# Latest

**URL:** https://discourse.vtk.org/latest.md?page=199

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

**Page:** 200

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## [Switching to show different dataarrays (edited)](https://discourse.vtk.org/t/switching-to-show-different-dataarrays-edited/4231)

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**Author:** [@samm-vs](https://discourse.vtk.org/u/samm-vs)\
**Replies:** 4\
**Last updated:** [September 22, 2020, 5:51pm UTC](https://discourse.vtk.org/t/switching-to-show-different-dataarrays-edited/4231 "2020-09-22T17:51:01Z")

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As the past few questions show, I am still really new to this and would appreciate any help available. My question is can you color a vti file using cell data? if so, is there a way to tell the volumeMapper or Volume act…

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## [Adding Light to the volume I am rendering](https://discourse.vtk.org/t/adding-light-to-the-volume-i-am-rendering/4270)

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**Author:** [@samm-vs](https://discourse.vtk.org/u/samm-vs)\
**Replies:** 5\
**Last updated:** [September 22, 2020, 5:48pm UTC](https://discourse.vtk.org/t/adding-light-to-the-volume-i-am-rendering/4270 "2020-09-22T17:48:42Z")

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I was able to get my volume rendered and it looks very nice but I would like to add a light from like an angle so the shadows will give the user a better view of the volume. I saw that I can use vtkLight, is there any ex…

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## [VTKPython for 9.0](https://discourse.vtk.org/t/vtkpython-for-9-0/4260)

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**Author:** [@Francesc](https://discourse.vtk.org/u/Francesc)\
**Replies:** 4\
**Last updated:** [September 22, 2020, 9:08am UTC](https://discourse.vtk.org/t/vtkpython-for-9-0/4260 "2020-09-22T09:08:10Z")

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Hello, I am a new VTK user. So far I have downloaded VTK9.0 and build it with no issues. Now I am looking for VTKPython for Windows. How should I get it for 9.0? The python wheels have not worked for me. What is the m…

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## [The vtk VoxelContoursToSurfaceFilter output is not closed surface](https://discourse.vtk.org/t/the-vtk-voxelcontourstosurfacefilter-output-is-not-closed-surface/4258)

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**Author:** [@guojunjie4SD](https://discourse.vtk.org/u/guojunjie4SD)\
**Replies:** 7\
**Last updated:** [September 21, 2020, 7:12pm UTC](https://discourse.vtk.org/t/the-vtk-voxelcontourstosurfacefilter-output-is-not-closed-surface/4258 "2020-09-21T19:12:34Z")

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I used closed polygons as input polydata， but the result is not closed。 Anyone can give me some advice？ How to make the output closed? Mesh reconstruction(const Ring3dList &ring\_list, double slice\_spacing) { // ring3…

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## [VTK for begineer user.](https://discourse.vtk.org/t/vtk-for-begineer-user/4264)

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**Author:** [@semmana26](https://discourse.vtk.org/u/semmana26)\
**Replies:** 9\
**Last updated:** [September 21, 2020, 6:43pm UTC](https://discourse.vtk.org/t/vtk-for-begineer-user/4264 "2020-09-21T18:43:13Z")

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Hello everyone, I am a new user. I am asking the way to install VTK and tutorials and courses related with structural mechanic using VTK?

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## [How to catch window close events?](https://discourse.vtk.org/t/how-to-catch-window-close-events/4246)

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**Author:** [@Leo843](https://discourse.vtk.org/u/Leo843)\
**Replies:** 1\
**Last updated:** [September 21, 2020, 4:31am UTC](https://discourse.vtk.org/t/how-to-catch-window-close-events/4246 "2020-09-21T04:31:53Z")

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Hi all, I discovered VTK recently and I am trying to get used to it for now. Currently I am trying to plot some 2D curves that represents the evolution of the sin and cos functions through time at a given rate. To updat…

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## [vtkImageReslice origin/direction calculation problem](https://discourse.vtk.org/t/vtkimagereslice-origin-direction-calculation-problem/4248)

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**Author:** [@guojunjie4SD](https://discourse.vtk.org/u/guojunjie4SD)\
**Replies:** 1\
**Last updated:** [September 18, 2020, 10:19pm UTC](https://discourse.vtk.org/t/vtkimagereslice-origin-direction-calculation-problem/4248 "2020-09-18T22:19:43Z")

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Sorry to bother you. I really need some help in vtkImageReslice class!!! The Problem is : I get the vtkImageData from MR dicom images. I want to get the oblique image form it by given origin and direction; Here is …

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## [vtkDistanceWidget Individual Colors for Each End](https://discourse.vtk.org/t/vtkdistancewidget-individual-colors-for-each-end/4239)

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**Author:** [@raungst](https://discourse.vtk.org/u/raungst)\
**Replies:** 1\
**Last updated:** [September 18, 2020, 9:12pm UTC](https://discourse.vtk.org/t/vtkdistancewidget-individual-colors-for-each-end/4239 "2020-09-18T21:12:01Z")

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I’m trying to use the vtkDistanceWidget as more of a vector widget to signify direction. To show the user which direction is from and to, I’m trying to set the color of each cross hair to something different. However, th…

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## [Point ordering for vtkLagrangeHexahedron?](https://discourse.vtk.org/t/point-ordering-for-vtklagrangehexahedron/4253)

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**Author:** [@RonRahaman](https://discourse.vtk.org/u/RonRahaman)\
**Replies:** 2\
**Last updated:** [September 18, 2020, 7:50pm UTC](https://discourse.vtk.org/t/point-ordering-for-vtklagrangehexahedron/4253 "2020-09-18T19:50:22Z")

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I’m interested in using vtkLagrangeHexahedrons for my app (a spectral element simulation). I’ve written a simple example, but the surfaces look funky. This is a 3rd order hex, and it’s labeled with the vertex IDs. I’v…

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## [Render a yuv420 encoded Image.](https://discourse.vtk.org/t/render-a-yuv420-encoded-image/4249)

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**Author:** [@Seekerp](https://discourse.vtk.org/u/Seekerp)\
**Replies:** 1\
**Last updated:** [September 18, 2020, 5:08pm UTC](https://discourse.vtk.org/t/render-a-yuv420-encoded-image/4249 "2020-09-18T17:08:04Z")

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Hi guys. I am receiving a Yuv420 buffer as a Uint8Array. I want to render this as Image data with vtk.js i.e const values = yuv420Buffer var scalars = vtkDataArray.newInstance({ values: values, numberOfCompone…

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## [The vtkResliceImageViewer and the vtkResliceCursorRepresentation reslicer has different output](https://discourse.vtk.org/t/the-vtkresliceimageviewer-and-the-vtkreslicecursorrepresentation-reslicer-has-different-output/1774)

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**Author:** [@kohit](https://discourse.vtk.org/u/kohit)\
**Replies:** 5\
**Last updated:** [September 18, 2020, 12:47pm UTC](https://discourse.vtk.org/t/the-vtkresliceimageviewer-and-the-vtkreslicecursorrepresentation-reslicer-has-different-output/1774 "2020-09-18T12:47:00Z")

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Hi, I am using vtkResliceImageViewer follow the FourPaneViewer example, However, when I am using GetRepresentation()-\>GetReslice()-\>GetOutput(), sometimes the output image is different from the viewer output (mainly the…

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## [Volume cannot display in in iOS](https://discourse.vtk.org/t/volume-cannot-display-in-in-ios/2807)

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**Author:** [@cocacc](https://discourse.vtk.org/u/cocacc)\
**Replies:** 1\
**Last updated:** [September 18, 2020, 2:44am UTC](https://discourse.vtk.org/t/volume-cannot-display-in-in-ios/2807 "2020-09-18T02:44:31Z")

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I want to display Volume in iPhone (iPhone xR os 13.4 Xcode 11.3.1 VTK 8.2.0） I use Examples /VTK-8.2.0/Examples/iOS/VolumeRender but I got the error message： Generic Warning: In /VTK-8.2.0/Rendering/OpenGL2/vtkOpen…

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## [vtkTriangleFilter - Generate more triangles?](https://discourse.vtk.org/t/vtktrianglefilter-generate-more-triangles/4169)

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**Author:** [@MMoussa](https://discourse.vtk.org/u/MMoussa)\
**Replies:** 4\
**Last updated:** [September 17, 2020, 11:35pm UTC](https://discourse.vtk.org/t/vtktrianglefilter-generate-more-triangles/4169 "2020-09-17T23:35:58Z")

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I am using vtkTraingleFilter to triangulate a vtkUnstructuredGrid. My goal is to generate a smooth color map. My understanding is that I need more triangles to do this. For example a linear quadrilateral is rendered wi…

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## [VTU and VTK extension files](https://discourse.vtk.org/t/vtu-and-vtk-extension-files/4240)

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**Author:** [@Luis\_Carlos\_Carneiro](https://discourse.vtk.org/u/Luis_Carlos_Carneiro)\
**Replies:** 1\
**Last updated:** [September 17, 2020, 11:31pm UTC](https://discourse.vtk.org/t/vtu-and-vtk-extension-files/4240 "2020-09-17T23:31:00Z")

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Dear All, Does .vtk extension files support volumetric (Tetrahedral) meshes? If so, where it can be found the specifications. Where it can be found the specifications of .vtu files? Thanks in Advance, Luis Gonçalves …

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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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## [Transform matrix of vtkboxwidget2 is different calculated](https://discourse.vtk.org/t/transform-matrix-of-vtkboxwidget2-is-different-calculated/4235)

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**Author:** [@zandarina](https://discourse.vtk.org/u/zandarina)\
**Replies:** 0\
**Last updated:** [September 17, 2020, 7:54am UTC](https://discourse.vtk.org/t/transform-matrix-of-vtkboxwidget2-is-different-calculated/4235 "2020-09-17T07:54:35Z")

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Hello, I amb trying to understand the transformation matrix of the vtkboxwidget2. I want to have a bounding box widget with only translations. In some transformations the matrix gives the initial position and updates it…

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## [add observer on cell and point array](https://discourse.vtk.org/t/add-observer-on-cell-and-point-array/4202)

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**Author:** [@bistek](https://discourse.vtk.org/u/bistek)\
**Replies:** 3\
**Last updated:** [September 17, 2020, 11:56am UTC](https://discourse.vtk.org/t/add-observer-on-cell-and-point-array/4202 "2020-09-17T11:56:43Z")

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Hello, I have a polydata and I would like to run some callback function when the polydata in general, its cells or its points are modified. I attach the following test code as an example. # define points x = \[0.0, 0.0, …

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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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## [How write a own template class which inherits from an existing vtk class](https://discourse.vtk.org/t/how-write-a-own-template-class-which-inherits-from-an-existing-vtk-class/4195)

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**Author:** [@Amnesie](https://discourse.vtk.org/u/Amnesie)\
**Replies:** 5\
**Last updated:** [September 16, 2020, 2:36pm UTC](https://discourse.vtk.org/t/how-write-a-own-template-class-which-inherits-from-an-existing-vtk-class/4195 "2020-09-16T14:36:18Z")

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Hi everyone, I want to write a template class in vtk ,which inherits from an existing vtk class. I use this ReadDICOMSeries as example. Assuming I’m not sure the data type of \_ImageViewer,maybe vtkResliceImageViewer…

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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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## [request hundreds images by http](https://discourse.vtk.org/t/request-hundreds-images-by-http/4154)

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**Author:** [@mqwang](https://discourse.vtk.org/u/mqwang)\
**Replies:** 18\
**Last updated:** [September 16, 2020, 5:16am UTC](https://discourse.vtk.org/t/request-hundreds-images-by-http/4154 "2020-09-16T05:16:50Z")

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Hi All, I use vtk-js and which reader should I use to request hundreds of dicom images by http? And is there any concrete example ? Many thanks!

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## [How to add an icon like this ?](https://discourse.vtk.org/t/how-to-add-an-icon-like-this/4220)

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**Author:** [@xuexl](https://discourse.vtk.org/u/xuexl)\
**Replies:** 2\
**Last updated:** [September 16, 2020, 1:15am UTC](https://discourse.vtk.org/t/how-to-add-an-icon-like-this/4220 "2020-09-16T01:15:37Z")

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I want to add an icon in the 3d world, and the position of it in the world is fixed, but the size of the icon is fixed too. That is to say, when zooming the model, the icon is not zoomed. but when moving the model, the…

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## [VTK Examples, modernising the code](https://discourse.vtk.org/t/vtk-examples-modernising-the-code/4218)

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**Author:** [@amaclean](https://discourse.vtk.org/u/amaclean)\
**Replies:** 3\
**Last updated:** [September 15, 2020, 5:04pm UTC](https://discourse.vtk.org/t/vtk-examples-modernising-the-code/4218 "2020-09-15T17:04:12Z")

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Just letting you all know that I am beginning a process of modernising the C++ VTK examples. My initial approach will be to move from vtkSmartPointer to vtkNew where appropriate, use vtkNamedColors, use auto where appro…

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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)

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**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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## [ProbeFilter not producing the correct result](https://discourse.vtk.org/t/probefilter-not-producing-the-correct-result/4151)

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**Author:** [@isuruwi](https://discourse.vtk.org/u/isuruwi)\
**Replies:** 2\
**Last updated:** [September 15, 2020, 2:03pm UTC](https://discourse.vtk.org/t/probefilter-not-producing-the-correct-result/4151 "2020-09-15T14:03:00Z")

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I have created a 3D volumetric mesh and saved it as a vtkUnstrcturedGrid (i.e. as a .vtk file). This mesh consists of a box with an ellipsoid where the ellipsoid is inside of this box. This mesh has two scalars where the…

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## [Rendering a 2D float array.](https://discourse.vtk.org/t/rendering-a-2d-float-array/4216)

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**Author:** [@Seekerp](https://discourse.vtk.org/u/Seekerp)\
**Replies:** 1\
**Last updated:** [September 14, 2020, 9:53pm UTC](https://discourse.vtk.org/t/rendering-a-2d-float-array/4216 "2020-09-14T21:53:11Z")

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Hi everyone. Is there an example I can learn from that shows how to render an RGB float array in VTK.js. The closest I could find in 2D rendering is this: https://kitware.github.io/vtk-js/examples/ImageMapper.html, but t…

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## [WebGL2 issue](https://discourse.vtk.org/t/webgl2-issue/4176)

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**Author:** [@samm-vs](https://discourse.vtk.org/u/samm-vs)\
**Replies:** 7\
**Last updated:** [September 14, 2020, 3:20pm UTC](https://discourse.vtk.org/t/webgl2-issue/4176 "2020-09-14T15:20:27Z")

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I am close to finishing my application but I didn’t realize the difference in WebGL that safari uses to compare to Google Chrome. Now as I try to test with chrome and firefox, the coloring scheme is off. Is there a way t…

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## ["Unable to eglMakeCurrent" when using vtkEGLRenderWindow](https://discourse.vtk.org/t/unable-to-eglmakecurrent-when-using-vtkeglrenderwindow/4211)

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**Author:** [@jonoweideman](https://discourse.vtk.org/u/jonoweideman)\
**Replies:** 4\
**Last updated:** [September 14, 2020, 2:47pm UTC](https://discourse.vtk.org/t/unable-to-eglmakecurrent-when-using-vtkeglrenderwindow/4211 "2020-09-14T14:47:39Z")

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Hi there. I’m attempting to build a client server application where a user can request high resolution renders of a data cube from various camera positions. The request contain information about the camera such as Positi…

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## [Descriptions of generated streamtracer attributes](https://discourse.vtk.org/t/descriptions-of-generated-streamtracer-attributes/4206)

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**Author:** [@Samuel\_James](https://discourse.vtk.org/u/Samuel_James)\
**Replies:** 1\
**Last updated:** [September 14, 2020, 7:28am UTC](https://discourse.vtk.org/t/descriptions-of-generated-streamtracer-attributes/4206 "2020-09-14T07:28:38Z")

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Hi all, When integrating a streamline the streamtracer generates attributes angular velocity, rotation, and vorticity. Are there any documented descriptions of these attributes or how they are derived? Thanks, Sam

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