# Latest

**URL:** https://discourse.vtk.org/latest.md?page=206

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

**Page:** 207

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## [VtkImage 3d to 2d](https://discourse.vtk.org/t/vtkimage-3d-to-2d/3774)

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**Author:** [@AmBou99](https://discourse.vtk.org/u/AmBou99)\
**Replies:** 5\
**Last updated:** [July 16, 2020, 5:33pm UTC](https://discourse.vtk.org/t/vtkimage-3d-to-2d/3774 "2020-07-16T17:33:14Z")

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Hello everyone, I work on a project and I have a problem. I need to save an image 2d in JPEG or PNG. The problem is : I have a 3d matrix I put the numbers of this matrix in a vtkImage (so this vtkImage is in 3d form…

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## [IEEE SciVis Contest 2020 \*\*\* EXTENDED DEADLINE \*\*\*](https://discourse.vtk.org/t/ieee-scivis-contest-2020-extended-deadline/3792)

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**Author:** [@Thomas\_Theussl](https://discourse.vtk.org/u/Thomas_Theussl)\
**Replies:** 0\
**Last updated:** [July 16, 2020, 4:20pm UTC](https://discourse.vtk.org/t/ieee-scivis-contest-2020-extended-deadline/3792 "2020-07-16T16:20:53Z")

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IEEE SciVis Contest 2020 Submission deadline: August 31, 2020 \*\*\* EXTENDED \*\*\* The SciVis contest is an annual event providing scientific datasets for visualization and data analysis. This year a data set describing com…

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## [Blur skybox](https://discourse.vtk.org/t/blur-skybox/3783)

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**Author:** [@kaiwen](https://discourse.vtk.org/u/kaiwen)\
**Replies:** 3\
**Last updated:** [July 16, 2020, 1:55pm UTC](https://discourse.vtk.org/t/blur-skybox/3783 "2020-07-16T13:55:08Z")

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I want to know how to blur the skybox.

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## [Use vtkHardwareSelector to select point of vtkGlyph3DMapper](https://discourse.vtk.org/t/use-vtkhardwareselector-to-select-point-of-vtkglyph3dmapper/3790)

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**Author:** [@michael23](https://discourse.vtk.org/u/michael23)\
**Replies:** 0\
**Last updated:** [July 16, 2020, 12:17pm UTC](https://discourse.vtk.org/t/use-vtkhardwareselector-to-select-point-of-vtkglyph3dmapper/3790 "2020-07-16T12:17:26Z")

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Hi, I am using vtkGlyph3DMapper for rendering cylinders at certain points. Now I want to click on a cylinder and get the index of the point which was clicked. Here is my code (based on TestGlyph3DMapperCellPicking.cxx…

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## [Best practice for rapidly changing vtkImageData?](https://discourse.vtk.org/t/best-practice-for-rapidly-changing-vtkimagedata/3744)

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**Author:** [@harold.absalom](https://discourse.vtk.org/u/harold.absalom)\
**Replies:** 10\
**Last updated:** [July 16, 2020, 6:02am UTC](https://discourse.vtk.org/t/best-practice-for-rapidly-changing-vtkimagedata/3744 "2020-07-16T06:02:05Z")

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I’m writing an application which takes a 3D vtkImageData\* from an external source, and then displays a number of slices (at least ten) from that data. The external data is updating at a fairly rapid rate (around 30 times…

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## [How to use vtkXdmf3Writer() to write vtkPolyData for multiple time steps?](https://discourse.vtk.org/t/how-to-use-vtkxdmf3writer-to-write-vtkpolydata-for-multiple-time-steps/3785)

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**Author:** [@amit112amit](https://discourse.vtk.org/u/amit112amit)\
**Replies:** 0\
**Last updated:** [July 16, 2020, 4:47am UTC](https://discourse.vtk.org/t/how-to-use-vtkxdmf3writer-to-write-vtkpolydata-for-multiple-time-steps/3785 "2020-07-16T04:47:33Z")

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Hi. I looked at the source code for vtkXdmf3Writer.cxx and it seems to support writing multiple time steps to the output XDMF file. I have a code that generates a polydata object at every time step. I want to write all …

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## [cmake-changes in vtk9.0.1 (occt build error)](https://discourse.vtk.org/t/cmake-changes-in-vtk9-0-1-occt-build-error/3736)

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**Author:** [@looooo](https://discourse.vtk.org/u/looooo)\
**Replies:** 3\
**Last updated:** [July 15, 2020, 4:18pm UTC](https://discourse.vtk.org/t/cmake-changes-in-vtk9-0-1-occt-build-error/3736 "2020-07-15T16:18:24Z")

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Please somebody involved in vtk-development can give a hint what cmake changes were added in vtk9. We are running into: CMake Error at CMakeLists.txt:730 (message): Could not find headers of used third-party products: …

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## [VTK example](https://discourse.vtk.org/t/vtk-example/3769)

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**Author:** [@AmBou99](https://discourse.vtk.org/u/AmBou99)\
**Replies:** 3\
**Last updated:** [July 15, 2020, 12:52pm UTC](https://discourse.vtk.org/t/vtk-example/3769 "2020-07-15T12:52:37Z")

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Hello everyone, I’m new with vtk and in this forum. I have a question about the example on the website of VTK like this example : https://lorensen.github.io/VTKExamples/site/Cxx/IO/JPEGWriter/ I use cmake-gui : for t…

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## [Z-buffer scale](https://discourse.vtk.org/t/z-buffer-scale/3483)

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**Author:** [@j.praptak](https://discourse.vtk.org/u/j.praptak)\
**Replies:** 1\
**Last updated:** [July 14, 2020, 5:28pm UTC](https://discourse.vtk.org/t/z-buffer-scale/3483 "2020-07-14T17:28:45Z")

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Hello. I’m creating a depth map from 3D just like in example: https://vtk.org/Wiki/VTK/Examples/Cxx/Utilities/ZBuffer Is there an easy way to set the output so that the closest point of actor is Whitest (255,255,255) …

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## [How to use NetCDFReader](https://discourse.vtk.org/t/how-to-use-netcdfreader/2397)

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**Author:** [@Alex1](https://discourse.vtk.org/u/Alex1)\
**Replies:** 3\
**Last updated:** [July 14, 2020, 5:23pm UTC](https://discourse.vtk.org/t/how-to-use-netcdfreader/2397 "2020-07-14T17:23:16Z")

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Can someone explain to me how to use the NetCDFReader properly? I already tried this: vtkSmartPointer\<vtkNetCDFReader\> cdfReader = vtkSmartPointer\<vtkNetCDFReader\>::New(); cdfReader-\>SetFileName("example\_nc\_file.nc"); …

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## [VTK Examples Python testing](https://discourse.vtk.org/t/vtk-examples-python-testing/3743)

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**Author:** [@dgobbi](https://discourse.vtk.org/u/dgobbi)\
**Replies:** 4\
**Last updated:** [July 14, 2020, 3:12am UTC](https://discourse.vtk.org/t/vtk-examples-python-testing/3743 "2020-07-14T03:12:53Z")

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I’m putting together some plans for automating the testing the Python examples in the vtk-examples repository. All comments are welcome, especially from @amaclean since you have already done a lot of great work with the…

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## [Is it possible to rubber band select Blocks from a composite data set?](https://discourse.vtk.org/t/is-it-possible-to-rubber-band-select-blocks-from-a-composite-data-set/3765)

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**Author:** [@scotsman60](https://discourse.vtk.org/u/scotsman60)\
**Replies:** 0\
**Last updated:** [July 13, 2020, 8:41pm UTC](https://discourse.vtk.org/t/is-it-possible-to-rubber-band-select-blocks-from-a-composite-data-set/3765 "2020-07-13T20:41:16Z")

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Hello, I’m working with multiblock datasets and trying to figure out how best to select (and subsequently highlight) the contents of blocks that are selected using rubber band picking. It seems that vtkSelection/vtkSel…

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## [Draw outline of 3D object](https://discourse.vtk.org/t/draw-outline-of-3d-object/3711)

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**Author:** [@rprueckl](https://discourse.vtk.org/u/rprueckl)\
**Replies:** 4\
**Last updated:** [July 13, 2020, 7:05am UTC](https://discourse.vtk.org/t/draw-outline-of-3d-object/3711 "2020-07-13T07:05:19Z")

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Hi, is there a possibility to render the outline of a 3D object just like Blender does? I mean the orange outline that is displayed around the maximum extents of the object when selected: Thanks for your help.

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## [A July 2020 VTK Hackathon](https://discourse.vtk.org/t/a-july-2020-vtk-hackathon/3600)

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**Author:** [@will.schroeder](https://discourse.vtk.org/u/will.schroeder)\
**Replies:** 37\
**Last updated:** [July 13, 2020, 6:56am UTC](https://discourse.vtk.org/t/a-july-2020-vtk-hackathon/3600 "2020-07-13T06:56:40Z")

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It’s time for another VTK hackathon. Given relatively recent events, and after talking to several folks (thanks Andrew, Seb, Rob, Ben, and others), I’d like to hold the hackathon in memory of Bill Lorensen (who died in D…

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## [How to write cell data changed over time into one file by \`vtk.vtkXMLUnstructuredGridWriter\`?](https://discourse.vtk.org/t/how-to-write-cell-data-changed-over-time-into-one-file-by-vtk-vtkxmlunstructuredgridwriter/3759)

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**Author:** [@whymath](https://discourse.vtk.org/u/whymath)\
**Replies:** 0\
**Last updated:** [July 13, 2020, 5:08am UTC](https://discourse.vtk.org/t/how-to-write-cell-data-changed-over-time-into-one-file-by-vtk-vtkxmlunstructuredgridwriter/3759 "2020-07-13T05:08:38Z")

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I have a triangle mesh, and want to write some cell data which changed over time into a test.vtu files by vtk python interface. import numpy as np import vtk import vtk.util.numpy\_support as vnp mesh =vtk.vtkUnstructur…

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## [Color/hide blocks on a vtkMultiBlockDataSet using vtkCompositePolyDataMapper2 and the block FieldData?](https://discourse.vtk.org/t/color-hide-blocks-on-a-vtkmultiblockdataset-using-vtkcompositepolydatamapper2-and-the-block-fielddata/3755)

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**Author:** [@scotsman60](https://discourse.vtk.org/u/scotsman60)\
**Replies:** 0\
**Last updated:** [July 13, 2020, 2:06am UTC](https://discourse.vtk.org/t/color-hide-blocks-on-a-vtkmultiblockdataset-using-vtkcompositepolydatamapper2-and-the-block-fielddata/3755 "2020-07-13T02:06:40Z")

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I’m working with vtkMultiBlockDataSets and using vtkCompositePolyDataMapper2 using Python 3 and VTK 9 on Windows 10 My model has the color of each block associated with the PolyData as FieldData - a 3 component Scalar a…

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## [Crash in vtkPolyData.GetCell](https://discourse.vtk.org/t/crash-in-vtkpolydata-getcell/3731)

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**Author:** [@efahl](https://discourse.vtk.org/u/efahl)\
**Replies:** 8\
**Last updated:** [July 12, 2020, 7:00pm UTC](https://discourse.vtk.org/t/crash-in-vtkpolydata-getcell/3731 "2020-07-12T19:00:03Z")

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I’m getting a seg fault when trying to extract a cut boundary…I think. I’m using Visual Studio and Python 3.8, which don’t work together yet, so I can see the cxx code at the point of failure, but have no idea how I got…

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## [Get the normal vector of a polygon using vtkPolyDataNormals](https://discourse.vtk.org/t/get-the-normal-vector-of-a-polygon-using-vtkpolydatanormals/3751)

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**Author:** [@efdiloreto](https://discourse.vtk.org/u/efdiloreto)\
**Replies:** 4\
**Last updated:** [July 11, 2020, 11:48pm UTC](https://discourse.vtk.org/t/get-the-normal-vector-of-a-polygon-using-vtkpolydatanormals/3751 "2020-07-11T23:48:31Z")

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I have a simple polygon where all points belong to the same plane, therefore the normal vectors at each point should be the same. The problem I have is that I can’t get those vectors. For example, I have the following c…

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## [Getting a scalar value by checking vtkColorTransferFunction RGB color](https://discourse.vtk.org/t/getting-a-scalar-value-by-checking-vtkcolortransferfunction-rgb-color/3571)

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**Author:** [@lonewolf](https://discourse.vtk.org/u/lonewolf)\
**Replies:** 4\
**Last updated:** [July 11, 2020, 11:35pm UTC](https://discourse.vtk.org/t/getting-a-scalar-value-by-checking-vtkcolortransferfunction-rgb-color/3571 "2020-07-11T23:35:23Z")

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Hi all, I have been using VTK for some years now but a new challenge popped up. I need to reverse engineer the function void vtkColorTransferFunction::GetTable( double xStart, double xEnd, int size, double\* table ) i…

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## [Can VTK be integrated with an existing CPQ(configure, price, quote) software to make automated drawings in the background based on parametric values provided?](https://discourse.vtk.org/t/can-vtk-be-integrated-with-an-existing-cpq-configure-price-quote-software-to-make-automated-drawings-in-the-background-based-on-parametric-values-provided/3745)

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**Author:** [@Dishant\_Bhatt](https://discourse.vtk.org/u/Dishant_Bhatt)\
**Replies:** 5\
**Last updated:** [July 10, 2020, 8:37am UTC](https://discourse.vtk.org/t/can-vtk-be-integrated-with-an-existing-cpq-configure-price-quote-software-to-make-automated-drawings-in-the-background-based-on-parametric-values-provided/3745 "2020-07-10T08:37:45Z")

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Let’s say a user wants to build and buy a house from scratch. He logs in to a CPQ (configure price quote ) software and starts putting in various details like length, breadth, height, volume, number of widows, the type o…

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## [Sudden linking error on macOS on same version that used to build (8.2.0)](https://discourse.vtk.org/t/sudden-linking-error-on-macos-on-same-version-that-used-to-build-8-2-0/3742)

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**Author:** [@rdbisme](https://discourse.vtk.org/u/rdbisme)\
**Replies:** 1\
**Last updated:** [July 10, 2020, 1:58am UTC](https://discourse.vtk.org/t/sudden-linking-error-on-macos-on-same-version-that-used-to-build-8-2-0/3742 "2020-07-10T01:58:59Z")

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I’m trying to fix the Macports package of vtk that ships 8.2.0 version and that needs the fix for tp\_print with python 3.8. The problem is that this version used to build successfully without Python (I did not change th…

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## [Extracting directionality from NIfTI files](https://discourse.vtk.org/t/extracting-directionality-from-nifti-files/3719)

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**Author:** [@msmerps](https://discourse.vtk.org/u/msmerps)\
**Replies:** 5\
**Last updated:** [July 9, 2020, 9:08pm UTC](https://discourse.vtk.org/t/extracting-directionality-from-nifti-files/3719 "2020-07-09T21:08:40Z")

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Hi everyone, I have written a simple VTK NIfTI file viewer and want to be able to indicate which side of the images is left. By default, vtkNIFTIImageReader provides the data in voxel space, which has arbitrary orientat…

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## [Trying to load custom loaded images into vtkImageImport](https://discourse.vtk.org/t/trying-to-load-custom-loaded-images-into-vtkimageimport/3704)

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**Author:** [@Bandark](https://discourse.vtk.org/u/Bandark)\
**Replies:** 15\
**Last updated:** [July 9, 2020, 1:20pm UTC](https://discourse.vtk.org/t/trying-to-load-custom-loaded-images-into-vtkimageimport/3704 "2020-07-09T13:20:28Z")

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Hello everyone, I’m trying to load custom loaded images (because at my workplace i must use this library) to vtkImageImport (and at the end to vtkImageData, to render a Volume). I have this object dicomStack that alrea…

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## [vtkImplicitSelectionLoop does not work as expected](https://discourse.vtk.org/t/vtkimplicitselectionloop-does-not-work-as-expected/3342)

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**Author:** [@jaswantp](https://discourse.vtk.org/u/jaswantp)\
**Replies:** 0\
**Last updated:** [May 19, 2020, 5:06pm UTC](https://discourse.vtk.org/t/vtkimplicitselectionloop-does-not-work-as-expected/3342 "2020-05-19T17:06:49Z")

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I implemented a function that clips a polydata from another polydata. The clip operation is fine for polys that don’t have sharp corners, but it gives weird results for those with sharp corners. How do I get about this? …

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## [It is posible to modify a glyph after the actor creation?](https://discourse.vtk.org/t/it-is-posible-to-modify-a-glyph-after-the-actor-creation/3727)

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**Author:** [@efdiloreto](https://discourse.vtk.org/u/efdiloreto)\
**Replies:** 2\
**Last updated:** [July 8, 2020, 6:22pm UTC](https://discourse.vtk.org/t/it-is-posible-to-modify-a-glyph-after-the-actor-creation/3727 "2020-07-08T18:22:39Z")

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For example, I created an arrow and I want to modify the scale and the orientation. For the orientation I can use (before the actor creation) the vtkArrowSource “InvertOn” method, and for the scale the vtkGlyph3D “SetSc…

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## [Scaling a rendering scene](https://discourse.vtk.org/t/scaling-a-rendering-scene/173)

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**Author:** [@banesullivan](https://discourse.vtk.org/u/banesullivan)\
**Replies:** 13\
**Last updated:** [July 8, 2020, 1:26pm UTC](https://discourse.vtk.org/t/scaling-a-rendering-scene/173 "2020-07-08T13:26:53Z")

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Overview: I’m curious about scaling a rendering scene for a feature in an open-source, VTK-based project I have been contributing to: vtki. Overall, vtki provides an intuitive, pythonic means of interfacing with VTK dat…

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## [What's wrong with my VTU file?](https://discourse.vtk.org/t/whats-wrong-with-my-vtu-file/3721)

<div class="topic-metadata">

**Author:** [@jrwrigh](https://discourse.vtk.org/u/jrwrigh)\
**Replies:** 3\
**Last updated:** [July 7, 2020, 8:12pm UTC](https://discourse.vtk.org/t/whats-wrong-with-my-vtu-file/3721 "2020-07-07T20:12:05Z")

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When I try to open the following VTK file in Paraview, it says that a reader could not be found. In looking at other forum posts, this probably means that the file format is invalid. However, due to the scarcity of examp…

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## [Generating a mesh from vtkPolyData in C++](https://discourse.vtk.org/t/generating-a-mesh-from-vtkpolydata-in-c/3713)

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**Author:** [@beginner](https://discourse.vtk.org/u/beginner)\
**Replies:** 1\
**Last updated:** [July 7, 2020, 2:51pm UTC](https://discourse.vtk.org/t/generating-a-mesh-from-vtkpolydata-in-c/3713 "2020-07-07T14:51:13Z")

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Hello, I’ve tried using vtkGreedyTerrainDecimation but it doesn’t seem to work in alignment with what I am doing. Also, I am trying to use reconstruction methods that don’t require a remote library. Are there any sugges…

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## [pick 3D Widgets in openGL window](https://discourse.vtk.org/t/pick-3d-widgets-in-opengl-window/3717)

<div class="topic-metadata">

**Author:** [@kimia.af1998](https://discourse.vtk.org/u/kimia.af1998)\
**Replies:** 0\
**Last updated:** [July 7, 2020, 1:54pm UTC](https://discourse.vtk.org/t/pick-3d-widgets-in-opengl-window/3717 "2020-07-07T13:54:48Z")

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Hi I have a 2D distance widget and 3D distance widget. I want to pick them by left button click. I’ve done well the distance widget on 2D image but I cannot pick the 3D one(vtkDistanceRepresentation3D) in opengl window. …

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## [VTKm: ThrowCastAndCallException when calling paint() on a View3D](https://discourse.vtk.org/t/vtkm-throwcastandcallexception-when-calling-paint-on-a-view3d/3712)

<div class="topic-metadata">

**Author:** [@McDave17](https://discourse.vtk.org/u/McDave17)\
**Replies:** 1\
**Last updated:** [July 7, 2020, 9:52am UTC](https://discourse.vtk.org/t/vtkm-throwcastandcallexception-when-calling-paint-on-a-view3d/3712 "2020-07-07T09:52:54Z")

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Since the last topic I posted this in got quite of topic from the original topic I want to post this here again. As stated in the title this code unexpectedly crashes when calling paint() on the initiated View3D. This s…

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