# Latest

**URL:** https://discourse.vtk.org/latest.md?page=218

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

**Page:** 219

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## [how to add a tag to an created actor](https://discourse.vtk.org/t/how-to-add-a-tag-to-an-created-actor/2998)

<div class="topic-metadata">

**Author:** [@xuexl](https://discourse.vtk.org/u/xuexl)\
**Replies:** 3\
**Last updated:** [April 10, 2020, 11:49am UTC](https://discourse.vtk.org/t/how-to-add-a-tag-to-an-created-actor/2998 "2020-04-10T11:49:54Z")

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using “vtkSphereSource”, I have added some spheres, and i want to delete some of them that clicked. so, how to distinguish them from others. using “vtkCellPicker”, i can get the actor that clicked, but i need a check t…

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## [vtkCellArray updates](https://discourse.vtk.org/t/vtkcellarray-updates/3007)

<div class="topic-metadata">

**Author:** [@kayarre](https://discourse.vtk.org/u/kayarre)\
**Replies:** 0\
**Last updated:** [April 9, 2020, 9:03pm UTC](https://discourse.vtk.org/t/vtkcellarray-updates/3007 "2020-04-09T21:03:08Z")

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based on changes from: Upcoming changes to vtkCellArray I have some code I am trying to update to the latest VTK, and I think I am running in an issue with this new implementation. vtkPolyData is subclassed and has t…

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## [In vtk.js, How to mark the outline with special color in volume drawing](https://discourse.vtk.org/t/in-vtk-js-how-to-mark-the-outline-with-special-color-in-volume-drawing/3011)

<div class="topic-metadata">

**Author:** [@huatianyu](https://discourse.vtk.org/u/huatianyu)\
**Replies:** 0\
**Last updated:** [April 10, 2020, 1:42am UTC](https://discourse.vtk.org/t/in-vtk-js-how-to-mark-the-outline-with-special-color-in-volume-drawing/3011 "2020-04-10T01:42:31Z")

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The current case is only to modify the grayscale of contour points into inverse color, but the display is still not clear, how to make the contour look clearer?For example, red, do I need to make these points into plan…

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## [How to create a point in vtk?](https://discourse.vtk.org/t/how-to-create-a-point-in-vtk/2992)

<div class="topic-metadata">

**Author:** [@NeuZhangQiang](https://discourse.vtk.org/u/NeuZhangQiang)\
**Replies:** 2\
**Last updated:** [April 10, 2020, 2:21am UTC](https://discourse.vtk.org/t/how-to-create-a-point-in-vtk/2992 "2020-04-10T02:21:15Z")

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VTK is too complicate… I want to find the connectivity region around a point, and I want to use vtkImageConnectivityFilter. The code should be: vtkSmartPointer\<vtkImageConnectivityFilter\> connectivityFilter = vtkSmart…

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## [Minimum CMake version](https://discourse.vtk.org/t/minimum-cmake-version/2867)

<div class="topic-metadata">

**Author:** [@ben.boeckel](https://discourse.vtk.org/u/ben.boeckel)\
**Replies:** 13\
**Last updated:** [April 10, 2020, 2:11am UTC](https://discourse.vtk.org/t/minimum-cmake-version/2867 "2020-04-10T02:11:30Z")

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Hi, In order to support Intel MPI better, I’d like to bump the FindMPI in VTK to the version that is provided by CMake 3.17. However, some of this logic is only available in CMake 3.12 (namely the SHELL: syntax for link…

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## [Simple image appplication..](https://discourse.vtk.org/t/simple-image-appplication/3006)

<div class="topic-metadata">

**Author:** [@kalpathi](https://discourse.vtk.org/u/kalpathi)\
**Replies:** 1\
**Last updated:** [April 9, 2020, 8:25pm UTC](https://discourse.vtk.org/t/simple-image-appplication/3006 "2020-04-09T20:25:06Z")

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I have to develop a small image application - reading in a sequence of images(volume) and doing some simple interactive image processing on each of them to identify some features. The breadth of classes in VTK is vast a…

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## [Anti-aliasing issues with Python VTK and Qt](https://discourse.vtk.org/t/anti-aliasing-issues-with-python-vtk-and-qt/2520)

<div class="topic-metadata">

**Author:** [@ian.liu88](https://discourse.vtk.org/u/ian.liu88)\
**Replies:** 3\
**Last updated:** [April 9, 2020, 3:00pm UTC](https://discourse.vtk.org/t/anti-aliasing-issues-with-python-vtk-and-qt/2520 "2020-04-09T15:00:38Z")

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The following Gist contains two simple VTK examples: The qt\_ex.py example runs VTK inside a Qt window, while the vtk\_ex.py runs a pure VTK window. The problem I’m facing is that the Qt version has no anti-alias. See t…

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## [My contour from vtkContourFilter doesn't show up ... but the vtkStructuredGridOutline does ...](https://discourse.vtk.org/t/my-contour-from-vtkcontourfilter-doesnt-show-up-but-the-vtkstructuredgridoutline-does/3002)

<div class="topic-metadata">

**Author:** [@cousinitt](https://discourse.vtk.org/u/cousinitt)\
**Replies:** 0\
**Last updated:** [April 9, 2020, 2:58pm UTC](https://discourse.vtk.org/t/my-contour-from-vtkcontourfilter-doesnt-show-up-but-the-vtkstructuredgridoutline-does/3002 "2020-04-09T14:58:56Z")

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I created a vtkStructuredGrid, set locations for the points, created a vtkDoubleArray containing the distance from the point (50, 0, 0), and tried to make a contour of the points that were 50 units away. I’m sure that I’…

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## [How to set the size of resliced image in vtkImageReslice ??](https://discourse.vtk.org/t/how-to-set-the-size-of-resliced-image-in-vtkimagereslice/2990)

<div class="topic-metadata">

**Author:** [@NeuZhangQiang](https://discourse.vtk.org/u/NeuZhangQiang)\
**Replies:** 0\
**Last updated:** [April 9, 2020, 1:32am UTC](https://discourse.vtk.org/t/how-to-set-the-size-of-resliced-image-in-vtkimagereslice/2990 "2020-04-09T01:32:04Z")

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Currently, I need to reslice a 2D image from a 3D volume image. The vtkImageReslice is a good choice. My code is: vtkSmartPointer\<vtkImageReslice\> resliceOperation = vtkSmartPointer\<vtkImageReslice\>::New(); resliceOper…

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## [Updating a vtkSpline](https://discourse.vtk.org/t/updating-a-vtkspline/2986)

<div class="topic-metadata">

**Author:** [@prater27](https://discourse.vtk.org/u/prater27)\
**Replies:** 0\
**Last updated:** [April 8, 2020, 6:40pm UTC](https://discourse.vtk.org/t/updating-a-vtkspline/2986 "2020-04-08T18:40:46Z")

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Hi! Thank you in advance for your support. I have implemented a small tool capable of doing simple animations from external data. The external data are a list of lines containing every line: time, 3D position and a Q…

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## [user matrix on vtk reslice cursor widget](https://discourse.vtk.org/t/user-matrix-on-vtk-reslice-cursor-widget/2981)

<div class="topic-metadata">

**Author:** [@tom1](https://discourse.vtk.org/u/tom1)\
**Replies:** 5\
**Last updated:** [April 8, 2020, 1:39pm UTC](https://discourse.vtk.org/t/user-matrix-on-vtk-reslice-cursor-widget/2981 "2020-04-08T13:39:32Z")

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Hi, VTK experts. I am trying to setup a reslice cursor widget with a user matrix. Currently, I am trying to assign the user matrix to the reslice cursor line representation, which I set to the rsc widget. In result, t…

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## [unstructured grid with approximated spheres as cells](https://discourse.vtk.org/t/unstructured-grid-with-approximated-spheres-as-cells/2974)

<div class="topic-metadata">

**Author:** [@cobo](https://discourse.vtk.org/u/cobo)\
**Replies:** 5\
**Last updated:** [April 8, 2020, 10:18am UTC](https://discourse.vtk.org/t/unstructured-grid-with-approximated-spheres-as-cells/2974 "2020-04-08T10:18:06Z")

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Trying to generate an “unstructured grid” with some kind of sphere approximation as “cells” - and so far this is the best I could achieve: This is a “triquadratic hexahedron”, with all the reference points at the same…

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## [vtkPointInterpolator doesn't work, if the scalar array of the source data does not have a name](https://discourse.vtk.org/t/vtkpointinterpolator-doesnt-work-if-the-scalar-array-of-the-source-data-does-not-have-a-name/2979)

<div class="topic-metadata">

**Author:** [@Yue\_JIN](https://discourse.vtk.org/u/Yue_JIN)\
**Replies:** 1\
**Last updated:** [April 8, 2020, 6:12am UTC](https://discourse.vtk.org/t/vtkpointinterpolator-doesnt-work-if-the-scalar-array-of-the-source-data-does-not-have-a-name/2979 "2020-04-08T06:12:53Z")

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It may be a bug? This problem is not stated in document.

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## [VTK 9.0.0.rc2](https://discourse.vtk.org/t/vtk-9-0-0-rc2/2977)

<div class="topic-metadata">

**Author:** [@TJ\_Corona](https://discourse.vtk.org/u/TJ_Corona)\
**Replies:** 1\
**Last updated:** [April 8, 2020, 3:02am UTC](https://discourse.vtk.org/t/vtk-9-0-0-rc2/2977 "2020-04-08T03:02:14Z")

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The VTK maintenance team is happy to announce that VTK 9.0.0 RC2 is available for testing! You can find the source, data and documentation tarballs here . Take a look at the VTK wiki for a complete list of API changes…

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## [9.0.0.rc1 CMake policy error (using CMake 3.9.3)](https://discourse.vtk.org/t/9-0-0-rc1-cmake-policy-error-using-cmake-3-9-3/2976)

<div class="topic-metadata">

**Author:** [@biagas](https://discourse.vtk.org/u/biagas)\
**Replies:** 2\
**Last updated:** [April 7, 2020, 5:17pm UTC](https://discourse.vtk.org/t/9-0-0-rc1-cmake-policy-error-using-cmake-3-9-3/2976 "2020-04-07T17:17:40Z")

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Linux, rhel7, CMake 3.9.3, I passed no args to CMake, and configure fails with this error: CMake Error at ThirdParty/hdf5/CMakeLists.txt:2 (cmake\_policy): Policy “CMP0074” is not known to this version of CMake.

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## [How to extend the Java wrapper API?](https://discourse.vtk.org/t/how-to-extend-the-java-wrapper-api/2970)

<div class="topic-metadata">

**Author:** [@mat127](https://discourse.vtk.org/u/mat127)\
**Replies:** 7\
**Last updated:** [April 7, 2020, 5:08pm UTC](https://discourse.vtk.org/t/how-to-extend-the-java-wrapper-api/2970 "2020-04-07T17:08:03Z")

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Hello, I have realized that VTK Java wrapper API is a subset of the full VTK API. How is the wrapper generated and how is the selection of what will be available in the Java wrapper done? Is it possible to add a partic…

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## [Testing merge requests](https://discourse.vtk.org/t/testing-merge-requests/2947)

<div class="topic-metadata">

**Author:** [@utkarshayachit](https://discourse.vtk.org/u/utkarshayachit)\
**Replies:** 8\
**Last updated:** [April 7, 2020, 3:40pm UTC](https://discourse.vtk.org/t/testing-merge-requests/2947 "2020-04-07T15:40:59Z")

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should we recommend use Do: test --merged when testing older branches esp. those that are being backported to the release? I suspect that is one the reasons why dashboards are taking too long of late.

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## [Multiplanar Reconstruction(MPR) for CORONAL images](https://discourse.vtk.org/t/multiplanar-reconstruction-mpr-for-coronal-images/2973)

<div class="topic-metadata">

**Author:** [@Satwik](https://discourse.vtk.org/u/Satwik)\
**Replies:** 0\
**Last updated:** [April 7, 2020, 10:32am UTC](https://discourse.vtk.org/t/multiplanar-reconstruction-mpr-for-coronal-images/2973 "2020-04-07T10:32:41Z")

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Hello everyone, I’m having images which are actually CORONAL acquired. How can i get axial and sagittal transformation matrix like angle of rotation or direction of rotation from CORONAL acquired images. Regards, Sat…

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## [VTK conflict with QT webengine...? \[closed\]](https://discourse.vtk.org/t/vtk-conflict-with-qt-webengine-closed/2971)

<div class="topic-metadata">

**Author:** [@rdbrn](https://discourse.vtk.org/u/rdbrn)\
**Replies:** 1\
**Last updated:** [April 7, 2020, 6:54am UTC](https://discourse.vtk.org/t/vtk-conflict-with-qt-webengine-closed/2971 "2020-04-07T06:54:41Z")

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I ran into quite an obscure problem with the combination of VTK and a Qt WebEngine. Not sure if it is a QT or a VTK problem (or both). To avoid double posts I link here to the post on the qt forum: https://forum.qt.io/t…

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## [set up pipeline and only change the input data](https://discourse.vtk.org/t/set-up-pipeline-and-only-change-the-input-data/2954)

<div class="topic-metadata">

**Author:** [@kayarre](https://discourse.vtk.org/u/kayarre)\
**Replies:** 4\
**Last updated:** [April 6, 2020, 9:54pm UTC](https://discourse.vtk.org/t/set-up-pipeline-and-only-change-the-input-data/2954 "2020-04-06T21:54:50Z")

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I am very used to the idea of pipelines in vtk, but I end up follow this convention for a loop I have always been unclear on the proper way to use them, some filters allow and others don’t? can the pipelines recursivel…

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## [Backfaces showing through & other (z-buffer?) oddities when using vtk8.2](https://discourse.vtk.org/t/backfaces-showing-through-other-z-buffer-oddities-when-using-vtk8-2/2939)

<div class="topic-metadata">

**Author:** [@geoffw](https://discourse.vtk.org/u/geoffw)\
**Replies:** 4\
**Last updated:** [April 6, 2020, 6:07pm UTC](https://discourse.vtk.org/t/backfaces-showing-through-other-z-buffer-oddities-when-using-vtk8-2/2939 "2020-04-06T18:07:27Z")

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Hi, We have recently migrated from vtk8.1 to vtk8.2. We immediately noticed some z-fighting going on between 3d geometries and 2d regions that are “attached” to the surfaces (each polydata has a separate actor). In vtk8…

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## [vtkXRenderWindowInteractor: ProcessEvents does not work](https://discourse.vtk.org/t/vtkxrenderwindowinteractor-processevents-does-not-work/2969)

<div class="topic-metadata">

**Author:** [@TomLKoller](https://discourse.vtk.org/u/TomLKoller)\
**Replies:** 6\
**Last updated:** [April 6, 2020, 6:00pm UTC](https://discourse.vtk.org/t/vtkxrenderwindowinteractor-processevents-does-not-work/2969 "2020-04-06T18:00:35Z")

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The ProcessEvents() method of vtkRenderWindowInteractor can be used to implement custom event loops. I used the method on a Ubuntu LTs 18.04 Machine with vtk 9. My setup worked when i called the Start() method but not …

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## [VTK Gradient Filter](https://discourse.vtk.org/t/vtk-gradient-filter/2961)

<div class="topic-metadata">

**Author:** [@RSwn](https://discourse.vtk.org/u/RSwn)\
**Replies:** 6\
**Last updated:** [April 6, 2020, 3:22pm UTC](https://discourse.vtk.org/t/vtk-gradient-filter/2961 "2020-04-06T15:22:45Z")

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I am using the vtkGradientFilter in Python in order to compute velocity gradients from a vtkUnstructuredGrid file with a snippet shown below. However, when visualised in Paraview the results seem quite blocky and coarse.…

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## [Use VTK](https://discourse.vtk.org/t/use-vtk/2943)

<div class="topic-metadata">

**Author:** [@1117](https://discourse.vtk.org/u/1117)\
**Replies:** 2\
**Last updated:** [April 6, 2020, 1:48pm UTC](https://discourse.vtk.org/t/use-vtk/2943 "2020-04-06T13:48:33Z")

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Hi, I am new in VTK and Python. I need to show a 3D image in python with VTK. This file is a nrrd file. please help me. Thanks

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## [How to fix the font actor size, that is, the font size does not change when the camera distance is changed](https://discourse.vtk.org/t/how-to-fix-the-font-actor-size-that-is-the-font-size-does-not-change-when-the-camera-distance-is-changed/2965)

<div class="topic-metadata">

**Author:** [@kknnnyy](https://discourse.vtk.org/u/kknnnyy)\
**Replies:** 3\
**Last updated:** [April 6, 2020, 12:33pm UTC](https://discourse.vtk.org/t/how-to-fix-the-font-actor-size-that-is-the-font-size-does-not-change-when-the-camera-distance-is-changed/2965 "2020-04-06T12:33:29Z")

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I need to make the text face the camera, so I tried two methods vtkVectorText + vtkFollower This method cannot have a fixed font size like vtkTextActor vtkTextActor It is a vtkActor2D object, this method can not set …

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## [How to use VTK to realize volume rendering in the application based on OpenSceneGraph](https://discourse.vtk.org/t/how-to-use-vtk-to-realize-volume-rendering-in-the-application-based-on-openscenegraph/2327)

<div class="topic-metadata">

**Author:** [@yuhuimoon](https://discourse.vtk.org/u/yuhuimoon)\
**Replies:** 5\
**Last updated:** [April 6, 2020, 12:05pm UTC](https://discourse.vtk.org/t/how-to-use-vtk-to-realize-volume-rendering-in-the-application-based-on-openscenegraph/2327 "2020-04-06T12:05:11Z")

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I’m a beginner of VTK. My 3D application is based on OpenSceneGraph(OSG). Now I want to add volume rendering into the application so that it can convert CT/MRI images to 3D scene. But the volume rendering of OSG is too s…

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## [Segmentation on 3D DICOM ultrasound fetus image](https://discourse.vtk.org/t/segmentation-on-3d-dicom-ultrasound-fetus-image/2953)

<div class="topic-metadata">

**Author:** [@RomyM](https://discourse.vtk.org/u/RomyM)\
**Replies:** 1\
**Last updated:** [April 6, 2020, 11:36am UTC](https://discourse.vtk.org/t/segmentation-on-3d-dicom-ultrasound-fetus-image/2953 "2020-04-06T11:36:48Z")

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Hello, I am new to VTK (and ITK) and I succesfully visualized with volume rendering my 3D dataset. However, I now only want to show the fetus and the placental volume. So I want to segment the fetus and the placenta, an…

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## [Development of a new PVTU writer to reduce the number of files](https://discourse.vtk.org/t/development-of-a-new-pvtu-writer-to-reduce-the-number-of-files/2926)

<div class="topic-metadata">

**Author:** [@GonzaloS](https://discourse.vtk.org/u/GonzaloS)\
**Replies:** 2\
**Last updated:** [April 6, 2020, 11:11am UTC](https://discourse.vtk.org/t/development-of-a-new-pvtu-writer-to-reduce-the-number-of-files/2926 "2020-04-06T11:11:22Z")

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Hi everyone, I know that a lot of people have problems when writing PVTU files using the vtkXMLPUnstructuredGridWriter object due to the fact that each processor writes a VTU file per PVTU output file. This means that …

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## [render 2D content in QVTKOpenGLNativeWidget](https://discourse.vtk.org/t/render-2d-content-in-qvtkopenglnativewidget/2964)

<div class="topic-metadata">

**Author:** [@yuhuimoon](https://discourse.vtk.org/u/yuhuimoon)\
**Replies:** 4\
**Last updated:** [April 6, 2020, 8:32am UTC](https://discourse.vtk.org/t/render-2d-content-in-qvtkopenglnativewidget/2964 "2020-04-06T08:32:29Z")

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I have a question puzzles me for a long time. The class FormResliceViewer derives from QVTKOpenGLNativeWidget. vtkResliceImageViewer is used, with SetRenderWindow() by the FormResliceViewer object. Image reslice can be …

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## [Using vtkChartXY with vtkMFCWindow](https://discourse.vtk.org/t/using-vtkchartxy-with-vtkmfcwindow/2959)

<div class="topic-metadata">

**Author:** [@dwventer](https://discourse.vtk.org/u/dwventer)\
**Replies:** 1\
**Last updated:** [April 6, 2020, 4:24am UTC](https://discourse.vtk.org/t/using-vtkchartxy-with-vtkmfcwindow/2959 "2020-04-06T04:24:45Z")

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So I found plenty of examples where I can plot a chart using something like the vtkChartXY and vtkContextView object. Something like “pvtContextViewChart-\>GetScene()-\>AddItem(pvtChart);” is needed. Can something please …

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