# Web

**URL:** https://discourse.vtk.org/c/web/9.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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## [Disable rotaion in vtkResliceImageViewer's cursorwidget.](https://discourse.vtk.org/t/disable-rotaion-in-vtkresliceimageviewers-cursorwidget/16212)

<div class="topic-metadata">

**Author:** [@KSJ](https://discourse.vtk.org/u/KSJ)\
**Replies:** 0\
**Last updated:** [January 6, 2026, 11:29am UTC](https://discourse.vtk.org/t/disable-rotaion-in-vtkresliceimageviewers-cursorwidget/16212 "2026-01-06T11:29:01Z")

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I am using vtkResliceImageViewer to display DICOM images. It has a built-in 2D crosshair that intersects the image. By default, interacting with the crosshair allows both translation and rotation, and rotating the crossh…

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## [Doesn't unpkg.com/vtk.js include the vtkSeedWidget?](https://discourse.vtk.org/t/doesnt-unpkg-com-vtk-js-include-the-vtkseedwidget/16205)

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**Author:** [@fdlyj](https://discourse.vtk.org/u/fdlyj)\
**Replies:** 0\
**Last updated:** [January 2, 2026, 4:24am UTC](https://discourse.vtk.org/t/doesnt-unpkg-com-vtk-js-include-the-vtkseedwidget/16205 "2026-01-02T04:24:10Z")

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Doesn’t unpkg.com/vtk.js include the vtkSeedWidget?

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## [Hide cells in vtk.js](https://discourse.vtk.org/t/hide-cells-in-vtk-js/15735)

<div class="topic-metadata">

**Author:** [@davsch](https://discourse.vtk.org/u/davsch)\
**Replies:** 11\
**Last updated:** [December 31, 2025, 6:20am UTC](https://discourse.vtk.org/t/hide-cells-in-vtk-js/15735 "2025-12-31T06:20:20Z")

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Is there a way to hide specific cells in vtk.js? Something like scalar celldata with a specific value don’t get rendered. Already tried assigning alpha value to a LUT or hiding specific points with ThresholdPoints and …

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## [Using wslink on AWS gateway](https://discourse.vtk.org/t/using-wslink-on-aws-gateway/16196)

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**Author:** [@BotellaA](https://discourse.vtk.org/u/BotellaA)\
**Replies:** 3\
**Last updated:** [December 21, 2025, 8:28am UTC](https://discourse.vtk.org/t/using-wslink-on-aws-gateway/16196 "2025-12-21T08:28:51Z")

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I have a vtk web app running on aws fargate through a load balancer. I am reading some articles about websocket API gateway. Did someone have experience with this service? Looks like a good candidate to have a serverless…

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## [Reslice Cursor Widget Mapper About](https://discourse.vtk.org/t/reslice-cursor-widget-mapper-about/16181)

<div class="topic-metadata">

**Author:** [@selimcanozgur](https://discourse.vtk.org/u/selimcanozgur)\
**Replies:** 1\
**Last updated:** [December 18, 2025, 5:24pm UTC](https://discourse.vtk.org/t/reslice-cursor-widget-mapper-about/16181 "2025-12-18T17:24:31Z")

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I’m using VTK.JS in my project, and when I try to add the reslice cursor widget feature and display it in a rotated (oblique) section, it seems to require resliceImageMapper. However, my drawings are created using Ima…

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## [How to change the position of scalar bar on VTK.js](https://discourse.vtk.org/t/how-to-change-the-position-of-scalar-bar-on-vtk-js/13082)

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**Author:** [@Ossama\_Elbelamachi](https://discourse.vtk.org/u/Ossama_Elbelamachi)\
**Replies:** 2\
**Last updated:** [November 5, 2025, 12:41pm UTC](https://discourse.vtk.org/t/how-to-change-the-position-of-scalar-bar-on-vtk-js/13082 "2025-11-05T12:41:52Z")

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Hello Everyone I hope you are doing well How can change the position of the scalar bar to be fixed to the bottom of the canvas I tried to use the vtkScalarBarActor and set the bar position using the setBarPosition meth…

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## [Cannot read properties of undefined (reading '0') when switching to Oblique View](https://discourse.vtk.org/t/cannot-read-properties-of-undefined-reading-0-when-switching-to-oblique-view/16115)

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**Author:** [@Pranathi\_Induri](https://discourse.vtk.org/u/Pranathi_Induri)\
**Replies:** 1\
**Last updated:** [November 3, 2025, 1:11pm UTC](https://discourse.vtk.org/t/cannot-read-properties-of-undefined-reading-0-when-switching-to-oblique-view/16115 "2025-11-03T13:11:44Z")

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When I load a DICOM CT dataset and try to switch to the “Oblique View” layout, VolView throws a TypeError: Cannot read properties of undefined (reading ‘0’) error. The standard views (Quad View, Axial Primary, etc.) work…

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## [vtkPiecewiseGaussianWidget for window/level or CTF editing in 2D](https://discourse.vtk.org/t/vtkpiecewisegaussianwidget-for-window-level-or-ctf-editing-in-2d/16116)

<div class="topic-metadata">

**Author:** [@vojtech](https://discourse.vtk.org/u/vojtech)\
**Replies:** 0\
**Last updated:** [October 29, 2025, 8:11pm UTC](https://discourse.vtk.org/t/vtkpiecewisegaussianwidget-for-window-level-or-ctf-editing-in-2d/16116 "2025-10-29T20:11:01Z")

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I’m developing a 2D image viewer in VTK.js (using vtkImageSlice + vtkImageMapper) and I’d like to provide an interactive window/level (intensity range) editor. With given LUT/CTF I’d like to achieve: Let the user adj…

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## [How to build vtk-wasm64](https://discourse.vtk.org/t/how-to-build-vtk-wasm64/13574)

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**Author:** [@pqng](https://discourse.vtk.org/u/pqng)\
**Replies:** 5\
**Last updated:** [October 29, 2025, 4:00pm UTC](https://discourse.vtk.org/t/how-to-build-vtk-wasm64/13574 "2025-10-29T16:00:37Z")

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Hi, I am experimenting with \>4GB limitation using vtk-wasm. However, I am getting error wasm32 object file can’t be linked in wasm64 mode. How do I compile vtk-wasm in wasm64 to test this? Thanks,

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## [Why importing vtkmodules.vtkRenderingVolumeOpenGL2 is mandatory?](https://discourse.vtk.org/t/why-importing-vtkmodules-vtkrenderingvolumeopengl2-is-mandatory/16107)

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**Author:** [@BotellaA](https://discourse.vtk.org/u/BotellaA)\
**Replies:** 2\
**Last updated:** [October 22, 2025, 7:28pm UTC](https://discourse.vtk.org/t/why-importing-vtkmodules-vtkrenderingvolumeopengl2-is-mandatory/16107 "2025-10-22T19:28:00Z")

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I have a simple VTKWeb app with a pytest integration. It works when I import every vtk object using import vtk. I am trying to control the import better by importing directly from vtkmodules. Now the test is failing wit…

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## [Color Images Not Rendering After Upgrade to vtk.js 34.0.0](https://discourse.vtk.org/t/color-images-not-rendering-after-upgrade-to-vtk-js-34-0-0/16104)

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**Author:** [@Alireza](https://discourse.vtk.org/u/Alireza)\
**Replies:** 4\
**Last updated:** [October 21, 2025, 6:43pm UTC](https://discourse.vtk.org/t/color-images-not-rendering-after-upgrade-to-vtk-js-34-0-0/16104 "2025-10-21T18:43:30Z")

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After upgrading from vtk.js 33.x to 34.0.0, color (RGB) images are no longer rendering in our stack viewport (source code) , while grayscale images continue to work fine. I’ve reviewed the diff between versions 33 and 34…

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## [The web version of STLReader getNumberOfPoints results are different from the python version](https://discourse.vtk.org/t/the-web-version-of-stlreader-getnumberofpoints-results-are-different-from-the-python-version/11415)

<div class="topic-metadata">

**Author:** [@qq769747518](https://discourse.vtk.org/u/qq769747518)\
**Replies:** 3\
**Last updated:** [October 21, 2025, 2:23pm UTC](https://discourse.vtk.org/t/the-web-version-of-stlreader-getnumberofpoints-results-are-different-from-the-python-version/11415 "2025-10-21T14:23:01Z")

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The same stl file. in the web, I got the following result const STLReader = vtkSTLReader.newInstance(); await STLReader.setUrl("/stl/a\_Cup.stl"); const pointNum = STLReader.getOutputData().getNumberOfPoints(); …

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## [vtk.js: Image renders black, but Cube renders fine – vtkImageData + vtkImageSlice issue](https://discourse.vtk.org/t/vtk-js-image-renders-black-but-cube-renders-fine-vtkimagedata-vtkimageslice-issue/16097)

<div class="topic-metadata">

**Author:** [@vojtech](https://discourse.vtk.org/u/vojtech)\
**Replies:** 1\
**Last updated:** [October 20, 2025, 3:19pm UTC](https://discourse.vtk.org/t/vtk-js-image-renders-black-but-cube-renders-fine-vtkimagedata-vtkimageslice-issue/16097 "2025-10-20T15:19:39Z")

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I’m using vtk.js inside a React component to render a 2D image slice using vtkImageData and vtkImageSlice. While 3D geometry primitives like vtkCubeSource render correctly (e.g., a cube appears as expected), my 2D image …

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## [trame vtk wasm & space mouse](https://discourse.vtk.org/t/trame-vtk-wasm-space-mouse/16063)

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**Author:** [@jtristanod3d](https://discourse.vtk.org/u/jtristanod3d)\
**Replies:** 4\
**Last updated:** [October 10, 2025, 1:34pm UTC](https://discourse.vtk.org/t/trame-vtk-wasm-space-mouse/16063 "2025-10-10T13:34:33Z")

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How do I enable vtk wasm, trame with space mouse support in the browser?

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## [vtk wasm script error not a VtkRenderWindow](https://discourse.vtk.org/t/vtk-wasm-script-error-not-a-vtkrenderwindow/16076)

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**Author:** [@jtristanod3d](https://discourse.vtk.org/u/jtristanod3d)\
**Replies:** 3\
**Last updated:** [October 8, 2025, 12:27pm UTC](https://discourse.vtk.org/t/vtk-wasm-script-error-not-a-vtkrenderwindow/16076 "2025-10-08T12:27:30Z")

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Wether using samples or my own apps, I get this console error. Is this something I need to be worried about? 2025-10-01 10:35:33.062 ( 0.039s) \[ 7F5534\] vtkSession.cxx:290 ERR| Object null at id=1…

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## [pvd , vtu , vti files with vtk wasm](https://discourse.vtk.org/t/pvd-vtu-vti-files-with-vtk-wasm/16060)

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**Author:** [@jtristanod3d](https://discourse.vtk.org/u/jtristanod3d)\
**Replies:** 10\
**Last updated:** [October 8, 2025, 10:08am UTC](https://discourse.vtk.org/t/pvd-vtu-vti-files-with-vtk-wasm/16060 "2025-10-08T10:08:44Z")

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Hi, I am a paraview and pyvista user. I’ve stayed away from trame and vtk.js due to server side rendering and slow js rendering. Now that you have vtk wasm I want a simple page to just load a pvd file from disk and plo…

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## [GL\_DEPTH\_COMPONENT32 in opengl es](https://discourse.vtk.org/t/gl-depth-component32-in-opengl-es/16082)

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**Author:** [@Francois\_Merle](https://discourse.vtk.org/u/Francois_Merle)\
**Replies:** 2\
**Last updated:** [October 7, 2025, 2:58pm UTC](https://discourse.vtk.org/t/gl-depth-component32-in-opengl-es/16082 "2025-10-07T14:58:48Z")

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Hi, I’m making an application where I show a vtkImageData in 3D in a QQuickVTKWindow using a vtkSmartVolumeMapper. As vtk is rendering it, there is a warning displayed : GL\_INVALID\_OPERATION: glBlitFramebuffer: Depth/s…

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## [How to access resliced image data from vtkImageResliceMapper in VTK.js](https://discourse.vtk.org/t/how-to-access-resliced-image-data-from-vtkimagereslicemapper-in-vtk-js/16078)

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**Author:** [@shuj](https://discourse.vtk.org/u/shuj)\
**Replies:** 3\
**Last updated:** [October 6, 2025, 7:15pm UTC](https://discourse.vtk.org/t/how-to-access-resliced-image-data-from-vtkimagereslicemapper-in-vtk-js/16078 "2025-10-06T19:15:59Z")

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Hi, I’m trying to retrieve pixel data from a slice rendered using vtkImageResliceMapper in VTK.js. Specifically, I want to access the resliced output as a pixel array to count the occurrence of each pixel colour. Initi…

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## [How to draw UIs on top of the image](https://discourse.vtk.org/t/how-to-draw-uis-on-top-of-the-image/15133)

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**Author:** [@shunia](https://discourse.vtk.org/u/shunia)\
**Replies:** 7\
**Last updated:** [October 2, 2025, 10:43pm UTC](https://discourse.vtk.org/t/how-to-draw-uis-on-top-of-the-image/15133 "2025-10-02T22:43:51Z")

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I want to build flexable UIs just like in webgl games that the UIs looks like they are related to the screen rather than the actual 3D objects in the 3D space, and the UIs looks and feels like 2D, as they are just texts,…

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## [Is VTK.js performance GPU/browser dependent?](https://discourse.vtk.org/t/is-vtk-js-performance-gpu-browser-dependent/16077)

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**Author:** [@Pranathi\_Induri](https://discourse.vtk.org/u/Pranathi_Induri)\
**Replies:** 1\
**Last updated:** [October 2, 2025, 4:10pm UTC](https://discourse.vtk.org/t/is-vtk-js-performance-gpu-browser-dependent/16077 "2025-10-02T16:10:41Z")

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Is VTK.js performance dependent on the GPU and browser ? With the same app and data, it runs smoothly on a laptop with an NVIDIA GPU but lags a on an Intel integrated GPU (in Chrome). Are there simple settings or best pr…

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## [TransformControlsWidget](https://discourse.vtk.org/t/transformcontrolswidget/16066)

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**Author:** [@lmj01](https://discourse.vtk.org/u/lmj01)\
**Replies:** 2\
**Last updated:** [September 29, 2025, 8:06am UTC](https://discourse.vtk.org/t/transformcontrolswidget/16066 "2025-09-29T08:06:16Z")

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Widget TransformControlsWidget how work ? it default is the coordinate origin, how can attach one actor to it ? or its design purpos is what ? I think i dont’s understand it, but on the code repo at github, it would li…

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## [Polydata outline](https://discourse.vtk.org/t/polydata-outline/14708)

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**Author:** [@antonskrebkov](https://discourse.vtk.org/u/antonskrebkov)\
**Replies:** 1\
**Last updated:** [September 28, 2025, 10:16am UTC](https://discourse.vtk.org/t/polydata-outline/14708 "2025-09-28T10:16:22Z")

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Hello everyone! Is there a function in vtk.js that would allow making an outline for polydata, but not just a cube in which the figure would be located (as in outlineFilter), but something like a wireframe representatio…

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## [I need to visualize .vtu file in react using vtk.js,](https://discourse.vtk.org/t/i-need-to-visualize-vtu-file-in-react-using-vtk-js/15002)

<div class="topic-metadata">

**Author:** [@HARIPRASATH\_Y\_S](https://discourse.vtk.org/u/HARIPRASATH_Y_S)\
**Replies:** 1\
**Last updated:** [September 28, 2025, 10:08am UTC](https://discourse.vtk.org/t/i-need-to-visualize-vtu-file-in-react-using-vtk-js/15002 "2025-09-28T10:08:37Z")

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does vtkXmlReader supports that feature, i have tried but it showed error, But for web vtkxmlunstructureGrid is not available, without using vtk-wasm is there any other way to do it… If possible can you please suggest th…

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## [vtkLineWidget Handle Visible](https://discourse.vtk.org/t/vtklinewidget-handle-visible/15689)

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**Author:** [@Taz145](https://discourse.vtk.org/u/Taz145)\
**Replies:** 1\
**Last updated:** [September 28, 2025, 10:05am UTC](https://discourse.vtk.org/t/vtklinewidget-handle-visible/15689 "2025-09-28T10:05:13Z")

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In the source for the vtkLineWidget there are references to being able to make the handles non-visible but still intractable by the user. I am attempting to draw SVG elements where the handles are, the same as glance and…

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## [Orientation with vtkImageResliceMapper and vtkVolumeMapper](https://discourse.vtk.org/t/orientation-with-vtkimagereslicemapper-and-vtkvolumemapper/15772)

<div class="topic-metadata">

**Author:** [@twilson](https://discourse.vtk.org/u/twilson)\
**Replies:** 1\
**Last updated:** [September 28, 2025, 9:55am UTC](https://discourse.vtk.org/t/orientation-with-vtkimagereslicemapper-and-vtkvolumemapper/15772 "2025-09-28T09:55:55Z")

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I am new to vtk.js and experiencing some unexpected orientation related issues. I have tried my code with both my custom data loader as well as the itk-wasm loader and got the same results in both cases. I am loading a s…

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## [Using ImageMarchingCubes exceeds the array length limit.](https://discourse.vtk.org/t/using-imagemarchingcubes-exceeds-the-array-length-limit/15808)

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**Author:** [@Heisenberg](https://discourse.vtk.org/u/Heisenberg)\
**Replies:** 1\
**Last updated:** [September 28, 2025, 9:49am UTC](https://discourse.vtk.org/t/using-imagemarchingcubes-exceeds-the-array-length-limit/15808 "2025-09-28T09:49:50Z")

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Hello everyone, I have just started learning vtk.js. Due to the large size of my data (210x676x676), when I was using ImageMarchingCubes, I exceeded the array length. Is there any solution to this problem?

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## [About VTK JS Reslice Cursor Widget](https://discourse.vtk.org/t/about-vtk-js-reslice-cursor-widget/15857)

<div class="topic-metadata">

**Author:** [@selimcanozgur](https://discourse.vtk.org/u/selimcanozgur)\
**Replies:** 1\
**Last updated:** [September 28, 2025, 9:46am UTC](https://discourse.vtk.org/t/about-vtk-js-reslice-cursor-widget/15857 "2025-09-28T09:46:53Z")

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I’m using vtk.js for my project and have integrated the Reslice Cursor Widget feature. We have both NIfTI and Draco data, and all of them are rendered correctly on the screen without any issues. Each NIfTI file has its o…

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## [Regarding the rendering error of the VTK DataFile Version 5.1 model PolyDataReader](https://discourse.vtk.org/t/regarding-the-rendering-error-of-the-vtk-datafile-version-5-1-model-polydatareader/15961)

<div class="topic-metadata">

**Author:** [@iridescence97](https://discourse.vtk.org/u/iridescence97)\
**Replies:** 1\
**Last updated:** [September 28, 2025, 9:41am UTC](https://discourse.vtk.org/t/regarding-the-rendering-error-of-the-vtk-datafile-version-5-1-model-polydatareader/15961 "2025-09-28T09:41:45Z")

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async function readPolyData(file: File) { const toBlob = new Blob(\[file\]) const fileBlob = URL.createObjectURL(toBlob) const reader = vtkPolyDataReader.newInstance() await reader.setUrl(fileBlob) awa…

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## [using ImageReslice in js can not get the slice data like ImageSlicing.cxx](https://discourse.vtk.org/t/using-imagereslice-in-js-can-not-get-the-slice-data-like-imageslicing-cxx/16053)

<div class="topic-metadata">

**Author:** [@1009058470](https://discourse.vtk.org/u/1009058470)\
**Replies:** 2\
**Last updated:** [September 24, 2025, 10:34pm UTC](https://discourse.vtk.org/t/using-imagereslice-in-js-can-not-get-the-slice-data-like-imageslicing-cxx/16053 "2025-09-24T22:34:54Z")

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\<!DOCTYPE html\> \<html lang="en"\> \<head\> \<meta charset="UTF-8"\> \<meta name="viewport" content="width=device-width, initial-scale=1.0"\> \<title\>VTK.js (使用ImageReslice)\</title\> \<script src="https://unpkg.com…

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## [VTKJS Image Filters (Sharpening, Finegrain, etc)](https://discourse.vtk.org/t/vtkjs-image-filters-sharpening-finegrain-etc/16045)

<div class="topic-metadata">

**Author:** [@IbrahimCSAE](https://discourse.vtk.org/u/IbrahimCSAE)\
**Replies:** 2\
**Last updated:** [September 17, 2025, 4:09am UTC](https://discourse.vtk.org/t/vtkjs-image-filters-sharpening-finegrain-etc/16045 "2025-09-17T04:09:41Z")

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Hi, I was wondering if there’s an efficent way to implement image filters using VTKJS. Specially for medical imaging. Filters like fine grain, sharpening, CLAHE, etc. I saw this example in python: https://examples.vtk…

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