================…

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## [VTK 9.6 for Windows 32 and 64 bit and Visual Studio 2026](https://discourse.vtk.org/t/vtk-9-6-for-windows-32-and-64-bit-and-visual-studio-2026/16340)

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**Author:** [@jonasolsson](https://discourse.vtk.org/u/jonasolsson)\
**Replies:** 2\
**Last updated:** [March 19, 2026, 6:14pm UTC](https://discourse.vtk.org/t/vtk-9-6-for-windows-32-and-64-bit-and-visual-studio-2026/16340 "2026-03-19T18:14:04Z")

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I just built VTK 9.6 for both 32 bit and 64 bit with release configuration and Visual Studio 2026. It built without any issues. I have an old project that was using VTK 6.3 and static libraries. The old vtkCommonCore-6…

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## [callback set on vtkWidgetCallbackMapper - vtkCommand::MouseMoveEvent working randomely in vtk 9](https://discourse.vtk.org/t/callback-set-on-vtkwidgetcallbackmapper-vtkcommand-mousemoveevent-working-randomely-in-vtk-9/16342)

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**Author:** [@ataban](https://discourse.vtk.org/u/ataban)\
**Replies:** 1\
**Last updated:** [March 19, 2026, 6:14pm UTC](https://discourse.vtk.org/t/callback-set-on-vtkwidgetcallbackmapper-vtkcommand-mousemoveevent-working-randomely-in-vtk-9/16342 "2026-03-19T18:14:01Z")

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Code snippet ================ -\>CallbackMapper-\>SetCallbackMethod(vtkCommand::MouseMoveEvent, vtkWidgetEvent::Move, this, vtkOrientationBoxMarkerWidget::MoveAction); The callback was working perfectly in vtk 5 but n…

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## [vtk-easy: a nice js-like veneer over vtkjs syntax](https://discourse.vtk.org/t/vtk-easy-a-nice-js-like-veneer-over-vtkjs-syntax/16326)

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**Author:** [@mhalle](https://discourse.vtk.org/u/mhalle)\
**Replies:** 9\
**Last updated:** [March 17, 2026, 3:19am UTC](https://discourse.vtk.org/t/vtk-easy-a-nice-js-like-veneer-over-vtkjs-syntax/16326 "2026-03-17T03:19:35Z")

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Hi there, Ever since the earliest VTK days I’ve had both respect for and aggravation with VTK’s verbose syntax, specifically the getter and setter syntax and the fact that operations aren’t chainable in languages like P…

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## [vtkCellArray: Support offsets/connectivity as vtkDataArray | vtkUnstructuredGrid: Support CellTypes as vtkDataArray](https://discourse.vtk.org/t/vtkcellarray-support-offsets-connectivity-as-vtkdataarray-vtkunstructuredgrid-support-celltypes-as-vtkdataarray/16079)

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**Author:** [@spyridon97](https://discourse.vtk.org/u/spyridon97)\
**Replies:** 13\
**Last updated:** [March 16, 2026, 7:17pm UTC](https://discourse.vtk.org/t/vtkcellarray-support-offsets-connectivity-as-vtkdataarray-vtkunstructuredgrid-support-celltypes-as-vtkdataarray/16079 "2026-03-16T19:17:05Z")

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A large Merge request is about to land in VTK master that changes several core parts of VTK quite a bit. Any feedback would be more than welcome. vtkCellArray: Support offsets/connectivity as vtkDataArray including vtkA…

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## [Issues with the deprecation of vtkImageThreshold](https://discourse.vtk.org/t/issues-with-the-deprecation-of-vtkimagethreshold/16298)

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**Author:** [@amaclean](https://discourse.vtk.org/u/amaclean)\
**Replies:** 7\
**Last updated:** [March 16, 2026, 3:58am UTC](https://discourse.vtk.org/t/issues-with-the-deprecation-of-vtkimagethreshold/16298 "2026-03-16T03:58:12Z")

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The first issue is that vtkImageBinaryThreshold does not seem to be wrapped in Python. I would expect it to be in vtkmodules.vtkImagingCore like the deprecated vtkImageThreshold. The second issue relates to HybridMedian…

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## [Why are the vtkm accelerated filters slower than the native vtk ones?](https://discourse.vtk.org/t/why-are-the-vtkm-accelerated-filters-slower-than-the-native-vtk-ones/16323)

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**Author:** [@Yzwovo](https://discourse.vtk.org/u/Yzwovo)\
**Replies:** 8\
**Last updated:** [March 16, 2026, 2:18am UTC](https://discourse.vtk.org/t/why-are-the-vtkm-accelerated-filters-slower-than-the-native-vtk-ones/16323 "2026-03-16T02:18:33Z")

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Hello everyone, I am testing the acceleration effect of VTK-m and encountered a puzzling issue: the VTKm filter (vtkmContour) takes longer to execute than the native VTK filter (vtkContourFilter), except when I use VTK …

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## [VTK Wedge Cell Types: Fix Point Ordering, Triangulation and Volume Correctness](https://discourse.vtk.org/t/vtk-wedge-cell-types-fix-point-ordering-triangulation-and-volume-correctness/16322)

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**Author:** [@spyridon97](https://discourse.vtk.org/u/spyridon97)\
**Replies:** 4\
**Last updated:** [March 11, 2026, 5:51pm UTC](https://discourse.vtk.org/t/vtk-wedge-cell-types-fix-point-ordering-triangulation-and-volume-correctness/16322 "2026-03-11T17:51:18Z")

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It was brought to our attention by @user27182 in https://gitlab.kitware.com/vtk/vtk/-/issues/19639 that the point ordering implied by the parametric coordinates of vtkWedge, and utilized by its shape functions for interp…

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## [vtkThresholdScalar with empty intervals](https://discourse.vtk.org/t/vtkthresholdscalar-with-empty-intervals/16318)

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**Author:** [@nbeck](https://discourse.vtk.org/u/nbeck)\
**Replies:** 2\
**Last updated:** [March 9, 2026, 8:34am UTC](https://discourse.vtk.org/t/vtkthresholdscalar-with-empty-intervals/16318 "2026-03-09T08:34:38Z")

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Hi, I’ve played around with the new vtkThresholdScalars class and it works nicely. However, I was surprised to see that it can’t be used when no interval is added. Of course in a static setting it doesn’t make sense to …

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## [VTKHDF proposal: Support for Dataset Attributes](https://discourse.vtk.org/t/vtkhdf-proposal-support-for-dataset-attributes/16281)

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**Author:** [@Louis\_Gombert](https://discourse.vtk.org/u/Louis_Gombert)\
**Replies:** 4\
**Last updated:** [March 9, 2026, 7:51am UTC](https://discourse.vtk.org/t/vtkhdf-proposal-support-for-dataset-attributes/16281 "2026-03-09T07:51:59Z")

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VTK supports dataset attributes defined in vtkDataSetAttributes that can be used to mark certain point and cell arrays as “special” arrays, such as Scalars, Normals, Global ids, etc. Currently, the VTKHDF specification …

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## [Bulk issue closing - apologies](https://discourse.vtk.org/t/bulk-issue-closing-apologies/16320)

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**Author:** [@berk.geveci](https://discourse.vtk.org/u/berk.geveci)\
**Replies:** 0\
**Last updated:** [March 6, 2026, 1:58pm UTC](https://discourse.vtk.org/t/bulk-issue-closing-apologies/16320 "2026-03-06T13:58:08Z")

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Hi all, Last night, I started classifying issues on our gitlab issue tracker and got totally carried away and bulk closed the older (\>5 yrs) issues. Since then I was properly put in my place that this was not the right …

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## [Changing vtkAlgorithm::Update() return type from \`void\` to \`bool\`](https://discourse.vtk.org/t/changing-vtkalgorithm-update-return-type-from-void-to-bool/16164)

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**Author:** [@mwestphal](https://discourse.vtk.org/u/mwestphal)\
**Replies:** 25\
**Last updated:** [March 4, 2026, 3:47pm UTC](https://discourse.vtk.org/t/changing-vtkalgorithm-update-return-type-from-void-to-bool/16164 "2026-03-04T15:47:58Z")

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vtkAlgorithm::Update() have been returning void for a very long time and it has bothered me as soon as I started working with VTK. It means we cannot do this: if (!filter-\>Update()) { // error processing } But inste…

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## [Pythonic vtkDataArray and subclasses design](https://discourse.vtk.org/t/pythonic-vtkdataarray-and-subclasses-design/16310)

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**Author:** [@berk.geveci](https://discourse.vtk.org/u/berk.geveci)\
**Replies:** 3\
**Last updated:** [March 2, 2026, 4:49pm UTC](https://discourse.vtk.org/t/pythonic-vtkdataarray-and-subclasses-design/16310 "2026-03-02T16:49:28Z")

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Hi all, I have been working on making various VTK classes pythonic lately. One of the biggies is the vtkDataArray family. There has been several iterations in this direction in the past. Initially, it started with addin…

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