# Development

**URL:** https://discourse.vtk.org/c/development/7.md?page=41

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

**Page:** 42

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## [CombineImages - lots of OpenGL rendering messages.](https://discourse.vtk.org/t/combineimages-lots-of-opengl-rendering-messages/4385)

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**Author:** [@amaclean](https://discourse.vtk.org/u/amaclean)\
**Replies:** 1\
**Last updated:** [October 10, 2020, 9:55pm UTC](https://discourse.vtk.org/t/combineimages-lots-of-opengl-rendering-messages/4385 "2020-10-10T21:55:28Z")

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@ken-martin, You may have some ideas here. I have been updating the VTK Examples and this example produces a huge number of OpenGL generic warnings and errors: CombineImages. An image is finally produced. The test data…

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## [Warnings in VTK regarding number of points != zero](https://discourse.vtk.org/t/warnings-in-vtk-regarding-number-of-points-zero/4384)

<div class="topic-metadata">

**Author:** [@amaclean](https://discourse.vtk.org/u/amaclean)\
**Replies:** 3\
**Last updated:** [October 10, 2020, 9:50pm UTC](https://discourse.vtk.org/t/warnings-in-vtk-regarding-number-of-points-zero/4384 "2020-10-10T21:50:34Z")

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@Charles\_Gueunet, @mwestphal, any ideas regarding this? I have been modernising/updating the vtk examples and this example seems to be highlighting an inconsistency in VTK: ImageWarp. I remember many years ago translati…

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## [Proposal to add orientation to vtkImageData- Feedback Wanted](https://discourse.vtk.org/t/proposal-to-add-orientation-to-vtkimagedata-feedback-wanted/120)

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**Author:** [@ken-martin](https://discourse.vtk.org/u/ken-martin)\
**Replies:** 46\
**Last updated:** [October 7, 2020, 3:53pm UTC](https://discourse.vtk.org/t/proposal-to-add-orientation-to-vtkimagedata-feedback-wanted/120 "2020-10-07T15:53:44Z")

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Summary: We are considering adding orientation into vtkImageData to support rotations and inversions but not shears. We are looking for feedback on the idea and the two approaches listed below. This document was created…

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## [VTK Python: disappearing lines in the reslice tool](https://discourse.vtk.org/t/vtk-python-disappearing-lines-in-the-reslice-tool/4347)

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**Author:** [@Ennio\_Bolondi](https://discourse.vtk.org/u/Ennio_Bolondi)\
**Replies:** 0\
**Last updated:** [October 4, 2020, 9:14am UTC](https://discourse.vtk.org/t/vtk-python-disappearing-lines-in-the-reslice-tool/4347 "2020-10-04T09:14:26Z")

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Hi folks, I’m writing for pointing out an issue that I’m experiencing with Vtk Python. I’m working with the “reslice” tool and, as you can see in the image below, the line actors are hidden at the begin. They only app…

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## [Move actor with keyboard arrow keys](https://discourse.vtk.org/t/move-actor-with-keyboard-arrow-keys/2045)

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**Author:** [@rai-sam](https://discourse.vtk.org/u/rai-sam)\
**Replies:** 2\
**Last updated:** [October 3, 2020, 4:48pm UTC](https://discourse.vtk.org/t/move-actor-with-keyboard-arrow-keys/2045 "2020-10-03T16:48:02Z")

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How to move actor with keyboard arrow keys events? vtkInteractorStyleTrackballActor is not suitable. vtkInteractorStyleFlight is broken. I have implemented an observer with switch cases key codes VK\_LEFT, VK\_RIGHT, VK\_…

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## [access points of a mesh](https://discourse.vtk.org/t/access-points-of-a-mesh/4321)

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**Author:** [@pierrectl](https://discourse.vtk.org/u/pierrectl)\
**Replies:** 2\
**Last updated:** [September 30, 2020, 11:48am UTC](https://discourse.vtk.org/t/access-points-of-a-mesh/4321 "2020-09-30T11:48:27Z")

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Hello everyone, I need to work with 3d points of a loaded mesh. Do you provide any example which shows how to access points of a mesh? Thank you for help!

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## [it is a Qt VTK question ?](https://discourse.vtk.org/t/it-is-a-qt-vtk-question/4189)

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**Author:** [@appollosputnik](https://discourse.vtk.org/u/appollosputnik)\
**Replies:** 1\
**Last updated:** [September 30, 2020, 4:48am UTC](https://discourse.vtk.org/t/it-is-a-qt-vtk-question/4189 "2020-09-30T04:48:27Z")

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Hi folks I need some idea on how we can use QtVTKViews in a QML Window ? I compiled vtk with Qt and found it is generating QtVtkViews but how can we use it in QML Surface ? If anyone knowes I need help…

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## [How to file holes in STL files](https://discourse.vtk.org/t/how-to-file-holes-in-stl-files/4200)

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**Author:** [@gautam\_kumar\_singh](https://discourse.vtk.org/u/gautam_kumar_singh)\
**Replies:** 1\
**Last updated:** [September 30, 2020, 4:43am UTC](https://discourse.vtk.org/t/how-to-file-holes-in-stl-files/4200 "2020-09-30T04:43:59Z")

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Hello, I am wondering how to fill holes appear in STL file. Please suggest

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## [Data caching](https://discourse.vtk.org/t/data-caching/4290)

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**Author:** [@will.schroeder](https://discourse.vtk.org/u/will.schroeder)\
**Replies:** 3\
**Last updated:** [September 28, 2020, 7:44pm UTC](https://discourse.vtk.org/t/data-caching/4290 "2020-09-28T19:44:51Z")

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Lately @utkarshayachit, @cory.quammen, @will.schroeder and others, at the prompting of various customers and driving use cases, have been thinking about caching VTK objects to reduce memory usage and improve performance.…

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## [vtkSplineFilter: Generating mask image.](https://discourse.vtk.org/t/vtksplinefilter-generating-mask-image/4296)

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**Author:** [@Vinod\_Pillai](https://discourse.vtk.org/u/Vinod_Pillai)\
**Replies:** 1\
**Last updated:** [September 25, 2020, 1:58pm UTC](https://discourse.vtk.org/t/vtksplinefilter-generating-mask-image/4296 "2020-09-25T13:58:20Z")

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I have some control points . I am using vtkSplineFilter to uniformly subdivide and generate a closed polyline from these control points. I would like to generate a mask image using the spline filter output, where the re…

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## [Compiling SlicerCAT for MAC OS](https://discourse.vtk.org/t/compiling-slicercat-for-mac-os/4274)

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**Author:** [@flaviu2](https://discourse.vtk.org/u/flaviu2)\
**Replies:** 2\
**Last updated:** [September 23, 2020, 4:41am UTC](https://discourse.vtk.org/t/compiling-slicercat-for-mac-os/4274 "2020-09-23T04:41:22Z")

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I am trying to compile SlicerCAT for IPad. But according to compiling cook book: https://slicer.readthedocs.io/en/latest/developer\_guide/build\_instructions/macos.html#prerequisites I need also QT5, right ? So, this imp…

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## [Why do obj files read more vertices?](https://discourse.vtk.org/t/why-do-obj-files-read-more-vertices/4204)

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**Author:** [@DreamLFairy](https://discourse.vtk.org/u/DreamLFairy)\
**Replies:** 7\
**Last updated:** [September 17, 2020, 7:53pm UTC](https://discourse.vtk.org/t/why-do-obj-files-read-more-vertices/4204 "2020-09-17T19:53:44Z")

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I use it meshlab.exe Open an obj file, or use Notepad to open an obj file. There are only 26408 vertices in it。 The obj file format is as follows (I removed the annotation symbol#): Wavefront OBJ mtllib model.mtl 2…

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## [Fit image exactly into renderWindow](https://discourse.vtk.org/t/fit-image-exactly-into-renderwindow/4232)

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**Author:** [@Seekerp](https://discourse.vtk.org/u/Seekerp)\
**Replies:** 1\
**Last updated:** [September 17, 2020, 2:48pm UTC](https://discourse.vtk.org/t/fit-image-exactly-into-renderwindow/4232 "2020-09-17T14:48:48Z")

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Hi guys. I am following the following VTK example to take a screenshot of my current volume. https://vtk.org/Wiki/VTK/Examples/Cxx/Utilities/Screenshot. However, the screenshot always comes with added whitespace on eith…

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## [surface streamline plot](https://discourse.vtk.org/t/surface-streamline-plot/4230)

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**Author:** [@Mayssa](https://discourse.vtk.org/u/Mayssa)\
**Replies:** 0\
**Last updated:** [September 16, 2020, 4:07pm UTC](https://discourse.vtk.org/t/surface-streamline-plot/4230 "2020-09-16T16:07:06Z")

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Hi all, i want to plot streamline on surface I have tried with this method void CGLModelViewCtrl::CreateSurfaceStreamlinesPlot() { if (m\_pUnstructuredGridModel == NULL) { return; } // convert from unstructuredGrid…

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## [vtkDataObject::ThreadedDeepCopy() ?](https://discourse.vtk.org/t/vtkdataobject-threadeddeepcopy/3537)

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**Author:** [@Dave\_DeMarle](https://discourse.vtk.org/u/Dave_DeMarle)\
**Replies:** 2\
**Last updated:** [September 16, 2020, 12:49pm UTC](https://discourse.vtk.org/t/vtkdataobject-threadeddeepcopy/3537 "2020-09-16T12:49:02Z")

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Greetings, Does there exist such a thing as a threaded version of vtkDataObject::DeepCopy()? It turns out that the DeepCopy that happens inside of vtkTemporalDataSetCache when using extended memory is quite a bottlenec…

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## [Animate, StartViewAnimation and StopViewAnimation: what are they in vtk.js?](https://discourse.vtk.org/t/animate-startviewanimation-and-stopviewanimation-what-are-they-in-vtk-js/4168)

<div class="topic-metadata">

**Author:** [@Ennio\_Bolondi](https://discourse.vtk.org/u/Ennio_Bolondi)\
**Replies:** 5\
**Last updated:** [September 15, 2020, 3:49pm UTC](https://discourse.vtk.org/t/animate-startviewanimation-and-stopviewanimation-what-are-they-in-vtk-js/4168 "2020-09-15T15:49:55Z")

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Hi, I’m try to understand the VTK events system a little bit better. I’m focusing on the animate method, which is enabled by the startViewAnimation method. I’m struggling to understand what is its purpose, because, loo…

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## [Unwanted cutting problem in visualization](https://discourse.vtk.org/t/unwanted-cutting-problem-in-visualization/4171)

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**Author:** [@neuralix](https://discourse.vtk.org/u/neuralix)\
**Replies:** 2\
**Last updated:** [September 9, 2020, 2:43pm UTC](https://discourse.vtk.org/t/unwanted-cutting-problem-in-visualization/4171 "2020-09-09T14:43:07Z")

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Hi, I’m newbie at VTK. When I try to visualize a sphere, and I adjust z value in sphere.SetCenter(0.0, 0.0, z\_value), I only can visualize cut sphere. I guess there is a viewing frame(:cube). How can I extend my viewing…

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## [Optimum window and levels for vtkResliceImageViewer](https://discourse.vtk.org/t/optimum-window-and-levels-for-vtkresliceimageviewer/4157)

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**Author:** [@sherinnovation](https://discourse.vtk.org/u/sherinnovation)\
**Replies:** 1\
**Last updated:** [September 5, 2020, 10:23pm UTC](https://discourse.vtk.org/t/optimum-window-and-levels-for-vtkresliceimageviewer/4157 "2020-09-05T22:23:23Z")

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I am using vtkNIFTIImageReader to read a nifti file(MRI, human head) and for displaying data I am making use of vtkResliceImageViewer. I see that different files have to different would be I am using hardcoded values fo…

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## [vtkDICOMImageReader (000002633B49FDB0):](https://discourse.vtk.org/t/vtkdicomimagereader-000002633b49fdb0/4122)

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**Author:** [@giri\_lakshman](https://discourse.vtk.org/u/giri_lakshman)\
**Replies:** 0\
**Last updated:** [September 2, 2020, 3:47am UTC](https://discourse.vtk.org/t/vtkdicomimagereader-000002633b49fdb0/4122 "2020-09-02T03:47:53Z")

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Hi, I am working on a simple DICOM reader application using Qt framwork. I followed this code: When i try read a DICOM image file, it shows the following error. ERROR: In D:\\VTK\\VTK-9.0.1\\IO\\Image\\vtkDICOMImageRe…

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## [VTK and QDataStream](https://discourse.vtk.org/t/vtk-and-qdatastream/4098)

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**Author:** [@Cesar\_Cherre](https://discourse.vtk.org/u/Cesar_Cherre)\
**Replies:** 1\
**Last updated:** [September 1, 2020, 3:06pm UTC](https://discourse.vtk.org/t/vtk-and-qdatastream/4098 "2020-09-01T15:06:39Z")

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It is possible to put a VTK Poly in a custom struct to save in binary using QDataStream? work with a custom extension .VSprj and need include .obj into my extension

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## [Issue with using vtkPythonUtil::GetObjectFromPointer for custom VTK classes](https://discourse.vtk.org/t/issue-with-using-vtkpythonutil-getobjectfrompointer-for-custom-vtk-classes/4100)

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**Author:** [@jcfr](https://discourse.vtk.org/u/jcfr)\
**Replies:** 10\
**Last updated:** [August 29, 2020, 8:56pm UTC](https://discourse.vtk.org/t/issue-with-using-vtkpythonutil-getobjectfrompointer-for-custom-vtk-classes/4100 "2020-08-29T20:56:05Z")

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Working on updating Slicer to build against the latest VTK (see \[1\]), I noticed that VTK object returned by Qt slots only include vtkObject methods. Question: While I am investigating further, does anyone have ideas on…

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## [Adding Roemer's Boolean Filter as a Remote Module](https://discourse.vtk.org/t/adding-roemers-boolean-filter-as-a-remote-module/1635)

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**Author:** [@lorensen](https://discourse.vtk.org/u/lorensen)\
**Replies:** 37\
**Last updated:** [August 22, 2020, 7:08pm UTC](https://discourse.vtk.org/t/adding-roemers-boolean-filter-as-a-remote-module/1635 "2020-08-22T19:08:54Z")

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@Ron84 I am working on a Merge Request to add Roland Roemer’s Boolean operator filter as a Remote Module. Roemer’s class is supposedly more robust than the existing filters and has several features listed in the README.m…

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## [Regarding 3D image formation with vtkPNGReader](https://discourse.vtk.org/t/regarding-3d-image-formation-with-vtkpngreader/2391)

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**Author:** [@snehal](https://discourse.vtk.org/u/snehal)\
**Replies:** 7\
**Last updated:** [August 21, 2020, 11:59am UTC](https://discourse.vtk.org/t/regarding-3d-image-formation-with-vtkpngreader/2391 "2020-08-21T11:59:39Z")

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I have total 12,000 .png images. Out of those, if I pass 2,000 images on vtkPNGReader() then it is possible to see their 3D images. But when this number increases (\>2,000) then it doesn’t show any kind of expected result…

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## [VTK\_USE\_FILE](https://discourse.vtk.org/t/vtk-use-file/3645)

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**Author:** [@GeorgeS](https://discourse.vtk.org/u/GeorgeS)\
**Replies:** 8\
**Last updated:** [August 21, 2020, 7:23am UTC](https://discourse.vtk.org/t/vtk-use-file/3645 "2020-08-21T07:23:04Z")

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I just upgraded from VTK-8.1.2 to VTK-9.0.0 and am getting a new segmentation fault: \[2A4FCA\]vtkRayCastImageDisplayH:20 WARN| Error: no override found for ‘vtkRayCastImageDisplayHelper’. Segmentation fault: 11 The of…

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## [Trouble between pointer of vtkObject and emscripten](https://discourse.vtk.org/t/trouble-between-pointer-of-vtkobject-and-emscripten/3971)

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**Author:** [@Nicolas\_Lenoir](https://discourse.vtk.org/u/Nicolas_Lenoir)\
**Replies:** 0\
**Last updated:** [August 13, 2020, 1:52pm UTC](https://discourse.vtk.org/t/trouble-between-pointer-of-vtkobject-and-emscripten/3971 "2020-08-13T13:52:07Z")

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Hello I have a question about the using of vtk in the binding of a c++ class that use some vtkObject pointer, in fact I can compile my bind with emscripten and when I run the .js file in output I can execute my test code…

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## [VTK 9 Python vtkContextView not working](https://discourse.vtk.org/t/vtk-9-python-vtkcontextview-not-working/3761)

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**Author:** [@wfenz](https://discourse.vtk.org/u/wfenz)\
**Replies:** 8\
**Last updated:** [August 11, 2020, 12:24pm UTC](https://discourse.vtk.org/t/vtk-9-python-vtkcontextview-not-working/3761 "2020-08-11T12:24:05Z")

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Hello, I tried a simple example showing a 2D Graph in a Context View, which runs without problems in VTK 8.2, but leads to a segmentation fault when using VTK 9.01 (under Windows 10, Python 3.6.8). Is this a known issue,…

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## [Glyph3D normal to polygon](https://discourse.vtk.org/t/glyph3d-normal-to-polygon/3709)

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**Author:** [@efdiloreto](https://discourse.vtk.org/u/efdiloreto)\
**Replies:** 1\
**Last updated:** [August 6, 2020, 1:15pm UTC](https://discourse.vtk.org/t/glyph3d-normal-to-polygon/3709 "2020-08-06T13:15:44Z")

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I’m trying to make a glyph3D normal to a polygon. Maybe I’m misinterpreting the use of normals or my approach is wrong, but I can’t make the glyphs normal to the polygon. This is what I’m getting at the moment. \*\* EDIT\*…

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## [How to integrate VTK with Unity](https://discourse.vtk.org/t/how-to-integrate-vtk-with-unity/1108)

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**Author:** [@Oscar](https://discourse.vtk.org/u/Oscar)\
**Replies:** 8\
**Last updated:** [August 4, 2020, 9:26am UTC](https://discourse.vtk.org/t/how-to-integrate-vtk-with-unity/1108 "2020-08-04T09:26:40Z")

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Hello there, pretty new to the forum and VTK I’m working on a project that need advance rendering in Unity. I’ve thought this would be a achievable through VTK and i still think it can’t be that hard but i’m stuck. The…

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## [How to create a time aware filter that update when its temporal input changed](https://discourse.vtk.org/t/how-to-create-a-time-aware-filter-that-update-when-its-temporal-input-changed/3859)

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**Author:** [@sharon](https://discourse.vtk.org/u/sharon)\
**Replies:** 1\
**Last updated:** [July 29, 2020, 4:23pm UTC](https://discourse.vtk.org/t/how-to-create-a-time-aware-filter-that-update-when-its-temporal-input-changed/3859 "2020-07-29T16:23:19Z")

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Dear All, One of my filter’s input is from a temporal reader, how can make filter aware its input changed and update accordingly? In my case, the reader can read time series files and update correctly, but the filter i…

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## [Point clouds on the surface of the cubes.](https://discourse.vtk.org/t/point-clouds-on-the-surface-of-the-cubes/3837)

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**Author:** [@Mayank\_Srivastava](https://discourse.vtk.org/u/Mayank_Srivastava)\
**Replies:** 0\
**Last updated:** [July 23, 2020, 10:56am UTC](https://discourse.vtk.org/t/point-clouds-on-the-surface-of-the-cubes/3837 "2020-07-23T10:56:51Z")

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Hi, I’m trying to create point clouds of a cube in vtk. I have made a cube which is providing point clouds of the edges using vtkPoints from polydata. I want to create point clouds for the entire cube surface. If possib…

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