# Latest

**URL:** https://discourse.vtk.org/latest.md?page=132

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

**Page:** 133

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## [Transform from vtkCONVERGEReader to PolyData.](https://discourse.vtk.org/t/transform-from-vtkconvergereader-to-polydata/8507)

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**Author:** [@Jamargi](https://discourse.vtk.org/u/Jamargi)\
**Replies:** 0\
**Last updated:** [May 16, 2022, 3:38pm UTC](https://discourse.vtk.org/t/transform-from-vtkconvergereader-to-polydata/8507 "2022-05-16T15:38:30Z")

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Good morning, I am trying to use the reader class vtkCONVERGECFDReader to some object that I can easily work with. I have managed to do so with only one file in the folder, but if a time series is located on my working …

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## [VTK And Flutter - How to?](https://discourse.vtk.org/t/vtk-and-flutter-how-to/6065)

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**Author:** [@Uriel\_Dardik](https://discourse.vtk.org/u/Uriel_Dardik)\
**Replies:** 1\
**Last updated:** [May 16, 2022, 6:42am UTC](https://discourse.vtk.org/t/vtk-and-flutter-how-to/6065 "2022-05-16T06:42:49Z")

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Does anyone have any experience working with VTK in Flutter? Is this mission can be done? Where do I start? Any type of answer that shed some light on this topic will be very helpful, Thanks!

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## [VTK-9.1.0 with FFMPEG-5.0 ?](https://discourse.vtk.org/t/vtk-9-1-0-with-ffmpeg-5-0/8486)

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**Author:** [@jiapei100](https://discourse.vtk.org/u/jiapei100)\
**Replies:** 3\
**Last updated:** [May 15, 2022, 1:42pm UTC](https://discourse.vtk.org/t/vtk-9-1-0-with-ffmpeg-5-0/8486 "2022-05-15T13:42:42Z")

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Hi, all: I’m trying to build \*\*VTK-9.1.0 \*\* on Ubuntu 22.04, with gcc-11.2. with VTK\_BUILD\_ALL\_MODULES ON. And I’ve already installed FFMPEG-5.0 on my system. It looks so far VTK-9.1.0 is NOT compatible wi…

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## [index array or boolean array from vtkSelection](https://discourse.vtk.org/t/index-array-or-boolean-array-from-vtkselection/8495)

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**Author:** [@Kiordestruk\_k](https://discourse.vtk.org/u/Kiordestruk_k)\
**Replies:** 0\
**Last updated:** [May 15, 2022, 1:29pm UTC](https://discourse.vtk.org/t/index-array-or-boolean-array-from-vtkselection/8495 "2022-05-15T13:29:52Z")

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Hello, I would like to get a numpy array of integer indices or a numpy boolean mask from a vtkSelection object in Python : def get\_visible\_vertices(plotter, pv\_mesh): # perfrom the automatic picking selector = v…

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## [VTK-9.1.0 vtkm failed to build](https://discourse.vtk.org/t/vtk-9-1-0-vtkm-failed-to-build/8490)

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**Author:** [@jiapei100](https://discourse.vtk.org/u/jiapei100)\
**Replies:** 1\
**Last updated:** [May 15, 2022, 12:24pm UTC](https://discourse.vtk.org/t/vtk-9-1-0-vtkm-failed-to-build/8490 "2022-05-15T12:24:05Z")

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Hi, all: I’m trying to buld VTK-9.1.0 release, but failed. My ENV: ➜ ~ uname -r 5.15.0-30-generic ➜ ~ lsb\_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 22.04 LTS Release: 22.04…

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## [Extract skull from Dicom](https://discourse.vtk.org/t/extract-skull-from-dicom/8481)

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**Author:** [@perphy](https://discourse.vtk.org/u/perphy)\
**Replies:** 3\
**Last updated:** [May 13, 2022, 12:59pm UTC](https://discourse.vtk.org/t/extract-skull-from-dicom/8481 "2022-05-13T12:59:57Z")

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Hi: I am trying to extract the skull model from series of Dicom files. I used vtkDICOMImageReader and vtkMarchingCubes. Here is the result I wish only get the skull model like the example Headbone https://kitware…

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## [how can i draw a straight horizontal line using line widget?](https://discourse.vtk.org/t/how-can-i-draw-a-straight-horizontal-line-using-line-widget/8487)

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**Author:** [@Sneha-pk](https://discourse.vtk.org/u/Sneha-pk)\
**Replies:** 0\
**Last updated:** [May 13, 2022, 8:11am UTC](https://discourse.vtk.org/t/how-can-i-draw-a-straight-horizontal-line-using-line-widget/8487 "2022-05-13T08:11:35Z")

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I am trying to draw a line using line widget and want to set the line straight. Is the method \[SetAlignToXAxis\] available in vtk.js?? Also, are all of the methods mentioned in vtkLineWidget class(https://vtk.org/doc/nig…

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## [How to clean duplicate points after cut-through cells using vtkTableBasedClipDataSet?](https://discourse.vtk.org/t/how-to-clean-duplicate-points-after-cut-through-cells-using-vtktablebasedclipdataset/8468)

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**Author:** [@xxyyy159](https://discourse.vtk.org/u/xxyyy159)\
**Replies:** 1\
**Last updated:** [May 13, 2022, 3:55am UTC](https://discourse.vtk.org/t/how-to-clean-duplicate-points-after-cut-through-cells-using-vtktablebasedclipdataset/8468 "2022-05-13T03:55:34Z")

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HI, I 'm using vtkTableBasedClipDataSet to cut a cylinder. It works fairly well. But when cutting along a same plane(implicit function) multiple times, some duplicate points would present in the output. As a result, the…

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## [Best way to get notified of camera changes - specifically zoom](https://discourse.vtk.org/t/best-way-to-get-notified-of-camera-changes-specifically-zoom/8477)

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**Author:** [@bheld](https://discourse.vtk.org/u/bheld)\
**Replies:** 3\
**Last updated:** [May 13, 2022, 12:02am UTC](https://discourse.vtk.org/t/best-way-to-get-notified-of-camera-changes-specifically-zoom/8477 "2022-05-13T00:02:25Z")

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We have various ways we allow users to zoom in our application such as buttons for fit by window, dynamic zoom that works by depressing mouse button and moving the mouse, zoom by window, etc. I’m looking for the best wa…

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## [multiple render views share a widgetState](https://discourse.vtk.org/t/multiple-render-views-share-a-widgetstate/8467)

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**Author:** [@654545342](https://discourse.vtk.org/u/654545342)\
**Replies:** 3\
**Last updated:** [May 12, 2022, 10:27am UTC](https://discourse.vtk.org/t/multiple-render-views-share-a-widgetstate/8467 "2022-05-12T10:27:13Z")

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I want to share a widgetState across multiple render views, but I don’t know how to add or bind widgetState to widgets after factory generation. Is there anyone who can help me? I really hope to receive your reply

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## [ShallowCopy cost more time than building itself](https://discourse.vtk.org/t/shallowcopy-cost-more-time-than-building-itself/8472)

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**Author:** [@Ren](https://discourse.vtk.org/u/Ren)\
**Replies:** 3\
**Last updated:** [May 12, 2022, 8:43am UTC](https://discourse.vtk.org/t/shallowcopy-cost-more-time-than-building-itself/8472 "2022-05-12T08:43:36Z")

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Hello, everyone, I would like to create a actor, the poly data shallow copies from another actor, For some models, why ShallowCopy takes too long time even than building data itself? For some models, it is indeed fast. …

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## [Outline/silhouette a subset of points](https://discourse.vtk.org/t/outline-silhouette-a-subset-of-points/8470)

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**Author:** [@CharInt0](https://discourse.vtk.org/u/CharInt0)\
**Replies:** 1\
**Last updated:** [May 12, 2022, 6:42am UTC](https://discourse.vtk.org/t/outline-silhouette-a-subset-of-points/8470 "2022-05-12T06:42:54Z")

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Hello, I am trying to add an outline (or better a silhouette) to a subset of points visualized as a Glyph3D. I already managed to change the color to the subset points. In my code, I use vtkExtractGeometry and vtkVertex…

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## [(Python) Is there a way to Parallel Render with VTK?](https://discourse.vtk.org/t/python-is-there-a-way-to-parallel-render-with-vtk/8460)

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**Author:** [@joaomlap](https://discourse.vtk.org/u/joaomlap)\
**Replies:** 1\
**Last updated:** [May 12, 2022, 3:29am UTC](https://discourse.vtk.org/t/python-is-there-a-way-to-parallel-render-with-vtk/8460 "2022-05-12T03:29:25Z")

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I am trying to follow the example showed here: https://gitlab.kitware.com/vtk/vtk/-/blob/v9.1.0/Examples/ParallelProcessing/Generic/Cxx/TaskParallelism.cxx to allow me to parallel render a vtkMultiBlockDataset, the data…

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## [Bug with vtk Boolean Operation PolyData Filter and implicit functions?](https://discourse.vtk.org/t/bug-with-vtk-boolean-operation-polydata-filter-and-implicit-functions/8479)

<div class="topic-metadata">

**Author:** [@BlueKnight7](https://discourse.vtk.org/u/BlueKnight7)\
**Replies:** 0\
**Last updated:** [May 12, 2022, 12:57am UTC](https://discourse.vtk.org/t/bug-with-vtk-boolean-operation-polydata-filter-and-implicit-functions/8479 "2022-05-12T00:57:28Z")

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This could be a bug or it could be something that I don’t have right with the implementation. The following code correctly renders the UNION of two spheres using the vtkBooleanOperationPolyDataFilter class. BooleanOpe…

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## [How to mark different marked areas with different colors when marking with the paintWidget?](https://discourse.vtk.org/t/how-to-mark-different-marked-areas-with-different-colors-when-marking-with-the-paintwidget/8396)

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**Author:** [@zuolx](https://discourse.vtk.org/u/zuolx)\
**Replies:** 4\
**Last updated:** [May 11, 2022, 3:51pm UTC](https://discourse.vtk.org/t/how-to-mark-different-marked-areas-with-different-colors-when-marking-with-the-paintwidget/8396 "2022-05-11T15:51:33Z")

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For PaintWidget(vtk.js) In the examples of vtk.js website, I want to dynamic change the RGBpoint’s color, i have try many ways ,but not find a correct method. can you help me?

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## [Change vtkImageCroppingWidget handle radius](https://discourse.vtk.org/t/change-vtkimagecroppingwidget-handle-radius/8454)

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**Author:** [@seattlewayne](https://discourse.vtk.org/u/seattlewayne)\
**Replies:** 1\
**Last updated:** [May 11, 2022, 3:30pm UTC](https://discourse.vtk.org/t/change-vtkimagecroppingwidget-handle-radius/8454 "2022-05-11T15:30:24Z")

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I am attempting to use a vtkImageCroppingWidget, but the handles end up being rendered much to large to be useful. How does one adjust the handle size? Looking at the example and the source it is not obvious how to solve…

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## [Transform/Rotate polyData for OBBTree Intersection (vtk.js)](https://discourse.vtk.org/t/transform-rotate-polydata-for-obbtree-intersection-vtk-js/8476)

<div class="topic-metadata">

**Author:** [@BryonLewis](https://discourse.vtk.org/u/BryonLewis)\
**Replies:** 3\
**Last updated:** [May 11, 2022, 2:49pm UTC](https://discourse.vtk.org/t/transform-rotate-polydata-for-obbtree-intersection-vtk-js/8476 "2022-05-11T14:49:32Z")

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This is probably a simple issue but I can’t seem to figure it out currently. I have some geometry that I want to do some intersection displaying on. I can properly get it to load the data for a vtkXMLPoloyDataReader an…

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## [Adding an "arrays range over time" information key in vtkDataObject](https://discourse.vtk.org/t/adding-an-arrays-range-over-time-information-key-in-vtkdataobject/8398)

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**Author:** [@nicolas.vuaille](https://discourse.vtk.org/u/nicolas.vuaille)\
**Replies:** 5\
**Last updated:** [May 11, 2022, 2:03pm UTC](https://discourse.vtk.org/t/adding-an-arrays-range-over-time-information-key-in-vtkdataobject/8398 "2022-05-11T14:03:32Z")

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Use case We read some temporal data and in the visualization pipeline, we choose an array and we want to setup a lookup table with the union of all the data ranges over time (i.e. from the absolute min over time to absol…

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## [Initial Render() for multiple vtkRenderWindow is slow](https://discourse.vtk.org/t/initial-render-for-multiple-vtkrenderwindow-is-slow/8465)

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**Author:** [@mohamadamoud](https://discourse.vtk.org/u/mohamadamoud)\
**Replies:** 2\
**Last updated:** [May 10, 2022, 6:57pm UTC](https://discourse.vtk.org/t/initial-render-for-multiple-vtkrenderwindow-is-slow/8465 "2022-05-10T18:57:20Z")

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I want to render about 40 vtkRenderWindow objects each with its own image. The issue is my initial render is slow, it takes about 100-200 ms per render window. My pipeline can be seen in the code below. I am using vtk8…

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## [Cell Locators: Support Linear Transformations](https://discourse.vtk.org/t/cell-locators-support-linear-transformations/8449)

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**Author:** [@spyridon97](https://discourse.vtk.org/u/spyridon97)\
**Replies:** 33\
**Last updated:** [May 10, 2022, 6:42pm UTC](https://discourse.vtk.org/t/cell-locators-support-linear-transformations/8449 "2022-05-10T18:42:50Z")

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When operating on datasets that vary over time, the new timesteps are often either the same or a linear transformation of the first timestep. As of now, in the case of linear transformations, when a cell locator is util…

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## [How to show the position of slices？](https://discourse.vtk.org/t/how-to-show-the-position-of-slices/8298)

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**Author:** [@zhangzhi93](https://discourse.vtk.org/u/zhangzhi93)\
**Replies:** 3\
**Last updated:** [May 10, 2022, 2:14pm UTC](https://discourse.vtk.org/t/how-to-show-the-position-of-slices/8298 "2022-05-10T14:14:09Z")

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I want to achieve this effect that can display the position of i,j,k slices in real time. But the example found is written in python, my main language is JavaScript, and by looking at the source code of this python ex…

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## [Gradient Opacity transfer function range](https://discourse.vtk.org/t/gradient-opacity-transfer-function-range/8169)

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**Author:** [@Jiayi\_Xu](https://discourse.vtk.org/u/Jiayi_Xu)\
**Replies:** 3\
**Last updated:** [May 10, 2022, 12:55pm UTC](https://discourse.vtk.org/t/gradient-opacity-transfer-function-range/8169 "2022-05-10T12:55:57Z")

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Hi all, I’m exploring the gradient opacity transfer function in vtkVolumeProperty. According to this old post, the range of opacity function X axis is data dependent. But in the default shader (obtained by dumping shade…

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## [MacOS Font Render is Jaggy (VTK 9.1)](https://discourse.vtk.org/t/macos-font-render-is-jaggy-vtk-9-1/8415)

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**Author:** [@Michael\_Jackson](https://discourse.vtk.org/u/Michael_Jackson)\
**Replies:** 8\
**Last updated:** [May 9, 2022, 3:30pm UTC](https://discourse.vtk.org/t/macos-font-render-is-jaggy-vtk-9-1/8415 "2022-05-09T15:30:46Z")

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I know this has been asked in the past but I just cant seem to find the posts. How does one get the font for things like the CubeAxisActor to look “nice” on macOS? They are all jaggy on my macOS machine but nice looking …

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## [vtkImplicitBoolean Nested Operations Example Needed](https://discourse.vtk.org/t/vtkimplicitboolean-nested-operations-example-needed/8445)

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**Author:** [@BlueKnight7](https://discourse.vtk.org/u/BlueKnight7)\
**Replies:** 0\
**Last updated:** [May 8, 2022, 9:24pm UTC](https://discourse.vtk.org/t/vtkimplicitboolean-nested-operations-example-needed/8445 "2022-05-08T21:24:43Z")

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The https://vtk.org/doc/nightly/html/classvtkImplicitBoolean.html webpage mentions " You can use nested combinations of vtkImplicitFunction’s (and/or vtkImplicitBoolean) to create elaborate implicit functions". Is there…

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## [How to get shader source for an actor](https://discourse.vtk.org/t/how-to-get-shader-source-for-an-actor/8408)

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**Author:** [@BlueKnight7](https://discourse.vtk.org/u/BlueKnight7)\
**Replies:** 13\
**Last updated:** [May 6, 2022, 2:20pm UTC](https://discourse.vtk.org/t/how-to-get-shader-source-for-an-actor/8408 "2022-05-06T14:20:03Z")

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I know from the nightly build documentation for 9.1 that I can use the GetSource function of vtkShader to retrieve the source (as a string) for the shader. Or, at least I hope that I can. I also know from the examples t…

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## [vtk+DearImGui integration through vtkGenericOpenGLRenderWindow](https://discourse.vtk.org/t/vtk-dearimgui-integration-through-vtkgenericopenglrenderwindow/4424)

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**Author:** [@jaswantp](https://discourse.vtk.org/u/jaswantp)\
**Replies:** 14\
**Last updated:** [May 6, 2022, 4:06am UTC](https://discourse.vtk.org/t/vtk-dearimgui-integration-through-vtkgenericopenglrenderwindow/4424 "2022-05-06T04:06:58Z")

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I made this post to help ImGui/3rd party UI users who wish to display VTK content in an externally provided context(glad/glbindings/…) and (or) windowing system (glfw/…) or DearImGUI, Nuklear, etc. So far, there is only…

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## [vtkImageData to png](https://discourse.vtk.org/t/vtkimagedata-to-png/8418)

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**Author:** [@s195t](https://discourse.vtk.org/u/s195t)\
**Replies:** 3\
**Last updated:** [May 4, 2022, 1:21pm UTC](https://discourse.vtk.org/t/vtkimagedata-to-png/8418 "2022-05-04T13:21:15Z")

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Dear everyone, I would like to export a vtkImageData of 500x500 cells to a png picture of exactly 500x500 pixel resolution. In this way, every pixel should be approximately corresponding to a cell. This means fitting m…

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## [VTK-examples FrogSlice](https://discourse.vtk.org/t/vtk-examples-frogslice/8364)

<div class="topic-metadata">

**Author:** [@Chris9810](https://discourse.vtk.org/u/Chris9810)\
**Replies:** 2\
**Last updated:** [May 4, 2022, 11:03am UTC](https://discourse.vtk.org/t/vtk-examples-frogslice/8364 "2022-05-04T11:03:50Z")

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Hi, I’m a beginner about VTK. I want to learn the FrogSlice-example in VTK website. The example provides C++ code and CMakeList.txt, but no raw image data. I would greatly appreciate it if anyone could tell me about ho…

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## [vtkActor::SetUserMatrix make the vtkPolyData incorrect](https://discourse.vtk.org/t/vtkactor-setusermatrix-make-the-vtkpolydata-incorrect/8417)

<div class="topic-metadata">

**Author:** [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)\
**Replies:** 1\
**Last updated:** [May 3, 2022, 7:14pm UTC](https://discourse.vtk.org/t/vtkactor-setusermatrix-make-the-vtkpolydata-incorrect/8417 "2022-05-03T19:14:09Z")

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I am using vtkContourFilter in my application, and the result is correct: Then, I use vtkActor::SetUserMatrix to correct the direction, and my code is: double ele\[16\] = { 1, 0, 0, 0, 0, -1, 0, 0, 0, 0, 1, 0, …

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## [MultiSlice intersection](https://discourse.vtk.org/t/multislice-intersection/8375)

<div class="topic-metadata">

**Author:** [@ksmith](https://discourse.vtk.org/u/ksmith)\
**Replies:** 2\
**Last updated:** [May 3, 2022, 11:27am UTC](https://discourse.vtk.org/t/multislice-intersection/8375 "2022-05-03T11:27:39Z")

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I have a multi slice model similar to this example and I’d like to have clear intersection lines showing between the three planes. How can I achieve this?

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