# Latest

**URL:** https://discourse.vtk.org/latest.md?page=182

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

**Page:** 183

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## [vtkFrustumSelector and poly-lines](https://discourse.vtk.org/t/vtkfrustumselector-and-poly-lines/5258)

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**Author:** [@Aron\_Helser](https://discourse.vtk.org/u/Aron_Helser)\
**Replies:** 2\
**Last updated:** [March 13, 2021, 9:37pm UTC](https://discourse.vtk.org/t/vtkfrustumselector-and-poly-lines/5258 "2021-03-13T21:37:30Z")

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I’ve identified an unexpected behavior in frustum-selection, and wanted to ask whether others think it’s a bug or a feature. We’re using a small 9x9 pixel frustum around the mouse click to select all poly-lines near the…

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## [Problems encountered in multi-GPU rendering](https://discourse.vtk.org/t/problems-encountered-in-multi-gpu-rendering/5366)

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**Author:** [@Jone7](https://discourse.vtk.org/u/Jone7)\
**Replies:** 1\
**Last updated:** [March 12, 2021, 3:51pm UTC](https://discourse.vtk.org/t/problems-encountered-in-multi-gpu-rendering/5366 "2021-03-12T15:51:37Z")

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I tried to render a large scale model with VTK on two GPUs, but found that one of the GPUs was underutilized, like this: Does the VTK not support multiple GPUs? Or has it unique Settings?

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## [Store complex value in PointData](https://discourse.vtk.org/t/store-complex-value-in-pointdata/5355)

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**Author:** [@cean\_wang](https://discourse.vtk.org/u/cean_wang)\
**Replies:** 1\
**Last updated:** [March 11, 2021, 5:18pm UTC](https://discourse.vtk.org/t/store-complex-value-in-pointdata/5355 "2021-03-11T17:18:39Z")

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Hi, I want to store Complex Displacement Vector in PointData. For each point, there is Magnitude and Phase value of displacement(T) in X(T1),Y(T2) and Z(T3) axis. What is the format? Is it: T1Mag,T1Phase,T2Mag,T2Phase,…

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## [New feature: vtkDataSet::GetPointsDataArray ?](https://discourse.vtk.org/t/new-feature-vtkdataset-getpointsdataarray/5351)

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**Author:** [@Yohann\_Bearzi](https://discourse.vtk.org/u/Yohann_Bearzi)\
**Replies:** 12\
**Last updated:** [March 11, 2021, 3:18pm UTC](https://discourse.vtk.org/t/new-feature-vtkdataset-getpointsdataarray/5351 "2021-03-11T15:18:02Z")

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It already has occurred to me a few times that, while developing a filter for VTK, I would need to iterate on points in a generic vtkDataSet. This can currently be done by calling void vtkDataSet::GetPoint(vtkIdType, dou…

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## [vtkPolyDataAppend of circles make holes in intersections](https://discourse.vtk.org/t/vtkpolydataappend-of-circles-make-holes-in-intersections/5367)

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**Author:** [@zandarina](https://discourse.vtk.org/u/zandarina)\
**Replies:** 0\
**Last updated:** [March 11, 2021, 12:51pm UTC](https://discourse.vtk.org/t/vtkpolydataappend-of-circles-make-holes-in-intersections/5367 "2021-03-11T12:51:09Z")

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Hello, I want to delete some areas of a polydata transformed to image. It works well but it is very slow. For every circle, I make an extrusion towards the normal and I convert it into image, and substract it to the …

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## [Rotating vectors around an axis](https://discourse.vtk.org/t/rotating-vectors-around-an-axis/5365)

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**Author:** [@Guillaume\_Gillet](https://discourse.vtk.org/u/Guillaume_Gillet)\
**Replies:** 2\
**Last updated:** [March 11, 2021, 8:58am UTC](https://discourse.vtk.org/t/rotating-vectors-around-an-axis/5365 "2021-03-11T08:58:43Z")

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So, i have a vector field i need to display in vtk, i have x and y coordinates (it’s a vector field on a 0 z axis, just a plane) but i also have for every vector a rotation around an axis, so what i’m asking here is, is …

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## [VTK 9.0.1 Data and LargeData](https://discourse.vtk.org/t/vtk-9-0-1-data-and-largedata/5361)

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**Author:** [@robodoc](https://discourse.vtk.org/u/robodoc)\
**Replies:** 1\
**Last updated:** [March 10, 2021, 6:56pm UTC](https://discourse.vtk.org/t/vtk-9-0-1-data-and-largedata/5361 "2021-03-10T18:56:51Z")

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In updating to 9.0.1 it seems that the Data and Large Data files do not correctly untar/unzip when I attempt to extract them using 7-Zip. In the data folder I get nothing, and what I do get are hashes or uids, which are…

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## [PDBReader issue](https://discourse.vtk.org/t/pdbreader-issue/5331)

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**Author:** [@mauro](https://discourse.vtk.org/u/mauro)\
**Replies:** 1\
**Last updated:** [March 10, 2021, 5:04pm UTC](https://discourse.vtk.org/t/pdbreader-issue/5331 "2021-03-10T17:04:37Z")

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Hi all, here a newbie question. I’m having troubles with the PDBReader when importing: import vtkPDBReader from ‘vtk.js/Sources/IO/Misc/PDBReader’; the error is also with PDBReader example: node\_modules/vtk.js/Source…

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## [vtk handling of python file-like objects, gzipped stls](https://discourse.vtk.org/t/vtk-handling-of-python-file-like-objects-gzipped-stls/5350)

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**Author:** [@aerogt3](https://discourse.vtk.org/u/aerogt3)\
**Replies:** 2\
**Last updated:** [March 9, 2021, 4:46pm UTC](https://discourse.vtk.org/t/vtk-handling-of-python-file-like-objects-gzipped-stls/5350 "2021-03-09T16:46:45Z")

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Hello, I am using python vtk for reading in, manipulating, and then exporting .stl files. Often these are gzipped, or download from/exported to a remote file system (amazon s3). If there any way to use vtkSTLReader and…

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## [Advice on grid formats](https://discourse.vtk.org/t/advice-on-grid-formats/5343)

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**Author:** [@Luke\_Dalessandro](https://discourse.vtk.org/u/Luke_Dalessandro)\
**Replies:** 6\
**Last updated:** [March 9, 2021, 3:07pm UTC](https://discourse.vtk.org/t/advice-on-grid-formats/5343 "2021-03-09T15:07:47Z")

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Hi all. For the last couple of years I have been using the vtkUnstructuredGrid file format as an output format for my solver infrastructure–-basically it’s storing N-dimensional \[point\]→(f0,f1,...) scalar data correspon…

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## [RegularPolygonSource shows edges](https://discourse.vtk.org/t/regularpolygonsource-shows-edges/5346)

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**Author:** [@zandarina](https://discourse.vtk.org/u/zandarina)\
**Replies:** 0\
**Last updated:** [March 9, 2021, 10:01am UTC](https://discourse.vtk.org/t/regularpolygonsource-shows-edges/5346 "2021-03-09T10:01:51Z")

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Hello I have a question, I am trying to use RegularPolygonSource to paint in a 3d scene and the edge is shown. I have tried to change the properties of the actor to visibilit edges off o line width to 0 but there is no w…

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## [Error for read bmp file](https://discourse.vtk.org/t/error-for-read-bmp-file/5345)

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**Author:** [@xiaocaiji](https://discourse.vtk.org/u/xiaocaiji)\
**Replies:** 0\
**Last updated:** [March 9, 2021, 6:52am UTC](https://discourse.vtk.org/t/error-for-read-bmp-file/5345 "2021-03-09T06:52:44Z")

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Thanks for attention. I succeed building the example ReadBmp and running it in cmd. Then I try to run the code in visual studio. But once I modify the code: reader-\>SetFileName(argv\[1\]); to reader-\>SetFileName(“m…

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## [Manipulate a image of VTK in CUDA](https://discourse.vtk.org/t/manipulate-a-image-of-vtk-in-cuda/5339)

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**Author:** [@Luis\_Carlos\_Carneiro](https://discourse.vtk.org/u/Luis_Carlos_Carneiro)\
**Replies:** 4\
**Last updated:** [March 8, 2021, 9:05pm UTC](https://discourse.vtk.org/t/manipulate-a-image-of-vtk-in-cuda/5339 "2021-03-08T21:05:38Z")

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Dear All, I want to manipulate a VTK image in CUDA (PyCUDA): reader1 = vtk.vtkMetaImageReader() reader1.SetFileName('c:\\\\users\\\\luisgo//catia\_pre//'+'binary2.mhd') reader1.Update() reade…

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## [How to handle cmake COMPONENTS name change between 8.2 and 9.](https://discourse.vtk.org/t/how-to-handle-cmake-components-name-change-between-8-2-and-9/5338)

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**Author:** [@Luke\_Dalessandro](https://discourse.vtk.org/u/Luke_Dalessandro)\
**Replies:** 11\
**Last updated:** [March 8, 2021, 4:57pm UTC](https://discourse.vtk.org/t/how-to-handle-cmake-components-name-change-between-8-2-and-9/5338 "2021-03-08T16:57:57Z")

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I’ve been using vtk8.2 successfully for a while now, with a basic find\_package(VTK REQUIRED COMPONENTS vtkCommonCore vtkCommonDataModel vtkIOXML) however, vtk9 changed those component names. How do I know which c…

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## [Labeled Contours](https://discourse.vtk.org/t/labeled-contours/5342)

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**Author:** [@jwhite](https://discourse.vtk.org/u/jwhite)\
**Replies:** 0\
**Last updated:** [March 8, 2021, 3:58pm UTC](https://discourse.vtk.org/t/labeled-contours/5342 "2021-03-08T15:58:45Z")

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Hello, I’m writing a program in C# that shows the stress and strain from aircraft on a slab of concrete and would like to label the contours I generate based on those values. I have the contours being drawn correctly b…

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## [Adaptive render facets in VTK?](https://discourse.vtk.org/t/adaptive-render-facets-in-vtk/5333)

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**Author:** [@GregVernon](https://discourse.vtk.org/u/GregVernon)\
**Replies:** 1\
**Last updated:** [March 7, 2021, 12:38pm UTC](https://discourse.vtk.org/t/adaptive-render-facets-in-vtk/5333 "2021-03-07T12:38:18Z")

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Is there any functionality in VTK for adaptive render facets (of nonlinear curves and surfaces) based on the current view? I know there’s the LOD functionality in ParaView, but that reduces the fidelity during view tran…

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## [how to read .vti files created from stack of 2d PNG Images and render it in vtk.js](https://discourse.vtk.org/t/how-to-read-vti-files-created-from-stack-of-2d-png-images-and-render-it-in-vtk-js/5287)

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**Author:** [@Saptarshi\_Paul](https://discourse.vtk.org/u/Saptarshi_Paul)\
**Replies:** 22\
**Last updated:** [March 6, 2021, 5:42pm UTC](https://discourse.vtk.org/t/how-to-read-vti-files-created-from-stack-of-2d-png-images-and-render-it-in-vtk-js/5287 "2021-03-06T17:42:22Z")

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Hello Everyone, I was able to create a test2.vti file using stack of 2d png images which i want to volume render in vtk.js. I used xmlImageDataReader.parseAsArrayBuffer(‘test2.vti’), but it threw me an error, Failed to …

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## [Enable parallel projection without resetting the camera](https://discourse.vtk.org/t/enable-parallel-projection-without-resetting-the-camera/5289)

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**Author:** [@rodrigomologni](https://discourse.vtk.org/u/rodrigomologni)\
**Replies:** 9\
**Last updated:** [March 6, 2021, 4:51pm UTC](https://discourse.vtk.org/t/enable-parallel-projection-without-resetting-the-camera/5289 "2021-03-06T16:51:20Z")

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Hi, Support! When I press P to enable parallel projection, the camera is “restarted”. Is this a bug? Must I reimplement the transformations to overcome this problem or is there a simpler solution? Thanks for any help! …

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## [How to set representation from points to surface?](https://discourse.vtk.org/t/how-to-set-representation-from-points-to-surface/5335)

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**Author:** [@vandoitruong1997](https://discourse.vtk.org/u/vandoitruong1997)\
**Replies:** 0\
**Last updated:** [March 6, 2021, 1:42pm UTC](https://discourse.vtk.org/t/how-to-set-representation-from-points-to-surface/5335 "2021-03-06T13:42:07Z")

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Hello everyone, I am a newbie in vtk, I want to create the application with winform to visualize a science data. Specifically, My data is a “.vtk” file format, with uniform structured and scalars data. I already try thi…

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## [Feed the output of a Filter to the same Filter's Input in a Loop](https://discourse.vtk.org/t/feed-the-output-of-a-filter-to-the-same-filters-input-in-a-loop/5310)

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**Author:** [@mallikarjun49](https://discourse.vtk.org/u/mallikarjun49)\
**Replies:** 4\
**Last updated:** [March 5, 2021, 5:46pm UTC](https://discourse.vtk.org/t/feed-the-output-of-a-filter-to-the-same-filters-input-in-a-loop/5310 "2021-03-05T17:46:03Z")

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Hello All, I would like to do boolean operation repeatedly on the output of the boolean filter itself like below. auto boolFilter = vtkSmartPointer\<vtkPolyDataBooleanFilter\>::New(); boolFilter-\>SetOperModeToDifference…

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## [Can the VTK get the world coordinates of the vertices in the read model in the OpenGL shader?](https://discourse.vtk.org/t/can-the-vtk-get-the-world-coordinates-of-the-vertices-in-the-read-model-in-the-opengl-shader/5325)

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**Author:** [@Jone7](https://discourse.vtk.org/u/Jone7)\
**Replies:** 1\
**Last updated:** [March 5, 2021, 4:01pm UTC](https://discourse.vtk.org/t/can-the-vtk-get-the-world-coordinates-of-the-vertices-in-the-read-model-in-the-opengl-shader/5325 "2021-03-05T16:01:21Z")

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I want to use the world coordinates of the model to do the lighting calculation, and I saw in VTK opengl shader can get the model coordinates and view coordinates of vertex, I think that using model matrix multiplicate…

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## [Migration from VTK 5.10 to VTK 6.3](https://discourse.vtk.org/t/migration-from-vtk-5-10-to-vtk-6-3/5329)

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**Author:** [@PotatoGirl](https://discourse.vtk.org/u/PotatoGirl)\
**Replies:** 1\
**Last updated:** [March 5, 2021, 3:18pm UTC](https://discourse.vtk.org/t/migration-from-vtk-5-10-to-vtk-6-3/5329 "2021-03-05T15:18:19Z")

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Hello everyone, I had to perform a migration from VTK 5.10 to VTK 6.3 recently, but I have been stuck with an unexpected behavior with the vtkImageData I’m trying to visualize. The values that should be fully transparen…

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## [VTK raycasting aliasing lines](https://discourse.vtk.org/t/vtk-raycasting-aliasing-lines/5321)

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**Author:** [@desheng](https://discourse.vtk.org/u/desheng)\
**Replies:** 2\
**Last updated:** [March 5, 2021, 2:35pm UTC](https://discourse.vtk.org/t/vtk-raycasting-aliasing-lines/5321 "2021-03-05T14:35:42Z")

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Tried to generate raycasting for a knee CT, but the resulting image shows some aliasing lines, as shown in the image. Anyone can help me out? Thanks!

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## [Using VTK gradient filter to calculate the divergence of a vector field](https://discourse.vtk.org/t/using-vtk-gradient-filter-to-calculate-the-divergence-of-a-vector-field/5319)

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**Author:** [@Renard](https://discourse.vtk.org/u/Renard)\
**Replies:** 2\
**Last updated:** [March 5, 2021, 9:19am UTC](https://discourse.vtk.org/t/using-vtk-gradient-filter-to-calculate-the-divergence-of-a-vector-field/5319 "2021-03-05T09:19:08Z")

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Hi, I have written a simple code in python to calculate the divergence of a vector field stored in a VTU file. I’m getting the following error, what is going wrong here? TypeError: method requires a string argument imp…

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## [Cylinder Demo bugs in ver 8.2.0 on Fedora 32 with NVidia hardware](https://discourse.vtk.org/t/cylinder-demo-bugs-in-ver-8-2-0-on-fedora-32-with-nvidia-hardware/4310)

<div class="topic-metadata">

**Author:** [@DavidChipman](https://discourse.vtk.org/u/DavidChipman)\
**Replies:** 11\
**Last updated:** [March 5, 2021, 6:23am UTC](https://discourse.vtk.org/t/cylinder-demo-bugs-in-ver-8-2-0-on-fedora-32-with-nvidia-hardware/4310 "2021-03-05T06:23:18Z")

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I have a problem getting the Cylinder demo program to work properly on Fedora 32, with NVidia drviers. However, to do something similar in ParaView 5.8 works just fine.

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## [Share interactors](https://discourse.vtk.org/t/share-interactors/5324)

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**Author:** [@Jothybasu\_Selvaraj](https://discourse.vtk.org/u/Jothybasu_Selvaraj)\
**Replies:** 1\
**Last updated:** [March 5, 2021, 2:42am UTC](https://discourse.vtk.org/t/share-interactors/5324 "2021-03-05T02:42:44Z")

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Hi all, I am trying to share the same interactor among three renderers. here is the code i tried but it will only apply in to the last renderer. Any hints how to do this properly? vtkSmartPointeriact= vtkSmartPointer:…

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## [Display subset of polydata](https://discourse.vtk.org/t/display-subset-of-polydata/5267)

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**Author:** [@nelly](https://discourse.vtk.org/u/nelly)\
**Replies:** 7\
**Last updated:** [March 5, 2021, 1:19am UTC](https://discourse.vtk.org/t/display-subset-of-polydata/5267 "2021-03-05T01:19:45Z")

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Hi, I have a structured grid whose cells have a property ‘Pressure’ which I have converted to polydata and am building an app for interacting with. One goal is for the user of my app to be able to interact with a slider…

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## [VTK grid: define cells with (i,j,k) index](https://discourse.vtk.org/t/vtk-grid-define-cells-with-i-j-k-index/5323)

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**Author:** [@Mohamedelhamzawy](https://discourse.vtk.org/u/Mohamedelhamzawy)\
**Replies:** 1\
**Last updated:** [March 4, 2021, 11:34pm UTC](https://discourse.vtk.org/t/vtk-grid-define-cells-with-i-j-k-index/5323 "2021-03-04T23:34:45Z")

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Hello everyone, I am pretty new to vtk. I am using openvdb for a slam application and I am trying to use VTK for visualization. So lets say I have a 3d grid with size of 100x100x100. And lets say, I want to visualize s…

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## [How to extract boundary cells from a vtkUnstructuredGrid of solid cells](https://discourse.vtk.org/t/how-to-extract-boundary-cells-from-a-vtkunstructuredgrid-of-solid-cells/5312)

<div class="topic-metadata">

**Author:** [@scotsman60](https://discourse.vtk.org/u/scotsman60)\
**Replies:** 1\
**Last updated:** [March 4, 2021, 3:54pm UTC](https://discourse.vtk.org/t/how-to-extract-boundary-cells-from-a-vtkunstructuredgrid-of-solid-cells/5312 "2021-03-04T15:54:31Z")

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Hello!!! I am trying to extract all cells that touch the free surface of a solid mesh in a vtkUnstrucuredGrid - basically to ge the first layer of cells on the bondary. I figured I’d get all of the points on the free s…

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## [Object size](https://discourse.vtk.org/t/object-size/5308)

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**Author:** [@mauro](https://discourse.vtk.org/u/mauro)\
**Replies:** 1\
**Last updated:** [March 4, 2021, 9:51am UTC](https://discourse.vtk.org/t/object-size/5308 "2021-03-04T09:51:48Z")

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Dear all, I’m reading a volume from a file (.vtk) using vtkGenericDataObjectReader, in python: reader = vtk.vtkGenericDataObjectReader() reader.SetFileName( "file.vtk" ) It reads the file with no issues. However, I’m …

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