# Support

**URL:** https://discourse.vtk.org/c/support/6.md?page=123

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

**Page:** 124

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## [Multivolume Rendering Crashing (Python wrap, v8.2.0)](https://discourse.vtk.org/t/multivolume-rendering-crashing-python-wrap-v8-2-0/4028)

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**Author:** [@yang613](https://discourse.vtk.org/u/yang613)\
**Replies:** 0\
**Last updated:** [August 19, 2020, 11:51pm UTC](https://discourse.vtk.org/t/multivolume-rendering-crashing-python-wrap-v8-2-0/4028 "2020-08-19T23:51:05Z")

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Hi everyone, I’m a beginner at VTK (using the Python wrapping) and am currently having a bug where the program silently crashes when vtk.vtkRenderWindow.Render() is called. Currently I’m running the following code on m…

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## [How to catch errors in VTK](https://discourse.vtk.org/t/how-to-catch-errors-in-vtk/1100)

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**Author:** [@kit](https://discourse.vtk.org/u/kit)\
**Replies:** 6\
**Last updated:** [August 19, 2020, 9:48pm UTC](https://discourse.vtk.org/t/how-to-catch-errors-in-vtk/1100 "2020-08-19T21:48:09Z")

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Are there some examples / best practices for catching errors in VTK? The scenario I have is creating unit tests for a custom VTK filter, to make sure it catches cases where bad data is input, something like: vtkSmartPo…

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## [Checking if the rendering was successful](https://discourse.vtk.org/t/checking-if-the-rendering-was-successful/3999)

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**Author:** [@mykolav](https://discourse.vtk.org/u/mykolav)\
**Replies:** 7\
**Last updated:** [August 19, 2020, 1:30pm UTC](https://discourse.vtk.org/t/checking-if-the-rendering-was-successful/3999 "2020-08-19T13:30:14Z")

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Hi, I’m trying to render a 3d volume. To catch error events I use ErrorObserver example. After the pipeline setup, I do ResetCamera() and Render(), but the return of the Render() function doesn’t guarantee that no error…

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## [Pulling Range data from head instead of the calculated Range](https://discourse.vtk.org/t/pulling-range-data-from-head-instead-of-the-calculated-range/4013)

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**Author:** [@samm-vs](https://discourse.vtk.org/u/samm-vs)\
**Replies:** 0\
**Last updated:** [August 18, 2020, 5:08pm UTC](https://discourse.vtk.org/t/pulling-range-data-from-head-instead-of-the-calculated-range/4013 "2020-08-18T17:08:15Z")

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Is there a way to select the range given by the meta-data for my scaler point array in vtk instead of pulling the calculated one from dataarray.getRange()? In another word how can I find the min and max of my dataset whi…

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## [How to get normal vectors on slices?](https://discourse.vtk.org/t/how-to-get-normal-vectors-on-slices/4011)

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**Author:** [@Yusuf\_Demiroglu](https://discourse.vtk.org/u/Yusuf_Demiroglu)\
**Replies:** 0\
**Last updated:** [August 18, 2020, 11:21am UTC](https://discourse.vtk.org/t/how-to-get-normal-vectors-on-slices/4011 "2020-08-18T11:21:10Z")

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Hi everyone, I am trying to find forces on a slice that taken over a surface and the total closed area in this slice. I got some scalar quantities over the surface. I need normal vectors to be multiplied to get forces. …

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## [vtkRenderWindow only works in Load Event](https://discourse.vtk.org/t/vtkrenderwindow-only-works-in-load-event/4003)

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**Author:** [@JimHewitt](https://discourse.vtk.org/u/JimHewitt)\
**Replies:** 4\
**Last updated:** [August 18, 2020, 4:11am UTC](https://discourse.vtk.org/t/vtkrenderwindow-only-works-in-load-event/4003 "2020-08-18T04:11:07Z")

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I’m trying the ReadPLY example and it works. However, when I move the call to Readply() from renderWindowControl1\_Load1 to a a button click event, it doesn’t work. Is there a way I can do this in the button click event…

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## [volume Render can't work well with shadeon in 'big' data(500 \* 1024 \* 1000 just 500mb)](https://discourse.vtk.org/t/volume-render-cant-work-well-with-shadeon-in-big-data-500-1024-1000-just-500mb/4006)

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**Author:** [@kaia](https://discourse.vtk.org/u/kaia)\
**Replies:** 0\
**Last updated:** [August 18, 2020, 2:30am UTC](https://discourse.vtk.org/t/volume-render-cant-work-well-with-shadeon-in-big-data-500-1024-1000-just-500mb/4006 "2020-08-18T02:30:31Z")

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Hi VTK experts. I am experimenting with Volume Rendering in my VTK-based C# application, and I am facing some issues with the vtkVolumeProperty shadeon. and here is some fragments taken from code run 5001024500 is…

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## [PolydataMapper vs DataSetMapper](https://discourse.vtk.org/t/polydatamapper-vs-datasetmapper/3991)

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**Author:** [@j-miguel](https://discourse.vtk.org/u/j-miguel)\
**Replies:** 2\
**Last updated:** [August 17, 2020, 4:49pm UTC](https://discourse.vtk.org/t/polydatamapper-vs-datasetmapper/3991 "2020-08-17T16:49:05Z")

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I’ve seen some examples using vtkDataSetMapper and others using vtkPolyDataMapper. (On a closer look to the vtkDataSetMapper implementation, I see that it actually creates a vtkPolyDataMapper and I noticed there is alre…

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## [Convert .vtk file into nifti format](https://discourse.vtk.org/t/convert-vtk-file-into-nifti-format/3997)

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**Author:** [@isuruwi](https://discourse.vtk.org/u/isuruwi)\
**Replies:** 3\
**Last updated:** [August 17, 2020, 4:00pm UTC](https://discourse.vtk.org/t/convert-vtk-file-into-nifti-format/3997 "2020-08-17T16:00:39Z")

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I have first created a vtkParametricEllipsoid (i.e. a surface mesh). I here used trimesh library since it contains a functionality to generate a 3D volume mesh by passing a surface mesh (for that they used gmsh library).…

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## [Save vtk file in old format](https://discourse.vtk.org/t/save-vtk-file-in-old-format/3987)

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**Author:** [@Yakov](https://discourse.vtk.org/u/Yakov)\
**Replies:** 1\
**Last updated:** [August 16, 2020, 7:24pm UTC](https://discourse.vtk.org/t/save-vtk-file-in-old-format/3987 "2020-08-16T19:24:20Z")

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If there is a way to save a file in old vtk 3.0 format(except using an old vtk version)?

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## [How can I programmatically set individual voxels?](https://discourse.vtk.org/t/how-can-i-programmatically-set-individual-voxels/3988)

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**Author:** [@inhahe](https://discourse.vtk.org/u/inhahe)\
**Replies:** 0\
**Last updated:** [August 16, 2020, 4:36pm UTC](https://discourse.vtk.org/t/how-can-i-programmatically-set-individual-voxels/3988 "2020-08-16T16:36:53Z")

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I want to do some volumetric rendering of a volume I create by setting individual points, not from loading a file and not from using primitives like the cylinder, cone, sphere, etc. How can I do this? Also, is it bad if…

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## [Create volumetric mesh](https://discourse.vtk.org/t/create-volumetric-mesh/3984)

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**Author:** [@isuruwi](https://discourse.vtk.org/u/isuruwi)\
**Replies:** 1\
**Last updated:** [August 15, 2020, 5:37pm UTC](https://discourse.vtk.org/t/create-volumetric-mesh/3984 "2020-08-15T17:37:07Z")

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I need to create a volumetric ellipsoid. VTK appears to provide a number of ways to create a mesh representing the surface of a 3D object. Therefore I used the example given in \[1\] to first create a vtkParametricEllipso…

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## [Can't access VTK classes or methods in python](https://discourse.vtk.org/t/cant-access-vtk-classes-or-methods-in-python/3913)

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**Author:** [@epaj95](https://discourse.vtk.org/u/epaj95)\
**Replies:** 1\
**Last updated:** [August 14, 2020, 4:04pm UTC](https://discourse.vtk.org/t/cant-access-vtk-classes-or-methods-in-python/3913 "2020-08-14T16:04:30Z")

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Hello all, I’m having a strange issue using VTK in python. I have created a conda environment and installed VTK 8.1 from the anaconda channel. In VScode, I’ve set the python interpreter to this conda env, and can import…

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## [How to use a Custom LookupTable, vtkThresholdPoints with vtkGlyph3DMapper](https://discourse.vtk.org/t/how-to-use-a-custom-lookuptable-vtkthresholdpoints-with-vtkglyph3dmapper/3979)

<div class="topic-metadata">

**Author:** [@Seun](https://discourse.vtk.org/u/Seun)\
**Replies:** 0\
**Last updated:** [August 14, 2020, 2:19pm UTC](https://discourse.vtk.org/t/how-to-use-a-custom-lookuptable-vtkthresholdpoints-with-vtkglyph3dmapper/3979 "2020-08-14T14:19:33Z")

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Hi everyone, I’ve got this issue working with vtkGlyph3DMapper. Basically, I’ve got a polydata populated with points of which each individual point has a value (magnitude) associated with it. This array of magnitude is …

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## [How split image data with plane form DICOM images](https://discourse.vtk.org/t/how-split-image-data-with-plane-form-dicom-images/3955)

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**Author:** [@11112](https://discourse.vtk.org/u/11112)\
**Replies:** 5\
**Last updated:** [August 14, 2020, 10:01am UTC](https://discourse.vtk.org/t/how-split-image-data-with-plane-form-dicom-images/3955 "2020-08-14T10:01:54Z")

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I already have a series of DICOM images as CT of verts, I read it with vtkDICOMReader. And use volume ray cast to transform as 3D image. Now I need to split each vert by plane, and get slice of 3 dimensions. How can I…

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## [vtk Streamlines from numpy array](https://discourse.vtk.org/t/vtk-streamlines-from-numpy-array/3977)

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**Author:** [@prateekm](https://discourse.vtk.org/u/prateekm)\
**Replies:** 0\
**Last updated:** [August 14, 2020, 8:28am UTC](https://discourse.vtk.org/t/vtk-streamlines-from-numpy-array/3977 "2020-08-14T08:28:18Z")

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I m new to vtk I want to generate vtk streamlines from data stored in numpy array …how can I do that?? Thanks in advance.

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## [How to create a gradient color shift](https://discourse.vtk.org/t/how-to-create-a-gradient-color-shift/3973)

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**Author:** [@samm-vs](https://discourse.vtk.org/u/samm-vs)\
**Replies:** 1\
**Last updated:** [August 13, 2020, 5:54pm UTC](https://discourse.vtk.org/t/how-to-create-a-gradient-color-shift/3973 "2020-08-13T17:54:09Z")

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I have scaler data for color ranging from -5.000 to 5.000 with -1000000000.0 as areas I would like to be transparent. how do I create a color transfer function or an opacity function where the flow of color from -5 to 5 …

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## [Write file in vtk format](https://discourse.vtk.org/t/write-file-in-vtk-format/3964)

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**Author:** [@Yakov](https://discourse.vtk.org/u/Yakov)\
**Replies:** 0\
**Last updated:** [August 13, 2020, 10:21am UTC](https://discourse.vtk.org/t/write-file-in-vtk-format/3964 "2020-08-13T10:21:04Z")

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I want to create vtk file with mesh The vtk should have : vtk DataFile Version 3.0 POINTS POLYGONS NORMALS I create a 3d cube object cube1 = vtk.vtkCubeSource() cube1.SetXLength(6) cube1.SetYLength(10) cube1.SetZLe…

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## [QGraphicsitems in QGraphicsscene](https://discourse.vtk.org/t/qgraphicsitems-in-qgraphicsscene/3970)

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**Author:** [@tommi](https://discourse.vtk.org/u/tommi)\
**Replies:** 0\
**Last updated:** [August 13, 2020, 1:02pm UTC](https://discourse.vtk.org/t/qgraphicsitems-in-qgraphicsscene/3970 "2020-08-13T13:02:01Z")

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Hello, i want to use Qt - QGraphicsitems in a QGraphicsscene with VTK-Support. But is seems, that QVTKGraphicsitem is no longer supportet. Is there an alternative?

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## [Visualization of 2D height point data.](https://discourse.vtk.org/t/visualization-of-2d-height-point-data/3951)

<div class="topic-metadata">

**Author:** [@NeoDreamer](https://discourse.vtk.org/u/NeoDreamer)\
**Replies:** 4\
**Last updated:** [August 13, 2020, 7:26am UTC](https://discourse.vtk.org/t/visualization-of-2d-height-point-data/3951 "2020-08-13T07:26:00Z")

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I have height point data that shape of 2D matrix. Which is best way to visualize that data.

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## [Ghost points and ExtractSurface](https://discourse.vtk.org/t/ghost-points-and-extractsurface/3901)

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**Author:** [@cchan](https://discourse.vtk.org/u/cchan)\
**Replies:** 3\
**Last updated:** [August 11, 2020, 8:44pm UTC](https://discourse.vtk.org/t/ghost-points-and-extractsurface/3901 "2020-08-11T20:44:41Z")

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Hello! I’m writing a C++ VTK filter, and I’m trying to understand the idea of ghost points and how multiblock topology works. My understanding is that in MPI mode, ExtractSurface should be ignoring boundaries between M…

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## [Show specific tissue on vtkVolume](https://discourse.vtk.org/t/show-specific-tissue-on-vtkvolume/3916)

<div class="topic-metadata">

**Author:** [@flaviu2](https://discourse.vtk.org/u/flaviu2)\
**Replies:** 5\
**Last updated:** [August 11, 2020, 5:58pm UTC](https://discourse.vtk.org/t/show-specific-tissue-on-vtkvolume/3916 "2020-08-11T17:58:41Z")

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I have a vtkVolume on a vtkRenderer, with AddRGBPoint call and AddPoint call for vtkColorTransferFunction and vtkPiecewiseFunction used for vtkVolumeProperty. Is there any possibility to color in a solid color (red or s…

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## [Where to find old vtk for Python?](https://discourse.vtk.org/t/where-to-find-old-vtk-for-python/3937)

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**Author:** [@tbillah](https://discourse.vtk.org/u/tbillah)\
**Replies:** 5\
**Last updated:** [August 11, 2020, 5:50pm UTC](https://discourse.vtk.org/t/where-to-find-old-vtk-for-python/3937 "2020-08-11T17:50:07Z")

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Hi all, vtk PyPI only has versions \>8.0.0. Is there a place where I can get vtk==7.1? I tried pip install vtk==7.1 only to run in to: Collecting vtk==7.1 ERROR: Could not find a version that satisfies the requirement…

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## [How can i use the vtkStreamtracer to generate a streamline with my unstructured grid data(vtu)](https://discourse.vtk.org/t/how-can-i-use-the-vtkstreamtracer-to-generate-a-streamline-with-my-unstructured-grid-data-vtu/790)

<div class="topic-metadata">

**Author:** [@stargazer](https://discourse.vtk.org/u/stargazer)\
**Replies:** 6\
**Last updated:** [August 11, 2020, 5:44pm UTC](https://discourse.vtk.org/t/how-can-i-use-the-vtkstreamtracer-to-generate-a-streamline-with-my-unstructured-grid-data-vtu/790 "2020-08-11T17:44:56Z")

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I\`m using VTK to visualize data coming from xflow in vtu. When I use the Paraview, it can generate the right streamline, but when I use the VTK to visualize my data, it only displays the outline and the airplane mode…

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## [Updating data input for VolumeMapper without copying data](https://discourse.vtk.org/t/updating-data-input-for-volumemapper-without-copying-data/3943)

<div class="topic-metadata">

**Author:** [@R.Engelken](https://discourse.vtk.org/u/R.Engelken)\
**Replies:** 2\
**Last updated:** [August 11, 2020, 3:29pm UTC](https://discourse.vtk.org/t/updating-data-input-for-volumemapper-without-copying-data/3943 "2020-08-11T15:29:01Z")

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Hello, I use the following pipeline: ImageData -\> SmartVolumeMapper -\> … with 1 scalar component To prevent copying data I want to retrieve a pointer to the image data array and give it to another interface If I use …

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## [Contour filter - add nodes programatically](https://discourse.vtk.org/t/contour-filter-add-nodes-programatically/1127)

<div class="topic-metadata">

**Author:** [@Andyjk1406](https://discourse.vtk.org/u/Andyjk1406)\
**Replies:** 7\
**Last updated:** [August 11, 2020, 1:48pm UTC](https://discourse.vtk.org/t/contour-filter-add-nodes-programatically/1127 "2020-08-11T13:48:49Z")

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I’m struggling to add nodes programatically. I can add one, but then things crash when I try to add a second or try to interact to add more nodes. I have modified this example with about 6 more lines near the end as sho…

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## [Issue with VTK 9.0.2 - vtk DICOM reader and viewer2](https://discourse.vtk.org/t/issue-with-vtk-9-0-2-vtk-dicom-reader-and-viewer2/3946)

<div class="topic-metadata">

**Author:** [@Balaji](https://discourse.vtk.org/u/Balaji)\
**Replies:** 2\
**Last updated:** [August 11, 2020, 4:40am UTC](https://discourse.vtk.org/t/issue-with-vtk-9-0-2-vtk-dicom-reader-and-viewer2/3946 "2020-08-11T04:40:46Z")

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Hi, I’m newbie with Qt and VTK. Here my task is to display dicom image in Qt desktop GUI application. Qt version 5.12 Vtk version 9.0.2 Window 10, VS 16 2017 I have tried with VTK example of ReadDicomseriesQt, When…

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## [Create polyline using independent color from each point](https://discourse.vtk.org/t/create-polyline-using-independent-color-from-each-point/3949)

<div class="topic-metadata">

**Author:** [@lyz](https://discourse.vtk.org/u/lyz)\
**Replies:** 0\
**Last updated:** [August 11, 2020, 1:35am UTC](https://discourse.vtk.org/t/create-polyline-using-independent-color-from-each-point/3949 "2020-08-11T01:35:40Z")

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Is there some method to create polyline using independent color from each point? each point owns the unique color. and the color of the polyline is interpolated by each point.

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## [Crashes on mac OS](https://discourse.vtk.org/t/crashes-on-mac-os/3531)

<div class="topic-metadata">

**Author:** [@codeling](https://discourse.vtk.org/u/codeling)\
**Replies:** 6\
**Last updated:** [August 10, 2020, 10:29pm UTC](https://discourse.vtk.org/t/crashes-on-mac-os/3531 "2020-08-10T22:29:12Z")

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We have a program using Qt and VTK that runs on both Windows and Linux, and which I am now trying to get running on Mac OS. I have managed to get it to build and run there, but when loading a dataset (which triggers show…

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## [Catching opengl errors](https://discourse.vtk.org/t/catching-opengl-errors/3945)

<div class="topic-metadata">

**Author:** [@mykolav](https://discourse.vtk.org/u/mykolav)\
**Replies:** 1\
**Last updated:** [August 10, 2020, 7:54pm UTC](https://discourse.vtk.org/t/catching-opengl-errors/3945 "2020-08-10T19:54:21Z")

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Hi all, what would be the recommended way to handle errors that occur inside vtk, specifically connected with opengl errors? I’m creating a volume with dimensions that exceed my available VRAM, and I get the opengl and …

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