# Support

**URL:** https://discourse.vtk.org/c/support/6.md?page=140

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

**Page:** 141

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## [Controlled Surface Triangulation](https://discourse.vtk.org/t/controlled-surface-triangulation/2526)

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**Author:** [@ChristopherWaters](https://discourse.vtk.org/u/ChristopherWaters)\
**Replies:** 12\
**Last updated:** [February 13, 2020, 6:03am UTC](https://discourse.vtk.org/t/controlled-surface-triangulation/2526 "2020-02-13T06:03:06Z")

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Currently: I have a VTK program that allows you to build and edit meshes. What I Want to Achieve: I would like to apply triangulation to the surfaces of the meshes for FEM (meshes are unstructured grids) Have the …

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## [Plotting 2D Isosurface in Python](https://discourse.vtk.org/t/plotting-2d-isosurface-in-python/2577)

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**Author:** [@RSwn](https://discourse.vtk.org/u/RSwn)\
**Replies:** 2\
**Last updated:** [February 12, 2020, 8:13pm UTC](https://discourse.vtk.org/t/plotting-2d-isosurface-in-python/2577 "2020-02-12T20:13:23Z")

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I am looking to plot a 2D isosurface using VTK in Python. I am trying to visualise the Q-Criterion in Paraview but am looking to build the isosurface into the file rather than using the Paraview option. I couldn’t find m…

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## [Changing the Scalar Values of a vtkImageReslice Object in a Pipeline](https://discourse.vtk.org/t/changing-the-scalar-values-of-a-vtkimagereslice-object-in-a-pipeline/2584)

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**Author:** [@MichelleKline](https://discourse.vtk.org/u/MichelleKline)\
**Replies:** 2\
**Last updated:** [February 12, 2020, 3:36pm UTC](https://discourse.vtk.org/t/changing-the-scalar-values-of-a-vtkimagereslice-object-in-a-pipeline/2584 "2020-02-12T15:36:27Z")

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Hello, I am using vtkImageReslice to reslice a volume. I do the reslicing by controlling the resliceAxes of the vtkImageReslice object. Each time a “take a new slice” (ie, change the resliceAxes), I perform some calcu…

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## [I can't find QVTKOpenGLWidget in VTK 7.1.1](https://discourse.vtk.org/t/i-cant-find-qvtkopenglwidget-in-vtk-7-1-1/2589)

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**Author:** [@embeddedmz](https://discourse.vtk.org/u/embeddedmz)\
**Replies:** 0\
**Last updated:** [February 12, 2020, 12:13pm UTC](https://discourse.vtk.org/t/i-cant-find-qvtkopenglwidget-in-vtk-7-1-1/2589 "2020-02-12T12:13:54Z")

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Hi VTK Experts, The title says it all : I can’t find QVTKOpenGLWidget in VTK 7.1.1 sources. Is that normal ? Thanks !

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## [Vertical stripe for some Sample Distance values](https://discourse.vtk.org/t/vertical-stripe-for-some-sample-distance-values/2574)

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**Author:** [@Ana\_Margarida\_Mota](https://discourse.vtk.org/u/Ana_Margarida_Mota)\
**Replies:** 6\
**Last updated:** [February 12, 2020, 11:44am UTC](https://discourse.vtk.org/t/vertical-stripe-for-some-sample-distance-values/2574 "2020-02-12T11:44:27Z")

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Dear colleagues, I am facing a problem when changing the sample distance value. For certain values of sample distance, defined with SetSampleDistance (), a vertical stripe that crosses the entire object appears when I …

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## [How do I modify the selection box in vtkInteractor StyleRubberBandPick to a selection circle?](https://discourse.vtk.org/t/how-do-i-modify-the-selection-box-in-vtkinteractor-stylerubberbandpick-to-a-selection-circle/2586)

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**Author:** [@ymmx](https://discourse.vtk.org/u/ymmx)\
**Replies:** 0\
**Last updated:** [February 12, 2020, 7:48am UTC](https://discourse.vtk.org/t/how-do-i-modify-the-selection-box-in-vtkinteractor-stylerubberbandpick-to-a-selection-circle/2586 "2020-02-12T07:48:29Z")

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I’m wondering if it is possible to modify the shape of the box that is displayed when I pick an area with ‘r’? I would like it to be circle where the center is the position the mouse was at when I pressed the mouse and t…

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## [How can I add a observer to a vtk Interactor Style Rubber Band Pick class?](https://discourse.vtk.org/t/how-can-i-add-a-observer-to-a-vtk-interactor-style-rubber-band-pick-class/2532)

<div class="topic-metadata">

**Author:** [@ymmx](https://discourse.vtk.org/u/ymmx)\
**Replies:** 4\
**Last updated:** [February 12, 2020, 7:39am UTC](https://discourse.vtk.org/t/how-can-i-add-a-observer-to-a-vtk-interactor-style-rubber-band-pick-class/2532 "2020-02-12T07:39:04Z")

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I’m trying to add an Observer to a class that inherit from vtkInteractorStyleRubberBandPick. My goal is to trigger a function when I finished to make a bouding box on the screen with the key ‘r’. The issue is I don’t f…

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## [vtkAngleWidget set label to a fixed size does not work](https://discourse.vtk.org/t/vtkanglewidget-set-label-to-a-fixed-size-does-not-work/2578)

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**Author:** [@zandarina](https://discourse.vtk.org/u/zandarina)\
**Replies:** 0\
**Last updated:** [February 11, 2020, 2:33pm UTC](https://discourse.vtk.org/t/vtkanglewidget-set-label-to-a-fixed-size-does-not-work/2578 "2020-02-11T14:33:16Z")

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Dear all, I want to set the text size of the angle arc to a size but it does not work. The size is very small and it is not visible. I have tried several options but only the sace waorks and i want a fixed size as the d…

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## [transform RGBA to RGB after blending](https://discourse.vtk.org/t/transform-rgba-to-rgb-after-blending/2576)

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**Author:** [@rprueckl](https://discourse.vtk.org/u/rprueckl)\
**Replies:** 0\
**Last updated:** [February 10, 2020, 4:35pm UTC](https://discourse.vtk.org/t/transform-rgba-to-rgb-after-blending/2576 "2020-02-10T16:35:42Z")

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I want to achieve a fairly simple operation in VTK. My starting point are several 2D images (same dimensions) that I want blend together over a black background. All images have alpha channels and some (semi)transparent …

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## [Run VTK example in Qt](https://discourse.vtk.org/t/run-vtk-example-in-qt/2569)

<div class="topic-metadata">

**Author:** [@kerim](https://discourse.vtk.org/u/kerim)\
**Replies:** 5\
**Last updated:** [February 10, 2020, 3:32pm UTC](https://discourse.vtk.org/t/run-vtk-example-in-qt/2569 "2020-02-10T15:32:56Z")

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Hi, I’m beginner at VTK and I need help to start working with that. I built VTK library. I can run examples from official site. But to run them I add the following code: #include \<vtkAutoInit.h\> VTK\_MODULE\_INIT(vtkR…

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## [Pick and highlight glyphs.](https://discourse.vtk.org/t/pick-and-highlight-glyphs/1613)

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**Author:** [@Mskovmand](https://discourse.vtk.org/u/Mskovmand)\
**Replies:** 5\
**Last updated:** [February 10, 2020, 6:45am UTC](https://discourse.vtk.org/t/pick-and-highlight-glyphs/1613 "2020-02-10T06:45:09Z")

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Firstly, I’m still fairly new at VTK, I’m doing the best I can :slight\_smile: I have a scene illustrating points as glyphs. I want to be able to pick and highlight each glyph individually. I have implemented the intera…

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## [Convert vtkPropPicker value to vtkVoxel values](https://discourse.vtk.org/t/convert-vtkproppicker-value-to-vtkvoxel-values/2549)

<div class="topic-metadata">

**Author:** [@flaviu2](https://discourse.vtk.org/u/flaviu2)\
**Replies:** 6\
**Last updated:** [February 9, 2020, 9:50am UTC](https://discourse.vtk.org/t/convert-vtkproppicker-value-to-vtkvoxel-values/2549 "2020-02-09T09:50:04Z")

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I am trying to know the min\_voxel / max\_voxel for vtkImageConnectivityFilter::SetSizeRange for bones, and I don’t know from where I taken … and I thinking (maybe is stupid) to get those values from a vtkPropPicker … it i…

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## [Ospray Material Library problem with mtl file](https://discourse.vtk.org/t/ospray-material-library-problem-with-mtl-file/2558)

<div class="topic-metadata">

**Author:** [@gilcu2](https://discourse.vtk.org/u/gilcu2)\
**Replies:** 2\
**Last updated:** [February 8, 2020, 6:34am UTC](https://discourse.vtk.org/t/ospray-material-library-problem-with-mtl-file/2558 "2020-02-08T06:34:35Z")

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I am using vtkOSPRayMaterialLibrary to read an mtl file but all the shaded variables for any material return (1,1,1) and these are not the values in the mtl. Attached source and mtl file. Am I doing something wrong? T…

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## [How to set a background on a vtkCaptionWidget or a vtkCaptionActor2D](https://discourse.vtk.org/t/how-to-set-a-background-on-a-vtkcaptionwidget-or-a-vtkcaptionactor2d/2565)

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**Author:** [@jean](https://discourse.vtk.org/u/jean)\
**Replies:** 0\
**Last updated:** [February 7, 2020, 3:30pm UTC](https://discourse.vtk.org/t/how-to-set-a-background-on-a-vtkcaptionwidget-or-a-vtkcaptionactor2d/2565 "2020-02-07T15:30:16Z")

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Hi, I have played around to format a vtkCaptionActor2D, and found a hacky way for displaying a background. The Border if off and what we see is the frame from the CaptionTextProperty with added spaces for padding: ac…

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## [Topology Representations](https://discourse.vtk.org/t/topology-representations/2564)

<div class="topic-metadata">

**Author:** [@Luis\_Carlos\_Carneiro](https://discourse.vtk.org/u/Luis_Carlos_Carneiro)\
**Replies:** 0\
**Last updated:** [February 7, 2020, 12:46pm UTC](https://discourse.vtk.org/t/topology-representations/2564 "2020-02-07T12:46:47Z")

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Dear All, Which mesh topology VTK supports (e.g Face-Vertex Meshes, Winged-Edge Mesches) for image editing or rendering? Are there some lossless conversion functions between these topologies? Thanks, Luis Gonçalves

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## [Representation of Points in Polydata using PointGaussianMapper.](https://discourse.vtk.org/t/representation-of-points-in-polydata-using-pointgaussianmapper/2562)

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**Author:** [@koushik](https://discourse.vtk.org/u/koushik)\
**Replies:** 0\
**Last updated:** [February 7, 2020, 10:50am UTC](https://discourse.vtk.org/t/representation-of-points-in-polydata-using-pointgaussianmapper/2562 "2020-02-07T10:50:22Z")

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Hi, I have a polydata which contains points and scalar values at those points.(Link for polydata : https://drive.google.com/file/d/19kt16tYHnioucDjqRAOpSy8OAgkLYIAM/view?usp=sharing). The below image shows the polydata…

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## [Orientation Widget "Padding"](https://discourse.vtk.org/t/orientation-widget-padding/2546)

<div class="topic-metadata">

**Author:** [@ChristopherWaters](https://discourse.vtk.org/u/ChristopherWaters)\
**Replies:** 10\
**Last updated:** [February 7, 2020, 4:40am UTC](https://discourse.vtk.org/t/orientation-widget-padding/2546 "2020-02-07T04:40:14Z")

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Currently: I have implemented an orientation widget into my application using: orientationWidget = vtkSmartPointer\<vtkOrientationMarkerWidget\>::New(); axes = vtkSmartPointer\<vtkAxesActor\>::New(); orientationWidget-\>Se…

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## [Voxel size of a tooth](https://discourse.vtk.org/t/voxel-size-of-a-tooth/2552)

<div class="topic-metadata">

**Author:** [@flaviu2](https://discourse.vtk.org/u/flaviu2)\
**Replies:** 1\
**Last updated:** [February 6, 2020, 4:20am UTC](https://discourse.vtk.org/t/voxel-size-of-a-tooth/2552 "2020-02-06T04:20:26Z")

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Hello. I am come here with a simple question: how can I know the voxel size of a tooth from a vtkVolume (dentition CT scan) ? I don’t know from where to take this value … I need it for computing the size range in order t…

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## [Touchscreen Pan Gesture on a Qt-QML application](https://discourse.vtk.org/t/touchscreen-pan-gesture-on-a-qt-qml-application/2535)

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**Author:** [@Synfony](https://discourse.vtk.org/u/Synfony)\
**Replies:** 13\
**Last updated:** [February 5, 2020, 10:32pm UTC](https://discourse.vtk.org/t/touchscreen-pan-gesture-on-a-qt-qml-application/2535 "2020-02-05T22:32:17Z")

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Hi, First of all, I tried to build the TouchGestureViewer example (from https://gitlab.kitware.com/vtk/vtk/tree/master/Examples/GUI/Qt/TouchGestureViewer) using VTK8.2.0 and Qt5.12.6 on Windows10(64 bit) surface. But I…

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## [Read a .vtk file inside a .tar archive without extracting the files](https://discourse.vtk.org/t/read-a-vtk-file-inside-a-tar-archive-without-extracting-the-files/2554)

<div class="topic-metadata">

**Author:** [@DFlyer](https://discourse.vtk.org/u/DFlyer)\
**Replies:** 0\
**Last updated:** [February 5, 2020, 6:20pm UTC](https://discourse.vtk.org/t/read-a-vtk-file-inside-a-tar-archive-without-extracting-the-files/2554 "2020-02-05T18:20:12Z")

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Hello, I need to read a .vtk file and I do it by reader = vtk.vtkStructuredPointsReader() reader.SetFileName(file) My files are mostly inside a .tar archive, along with vtk file there are lot other files inside. I ca…

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## [removing segments of MRI 3D model](https://discourse.vtk.org/t/removing-segments-of-mri-3d-model/2550)

<div class="topic-metadata">

**Author:** [@Tracy\_Nk](https://discourse.vtk.org/u/Tracy_Nk)\
**Replies:** 1\
**Last updated:** [February 5, 2020, 3:46pm UTC](https://discourse.vtk.org/t/removing-segments-of-mri-3d-model/2550 "2020-02-05T15:46:10Z")

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Hi, I’m aware that I can use VTK to get a 3D visualisation of an MRI DICOM data set, however, my next goal is to be able to remove parts of the 3D brain model so that I can focus on and only see a specific part of the br…

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## [initialize vtkBorderWidget with the click of the mouse](https://discourse.vtk.org/t/initialize-vtkborderwidget-with-the-click-of-the-mouse/2519)

<div class="topic-metadata">

**Author:** [@zandarina](https://discourse.vtk.org/u/zandarina)\
**Replies:** 5\
**Last updated:** [February 5, 2020, 2:02pm UTC](https://discourse.vtk.org/t/initialize-vtkborderwidget-with-the-click-of-the-mouse/2519 "2020-02-05T14:02:23Z")

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Dear all, I want to obtain a ROI over an vtkimagedata (dicom) to perform certain statistics in that area (e.g., mean, std…). So i am using vtkBorderWidget. But i found out that it is always initialzed at the left bottom…

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## [Eye-Dome Lighting and Viewport](https://discourse.vtk.org/t/eye-dome-lighting-and-viewport/1249)

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**Author:** [@GuillaumeFavelier](https://discourse.vtk.org/u/GuillaumeFavelier)\
**Replies:** 6\
**Last updated:** [February 4, 2020, 11:28pm UTC](https://discourse.vtk.org/t/eye-dome-lighting-and-viewport/1249 "2020-02-04T23:28:46Z")

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In a vtkRenderWindow using multiple instances of vtkRenderer each in its own viewport, how does one can manage to enable vtkEDLShading in one renderer without whitening the others? Is this behaviour expected or did I may…

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## [What is SetSampleDimensions in vtkSampleFunction?](https://discourse.vtk.org/t/what-is-setsampledimensions-in-vtksamplefunction/2540)

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**Author:** [@stwalker](https://discourse.vtk.org/u/stwalker)\
**Replies:** 0\
**Last updated:** [February 4, 2020, 1:16pm UTC](https://discourse.vtk.org/t/what-is-setsampledimensions-in-vtksamplefunction/2540 "2020-02-04T13:16:44Z")

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Referring to the example found here: https://cmake.org/Wiki/VTK/Examples/Python/Implicit/Quadric I know that increasing the arguments SetSampleDimensions seems to increase the mesh density (I think), and generally make…

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## [Change interactor style at runtime](https://discourse.vtk.org/t/change-interactor-style-at-runtime/1985)

<div class="topic-metadata">

**Author:** [@flaviu2](https://discourse.vtk.org/u/flaviu2)\
**Replies:** 0\
**Last updated:** [October 27, 2019, 11:52am UTC](https://discourse.vtk.org/t/change-interactor-style-at-runtime/1985 "2019-10-27T11:52:51Z")

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It is possible to change the vtkRenderWindowInteractor interactor style at run time ? I have tried to change it from 2D interactor style to 3D interactor style, and is not working … and I am wonder if it is possible … I…

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## [How to reproduce vtkImageCropFilter from VTK.js in Python?](https://discourse.vtk.org/t/how-to-reproduce-vtkimagecropfilter-from-vtk-js-in-python/2533)

<div class="topic-metadata">

**Author:** [@ian.liu88](https://discourse.vtk.org/u/ian.liu88)\
**Replies:** 1\
**Last updated:** [February 3, 2020, 2:08pm UTC](https://discourse.vtk.org/t/how-to-reproduce-vtkimagecropfilter-from-vtk-js-in-python/2533 "2020-02-03T14:08:52Z")

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The following example from VTK.js website shows a Crop Filter that doesn’t seem to exist on “vanilla” VTK. How can I reproduce it with Python?

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## [Gaussian Filter and Python](https://discourse.vtk.org/t/gaussian-filter-and-python/2529)

<div class="topic-metadata">

**Author:** [@Uncheajax](https://discourse.vtk.org/u/Uncheajax)\
**Replies:** 2\
**Last updated:** [February 3, 2020, 5:55am UTC](https://discourse.vtk.org/t/gaussian-filter-and-python/2529 "2020-02-03T05:55:55Z")

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Hello, I am new to VTK. I want to load a DICOM file using VTK in python and then implement Gaussian and Median Filters with python code. Please can someone assist? I’m kinda confused as to how to go about it.

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## [How to extract the ids of the boundary points of a surface?](https://discourse.vtk.org/t/how-to-extract-the-ids-of-the-boundary-points-of-a-surface/2530)

<div class="topic-metadata">

**Author:** [@normanius](https://discourse.vtk.org/u/normanius)\
**Replies:** 2\
**Last updated:** [February 1, 2020, 7:01pm UTC](https://discourse.vtk.org/t/how-to-extract-the-ids-of-the-boundary-points-of-a-surface/2530 "2020-02-01T19:01:46Z")

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I know that it is possible to extract boundary edges using vtkFeatureEdges. See this example. The edges are returned as a new vtkPolyData consisting of one or more vtkPolyLines. However, I require the point ids of the i…

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## [vtkRenderWindow window not responding](https://discourse.vtk.org/t/vtkrenderwindow-window-not-responding/2524)

<div class="topic-metadata">

**Author:** [@Indushekhar\_Singh](https://discourse.vtk.org/u/Indushekhar_Singh)\
**Replies:** 0\
**Last updated:** [January 30, 2020, 7:51pm UTC](https://discourse.vtk.org/t/vtkrenderwindow-window-not-responding/2524 "2020-01-30T19:51:45Z")

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Hi I am using Activiz ( VTK for .NET ) version 5.8. My application is to render a real-time 3D Point cloud. My render window crashes whenever I minimize the render window or switch tab to use other applications on my PC…

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## [vtkInteractorStyleFlight: hack it to be usable?](https://discourse.vtk.org/t/vtkinteractorstyleflight-hack-it-to-be-usable/2509)

<div class="topic-metadata">

**Author:** [@banesullivan](https://discourse.vtk.org/u/banesullivan)\
**Replies:** 1\
**Last updated:** [January 28, 2020, 7:38pm UTC](https://discourse.vtk.org/t/vtkinteractorstyleflight-hack-it-to-be-usable/2509 "2020-01-28T19:38:37Z")

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Does anyone have experience using the vtkInteractorStyleFlight? It appears to not really work (no key bindings do anything) but the mouse click events will move the camera, you just cannot see where until you let off the…

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