# Development

**URL:** https://discourse.vtk.org/c/development/7.md?page=2

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

**Page:** 3

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## [Yet more simple python API](https://discourse.vtk.org/t/yet-more-simple-python-api/16279)

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**Author:** [@berk.geveci](https://discourse.vtk.org/u/berk.geveci)\
**Replies:** 12\
**Last updated:** [March 2, 2026, 10:33am UTC](https://discourse.vtk.org/t/yet-more-simple-python-api/16279 "2026-03-02T10:33:43Z")

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Hi folks, Over this weekend, I prototyped another layer of simple python interface that is a lot closer to pyvista and vedo. Here is a description: The functional and postfix part are super easy to implement and main…

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## [legacy file format: data type and version](https://discourse.vtk.org/t/legacy-file-format-data-type-and-version/16299)

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**Author:** [@MarDiehl](https://discourse.vtk.org/u/MarDiehl)\
**Replies:** 6\
**Last updated:** [March 2, 2026, 9:27am UTC](https://discourse.vtk.org/t/legacy-file-format-data-type-and-version/16299 "2026-03-02T09:27:59Z")

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VTK 9.6.0 has a weird change behavior when it comes to the legacy file format: The data type for OFFSETS and CONNECTIVITY of POLYDATA is vtktypeint64 after creation (using the Python bindings) but changes to long when sa…

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## [Clarification about temporal MB or PDC VTKHDF datasets](https://discourse.vtk.org/t/clarification-about-temporal-mb-or-pdc-vtkhdf-datasets/16305)

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**Author:** [@nncarlson](https://discourse.vtk.org/u/nncarlson)\
**Replies:** 3\
**Last updated:** [February 26, 2026, 9:15am UTC](https://discourse.vtk.org/t/clarification-about-temporal-mb-or-pdc-vtkhdf-datasets/16305 "2026-02-26T09:15:59Z")

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I had been operating under the assumption that in a MB or PDC VTKHDF dataset some blocks could be temporal and others not (without a Steps group). However, I’m getting import errors (with MB) from paraview. Is it requir…

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## [How to properly override GetFiniteValue in our vtkGenericDataArray\<Derived, T\> class](https://discourse.vtk.org/t/how-to-properly-override-getfinitevalue-in-our-vtkgenericdataarray-derived-t-class/16283)

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**Author:** [@Michael\_Jackson](https://discourse.vtk.org/u/Michael_Jackson)\
**Replies:** 9\
**Last updated:** [February 25, 2026, 7:48pm UTC](https://discourse.vtk.org/t/how-to-properly-override-getfinitevalue-in-our-vtkgenericdataarray-derived-t-class/16283 "2026-02-25T19:48:32Z")

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In our application we have implemented a wrapper class using the vtkGenericDataArray\<DerivedType, T\> class. Our class is called CV::Array. Generally things are working fine but as I start to profile our code to see what …

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## [vtkHDF: Add support for polyhedron cells](https://discourse.vtk.org/t/vtkhdf-add-support-for-polyhedron-cells/13089)

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**Author:** [@MicK7](https://discourse.vtk.org/u/MicK7)\
**Replies:** 42\
**Last updated:** [February 24, 2026, 8:57pm UTC](https://discourse.vtk.org/t/vtkhdf-add-support-for-polyhedron-cells/13089 "2026-02-24T20:57:11Z")

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The idea would be to add support for polyhedral cell in a partition of unstructured grid stored in vtkHDF The partition sizing for polyhedral cells would required defining the following variables: NumberOfFaces Number…

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## [Support for RectilinearGrids and StructuredGrids in VTKHDF file format](https://discourse.vtk.org/t/support-for-rectilineargrids-and-structuredgrids-in-vtkhdf-file-format/14283)

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**Author:** [@jpmorr](https://discourse.vtk.org/u/jpmorr)\
**Replies:** 7\
**Last updated:** [February 23, 2026, 1:02pm UTC](https://discourse.vtk.org/t/support-for-rectilineargrids-and-structuredgrids-in-vtkhdf-file-format/14283 "2026-02-23T13:02:06Z")

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Hi, I’m interested in using RectilinearGrids and StructuredGrids in the VTKHDF format. Since these formats are not currently supported or on the roadmap, I’ve taken a few minutes to translate some simple .vtr and .vts f…

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## [QVTK widget is showing slowness in performance when built with vtk 9.3.0 and interacted through mouse/touch/gesture](https://discourse.vtk.org/t/qvtk-widget-is-showing-slowness-in-performance-when-built-with-vtk-9-3-0-and-interacted-through-mouse-touch-gesture/16228)

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**Author:** [@ataban](https://discourse.vtk.org/u/ataban)\
**Replies:** 3\
**Last updated:** [February 16, 2026, 2:24pm UTC](https://discourse.vtk.org/t/qvtk-widget-is-showing-slowness-in-performance-when-built-with-vtk-9-3-0-and-interacted-through-mouse-touch-gesture/16228 "2026-02-16T14:24:01Z")

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VTK 5 version shows a very smooth version of mouse move operations of qvtk widgets containing vtk images including large image slices including in 3D mode. In comparison vtk 9.3 shows comparatively slow performance of t…

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## [tri-plane 2D view of a 3D volume](https://discourse.vtk.org/t/tri-plane-2d-view-of-a-3d-volume/16287)

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**Author:** [@Limz90](https://discourse.vtk.org/u/Limz90)\
**Replies:** 2\
**Last updated:** [February 13, 2026, 7:44am UTC](https://discourse.vtk.org/t/tri-plane-2d-view-of-a-3d-volume/16287 "2026-02-13T07:44:40Z")

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Hi, I am looking for the way (VTK classes to use for 2D view) of doing this (image below), using 4 different renderer windows. Thanks,

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## [How to get the max 3D Texture size from a vtkSmartVolumeMapper](https://discourse.vtk.org/t/how-to-get-the-max-3d-texture-size-from-a-vtksmartvolumemapper/16289)

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**Author:** [@Michael\_Jackson](https://discourse.vtk.org/u/Michael_Jackson)\
**Replies:** 0\
**Last updated:** [February 12, 2026, 5:45pm UTC](https://discourse.vtk.org/t/how-to-get-the-max-3d-texture-size-from-a-vtksmartvolumemapper/16289 "2026-02-12T17:45:16Z")

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Hello, When trying to volume render a data set that is 2300 x 2300 x 750 I am getting the following error: ERROR: OpenGL MAX\_3D\_TEXTURE\_SIZE is 2048 2026-02-12 12:39:14.555 ( 93.864s) \[ 4F6000E\] vtkVolumeTex…

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## [vtk python doesn't support get key PgUp/PgDn](https://discourse.vtk.org/t/vtk-python-doesnt-support-get-key-pgup-pgdn/16284)

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**Author:** [@Nam\_Le\_Hoang](https://discourse.vtk.org/u/Nam_Le_Hoang)\
**Replies:** 2\
**Last updated:** [February 12, 2026, 6:38am UTC](https://discourse.vtk.org/t/vtk-python-doesnt-support-get-key-pgup-pgdn/16284 "2026-02-12T06:38:05Z")

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Hi, I’m using \`vtk==9.5.0\` with python in PySide2. Below is my simple script that I try to catch user key press and do works. But when I type PgUp PgDn the GetKeySym return None . Just wanna know if vtk doesn’t support i…

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## [Remove/Deprecate certain array types](https://discourse.vtk.org/t/remove-deprecate-certain-array-types/16267)

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**Author:** [@spyridon97](https://discourse.vtk.org/u/spyridon97)\
**Replies:** 5\
**Last updated:** [February 11, 2026, 10:05pm UTC](https://discourse.vtk.org/t/remove-deprecate-certain-array-types/16267 "2026-02-11T22:05:31Z")

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Upon working a lot on VTK arrays, i am trying to understand whether we need certain array types. The arrays in question are (read/write) vtkScaledSOADataArrayTemplate (0 VTK filter usages), (read only) vtkCompositeArr…

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## [VTK json](https://discourse.vtk.org/t/vtk-json/16282)

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**Author:** [@Francois\_Merle](https://discourse.vtk.org/u/Francois_Merle)\
**Replies:** 2\
**Last updated:** [February 11, 2026, 10:37am UTC](https://discourse.vtk.org/t/vtk-json/16282 "2026-02-11T10:37:00Z")

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Hello, I am using VTK together with the Drogon C++ web framework. Drogon depends on the system jsoncpp library, while VTK ships its own vendored copy of jsoncpp under vtkjsoncpp (namespace vtkJson). When both librari…

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## [Adding support for opening \*any\* archived single file](https://discourse.vtk.org/t/adding-support-for-opening-any-archived-single-file/16254)

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**Author:** [@mwestphal](https://discourse.vtk.org/u/mwestphal)\
**Replies:** 11\
**Last updated:** [February 10, 2026, 10:58am UTC](https://discourse.vtk.org/t/adding-support-for-opening-any-archived-single-file/16254 "2026-02-10T10:58:54Z")

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Design: Some time ago, I shared a potential design to read archived file in ParaView discourse. Well, this idea never went very far as it required a complex implementation in a third party that only partially existed a…

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## [Slow Rendering of large 2D Image on MacOS, but not Linux or Windows](https://discourse.vtk.org/t/slow-rendering-of-large-2d-image-on-macos-but-not-linux-or-windows/16277)

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**Author:** [@Michael\_Jackson](https://discourse.vtk.org/u/Michael_Jackson)\
**Replies:** 6\
**Last updated:** [February 9, 2026, 10:00pm UTC](https://discourse.vtk.org/t/slow-rendering-of-large-2d-image-on-macos-but-not-linux-or-windows/16277 "2026-02-09T22:00:08Z")

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Hello, We have an existing application that uses VTK 9.5.2 for our 3D visualization. We have noticed that when we load large 2D images (23,500 x 23,500 pixels) that the interaction rendering speed on MacOS is about 3~4 …

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## [Build error: VTK 9.6.0 rc3, vtkResourceStream.cxx line79, std::min, MSVS 14.44/x86/Debug](https://discourse.vtk.org/t/build-error-vtk-9-6-0-rc3-vtkresourcestream-cxx-line79-std-min-msvs-14-44-x86-debug/16280)

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**Author:** [@francek](https://discourse.vtk.org/u/francek)\
**Replies:** 7\
**Last updated:** [February 9, 2026, 10:18am UTC](https://discourse.vtk.org/t/build-error-vtk-9-6-0-rc3-vtkresourcestream-cxx-line79-std-min-msvs-14-44-x86-debug/16280 "2026-02-09T10:18:12Z")

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Hi, I tried to build VTK 9.6.0 rc3 for Win32/x86 and Debug target, but the build failed. In vtkResourceStream.cxx, std::min is called with parameters of different types. 260208\_vtk\_9.6.0.rc3\\IO\\Core\\vtkResourceStre…

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## [OpenFOAMReader precision hardcoded to 32-bit](https://discourse.vtk.org/t/openfoamreader-precision-hardcoded-to-32-bit/16263)

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**Author:** [@gnikit](https://discourse.vtk.org/u/gnikit)\
**Replies:** 12\
**Last updated:** [February 4, 2026, 9:45pm UTC](https://discourse.vtk.org/t/openfoamreader-precision-hardcoded-to-32-bit/16263 "2026-02-04T21:45:18Z")

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Hey guys, I noticed that the OpenFOAM reader in VTK always reads mesh and field data as 32-bit. I had a look at the vtkOpenFOAMReader.cxx file and it appears to that the conversion to 32-bit is hardcoded. Fields (Scala…

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## [VTK on conan centre](https://discourse.vtk.org/t/vtk-on-conan-centre/16112)

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**Author:** [@gnikit](https://discourse.vtk.org/u/gnikit)\
**Replies:** 8\
**Last updated:** [February 2, 2026, 2:52pm UTC](https://discourse.vtk.org/t/vtk-on-conan-centre/16112 "2026-02-02T14:52:57Z")

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Hey guys, I wanted to ask if Kitware/VTK would consider/has considered adding a VTK recipe on Conan 2.0: C and C++ Open Source Package Manager . There might be good reasons as to why you haven’t done so already, but none…

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## [Possible 9.6.0 regression with environment texture rendering](https://discourse.vtk.org/t/possible-9-6-0-regression-with-environment-texture-rendering/16247)

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**Author:** [@user27182](https://discourse.vtk.org/u/user27182)\
**Replies:** 8\
**Last updated:** [February 1, 2026, 3:47pm UTC](https://discourse.vtk.org/t/possible-9-6-0-regression-with-environment-texture-rendering/16247 "2026-02-01T15:47:54Z")

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The following script loads a cube map as a skybox environment texture and plots a metallic sphere with PBR. env\_texture.py (2.8 KB) cubemap\_park.zip (592.7 KB) Usage: download script and unzip cubemap files. Then run …

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## [only depending on vtk, use vtkmfcwindow，and setparent(HWND hwnd),crash when close](https://discourse.vtk.org/t/only-depending-on-vtk-use-vtkmfcwindow-and-setparent-hwnd-hwnd-crash-when-close/16261)

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**Author:** [@sophia](https://discourse.vtk.org/u/sophia)\
**Replies:** 0\
**Last updated:** [January 30, 2026, 12:22pm UTC](https://discourse.vtk.org/t/only-depending-on-vtk-use-vtkmfcwindow-and-setparent-hwnd-hwnd-crash-when-close/16261 "2026-01-30T12:22:19Z")

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the stack is below: image1040×819 63.3 KB

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## [VTK 9.5.2 causes segfault for pcl::io::loadPCDFile()](https://discourse.vtk.org/t/vtk-9-5-2-causes-segfault-for-pcl-loadpcdfile/16214)

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**Author:** [@mishio](https://discourse.vtk.org/u/mishio)\
**Replies:** 2\
**Last updated:** [January 30, 2026, 10:53am UTC](https://discourse.vtk.org/t/vtk-9-5-2-causes-segfault-for-pcl-loadpcdfile/16214 "2026-01-30T10:53:10Z")

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A newer version of VTK may be causing segmentation fault on some occasions. Please see pcl::io::loadPCDFile() causes segmentation fault on ubuntu:26.04 · Issue #6388 · PointCloudLibrary/pcl · GitHub .

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## [Polyhedron face connectivity improvements](https://discourse.vtk.org/t/polyhedron-face-connectivity-improvements/16250)

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**Author:** [@Louis\_Gombert](https://discourse.vtk.org/u/Louis_Gombert)\
**Replies:** 5\
**Last updated:** [January 29, 2026, 3:43pm UTC](https://discourse.vtk.org/t/polyhedron-face-connectivity-improvements/16250 "2026-01-29T15:43:44Z")

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Following discussions in the VTKHDF polyhedrons thread, we would like to discuss a potential improvement to the vtkUnstructuredGrid data model that allows reusing the same faces using different orientations in different …

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## [only depending on vtk, no code to call vtk，crash when close](https://discourse.vtk.org/t/only-depending-on-vtk-no-code-to-call-vtk-crash-when-close/16064)

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**Author:** [@sophia](https://discourse.vtk.org/u/sophia)\
**Replies:** 5\
**Last updated:** [January 29, 2026, 7:02am UTC](https://discourse.vtk.org/t/only-depending-on-vtk-no-code-to-call-vtk-crash-when-close/16064 "2026-01-29T07:02:49Z")

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A mfc application use one dll, the dll depend vtk。Free library when close the app, crash in the vtk code “ delete key;“ void vtkCommonInformationKeyManager::ClassFinalize() { … delete key; … } how to reslove the…

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## [\`vtkCommunicator.MarshalDataObject\` mutates locale unexpectedly](https://discourse.vtk.org/t/vtkcommunicator-marshaldataobject-mutates-locale-unexpectedly/16260)

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**Author:** [@user27182](https://discourse.vtk.org/u/user27182)\
**Replies:** 8\
**Last updated:** [January 28, 2026, 6:26pm UTC](https://discourse.vtk.org/t/vtkcommunicator-marshaldataobject-mutates-locale-unexpectedly/16260 "2026-01-28T18:26:18Z")

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This seems like a bug, since I would expect locale not to be mutated when calling vtk code like this: import locale import vtk l = locale.getlocale() e = locale.getencoding() print(f"Locale before: {l}, Encoding: {e}")…

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## [Possible VTKHDF bug](https://discourse.vtk.org/t/possible-vtkhdf-bug/16255)

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**Author:** [@nncarlson](https://discourse.vtk.org/u/nncarlson)\
**Replies:** 6\
**Last updated:** [January 27, 2026, 3:11pm UTC](https://discourse.vtk.org/t/possible-vtkhdf-bug/16255 "2026-01-27T15:11:27Z")

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I’ve developed a VTKHDF writer for our code that is working for small development test cases, but which is causing errors in paraview for large application-like cases. I’m generating a MultiBlockDataSet file with 4 block…

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## [Possible VTK 9.6.0rc2 regression with ghost cell rendering](https://discourse.vtk.org/t/possible-vtk-9-6-0rc2-regression-with-ghost-cell-rendering/16251)

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**Author:** [@user27182](https://discourse.vtk.org/u/user27182)\
**Replies:** 16\
**Last updated:** [January 26, 2026, 8:26pm UTC](https://discourse.vtk.org/t/possible-vtk-9-6-0rc2-regression-with-ghost-cell-rendering/16251 "2026-01-26T20:26:22Z")

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ugrid.vtu (4.4 KB) I have attached an UnstructuredGrid mesh file with a 'vtkGhostType' cell array. The top “row” of cells in the dataset are masked. Using the code below with vtk==9.5.20250802.dev0, we get : But wi…

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## [Fresh gitlab commands for developers](https://discourse.vtk.org/t/fresh-gitlab-commands-for-developers/16240)

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**Author:** [@dgobbi](https://discourse.vtk.org/u/dgobbi)\
**Replies:** 0\
**Last updated:** [January 17, 2026, 3:23pm UTC](https://discourse.vtk.org/t/fresh-gitlab-commands-for-developers/16240 "2026-01-17T15:23:35Z")

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This applies to the VTK master branch and the upcoming 9.6.0 release. All VTK developers are familiar with git gitlab-push, but VTK also provides some other gitlab CLI commands (some only recently added) which can impro…

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## [VTK/Paraview Gitlab "Merge requests" page error in Firefox](https://discourse.vtk.org/t/vtk-paraview-gitlab-merge-requests-page-error-in-firefox/16236)

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**Author:** [@hakostra](https://discourse.vtk.org/u/hakostra)\
**Replies:** 3\
**Last updated:** [January 16, 2026, 8:16am UTC](https://discourse.vtk.org/t/vtk-paraview-gitlab-merge-requests-page-error-in-firefox/16236 "2026-01-16T08:16:06Z")

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Lately, the “Merge requests” page in both VTK and Paraview Gitlab has been showing just an error “An error occurred while loading merge requests” in Firefox on Linux (have not tried Windows). With Chromium it works just …

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## [Adding some ParaView colors to vtkNamedColors](https://discourse.vtk.org/t/adding-some-paraview-colors-to-vtknamedcolors/16220)

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**Author:** [@amaclean](https://discourse.vtk.org/u/amaclean)\
**Replies:** 7\
**Last updated:** [January 14, 2026, 9:15pm UTC](https://discourse.vtk.org/t/adding-some-paraview-colors-to-vtknamedcolors/16220 "2026-01-14T21:15:57Z")

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ParaView has two nicely balanced and really useful background colors that now appear quite a lot in the VTK Examples, namely ParaViewBlueGrayBkg and ParaViewWarmGrayBkg. What do people think about adding these colors to…

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## [Support PLY with texture coordinates parameters named (s, t)](https://discourse.vtk.org/t/support-ply-with-texture-coordinates-parameters-named-s-t/16197)

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**Author:** [@afavray.modjaw](https://discourse.vtk.org/u/afavray.modjaw)\
**Replies:** 7\
**Last updated:** [January 14, 2026, 11:14am UTC](https://discourse.vtk.org/t/support-ply-with-texture-coordinates-parameters-named-s-t/16197 "2026-01-14T11:14:33Z")

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Hello, I am using vtkPLYReader to import various PLY meshes in my project (python VTK 9.5.2). I have a problem with some PLY file formats that use external texture : the vtkPLYReader fails to parse texture coordinates …

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## [Wrong orientation of principal vector generated by vtkTensorPrincipalInvariants](https://discourse.vtk.org/t/wrong-orientation-of-principal-vector-generated-by-vtktensorprincipalinvariants/16218)

<div class="topic-metadata">

**Author:** [@npoletz](https://discourse.vtk.org/u/npoletz)\
**Replies:** 2\
**Last updated:** [January 12, 2026, 9:26am UTC](https://discourse.vtk.org/t/wrong-orientation-of-principal-vector-generated-by-vtktensorprincipalinvariants/16218 "2026-01-12T09:26:36Z")

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Hello, I believe there is an error in the principal vector orientations produced by vtkTensorPrincipalInvariants. In the image below, the diagonal tensor \[1, 2, 3\] (left) and its version rotated counterclockwise by π/6…

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