# Support

**URL:** https://discourse.vtk.org/c/support/6.md?page=158

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

**Page:** 159

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## [How to sample implicit function in different bounds](https://discourse.vtk.org/t/how-to-sample-implicit-function-in-different-bounds/808)

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**Author:** [@Frank](https://discourse.vtk.org/u/Frank)\
**Replies:** 0\
**Last updated:** [April 22, 2019, 6:42am UTC](https://discourse.vtk.org/t/how-to-sample-implicit-function-in-different-bounds/808 "2019-04-22T06:42:39Z")

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I get a vtkImplicitFunction object and want to sample it over a structured point set. I know the approximate shape of the implicit. So I want to sample vtkImplicitFunction in different bounds(they could be overlap) and f…

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## [Problems with vtkRenderWindowInteractor on macOS using Cocoa](https://discourse.vtk.org/t/problems-with-vtkrenderwindowinteractor-on-macos-using-cocoa/805)

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**Author:** [@NoeMurr](https://discourse.vtk.org/u/NoeMurr)\
**Replies:** 2\
**Last updated:** [April 22, 2019, 2:21am UTC](https://discourse.vtk.org/t/problems-with-vtkrenderwindowinteractor-on-macos-using-cocoa/805 "2019-04-22T02:21:29Z")

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Hi all, I’m learning VTK reading the book VTKTextBook. I’ve tried to execute the Cone example at link: https://lorensen.github.io/VTKExamples/site/Cxx/GeometricObjects/Cone/ When I run it I’ve got a strange behavior …

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## [Four dipsplay Window](https://discourse.vtk.org/t/four-dipsplay-window/414)

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**Author:** [@dp1991](https://discourse.vtk.org/u/dp1991)\
**Replies:** 11\
**Last updated:** [April 22, 2019, 12:30am UTC](https://discourse.vtk.org/t/four-dipsplay-window/414 "2019-04-22T00:30:55Z")

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Hi i need to display my image into 4 window 1 axial 2- sagittal 3- coronal 4- 3D view like 3dslicer default how to do it ??

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## [displaying 3D volume in RED](https://discourse.vtk.org/t/displaying-3d-volume-in-red/804)

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**Author:** [@Marco\_Festugato](https://discourse.vtk.org/u/Marco_Festugato)\
**Replies:** 2\
**Last updated:** [April 21, 2019, 3:46pm UTC](https://discourse.vtk.org/t/displaying-3d-volume-in-red/804 "2019-04-21T15:46:07Z")

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Hi, I want to display my 3D volume (range from 0 to 255) in uniform red. I’ve thought of this code: colorTransferFunction-\> AddRGBPoint (0.0 0.0 0.0 0.0); // i don't know if with …

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## [Contour isosurfaces for positive and negative values: orientation](https://discourse.vtk.org/t/contour-isosurfaces-for-positive-and-negative-values-orientation/800)

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**Author:** [@Jellby](https://discourse.vtk.org/u/Jellby)\
**Replies:** 1\
**Last updated:** [April 20, 2019, 12:27pm UTC](https://discourse.vtk.org/t/contour-isosurfaces-for-positive-and-negative-values-orientation/800 "2019-04-20T12:27:25Z")

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I have some scalar field for which I want to represent contours for +v and -v simultaneously, with different colors, with the caveat that the contours for -v should be “reversed”, i.e., they enclose the volume for which …

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## [ResliceImageViewer for MPR](https://discourse.vtk.org/t/resliceimageviewer-for-mpr/799)

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**Author:** [@Marco\_Festugato](https://discourse.vtk.org/u/Marco_Festugato)\
**Replies:** 0\
**Last updated:** [April 20, 2019, 8:11am UTC](https://discourse.vtk.org/t/resliceimageviewer-for-mpr/799 "2019-04-20T08:11:32Z")

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Hi all, I’m trying to figure it out how this class works. I have a 3D volume of which i want to perform MPR (like in the image below) I think I have to use the vtkResliceImageViewer but I dont understand how it works…

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## [Simulating stereo vision using VTK](https://discourse.vtk.org/t/simulating-stereo-vision-using-vtk/780)

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**Author:** [@abaldur](https://discourse.vtk.org/u/abaldur)\
**Replies:** 5\
**Last updated:** [April 19, 2019, 10:57pm UTC](https://discourse.vtk.org/t/simulating-stereo-vision-using-vtk/780 "2019-04-19T22:57:19Z")

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Hi Suppose I want to use VTK to simulate a stereo vision system composed of a line laser and a camera. The laser is capable of projecting a uniform line beam onto some 3D geometry, which I have in the form of an STL f…

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## [vtkImageResliceMapper and BorderOff() / BorderOn()](https://discourse.vtk.org/t/vtkimagereslicemapper-and-borderoff-borderon/794)

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**Author:** [@jonklingensmith](https://discourse.vtk.org/u/jonklingensmith)\
**Replies:** 0\
**Last updated:** [April 19, 2019, 5:25pm UTC](https://discourse.vtk.org/t/vtkimagereslicemapper-and-borderoff-borderon/794 "2019-04-19T17:25:05Z")

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I am trying to get a thin, colored border line - color coded to indicate axial, sagittal, and coronal - on the edge of 3 typical orthogonal cut planes through an image volume. It looks like I can possibly use vtkCutter()…

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## [How to get a reasonably good triangulated surface from a level-set volumetric field](https://discourse.vtk.org/t/how-to-get-a-reasonably-good-triangulated-surface-from-a-level-set-volumetric-field/765)

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**Author:** [@rdbisme](https://discourse.vtk.org/u/rdbisme)\
**Replies:** 2\
**Last updated:** [April 19, 2019, 11:59am UTC](https://discourse.vtk.org/t/how-to-get-a-reasonably-good-triangulated-surface-from-a-level-set-volumetric-field/765 "2019-04-19T11:59:28Z")

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Hello, I’m exploring some algorithms to compute curvatures on surfaces and I’m using VTK under the hoods to manage the triangulation of a level-set surface (and data structures). The problem I’m encountering is a relati…

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## [mpr](https://discourse.vtk.org/t/mpr/782)

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**Author:** [@Marco\_Festugato](https://discourse.vtk.org/u/Marco_Festugato)\
**Replies:** 2\
**Last updated:** [April 18, 2019, 5:04pm UTC](https://discourse.vtk.org/t/mpr/782 "2019-04-18T17:04:53Z")

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Hi guys! I want to perform MPR on my 3D volume…how could I do that? Which classes should i use? Is there any example (i dont find any…). Thanks in advance!

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## [Change the colour of the background of vtkImageReslice for areas out of the region of the surface](https://discourse.vtk.org/t/change-the-colour-of-the-background-of-vtkimagereslice-for-areas-out-of-the-region-of-the-surface/776)

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**Author:** [@zandarina](https://discourse.vtk.org/u/zandarina)\
**Replies:** 0\
**Last updated:** [April 18, 2019, 11:16am UTC](https://discourse.vtk.org/t/change-the-colour-of-the-background-of-vtkimagereslice-for-areas-out-of-the-region-of-the-surface/776 "2019-04-18T11:16:32Z")

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Hi everybody, I have a doubt, i am getting certain planes of a surface with vtkImageReslice but i found that these regions outside the volume are painted in a weird colour different to black. I read that there is a bug …

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## [How to create a cylinder implicit with specified height](https://discourse.vtk.org/t/how-to-create-a-cylinder-implicit-with-specified-height/681)

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**Author:** [@Frank](https://discourse.vtk.org/u/Frank)\
**Replies:** 4\
**Last updated:** [April 14, 2019, 3:40am UTC](https://discourse.vtk.org/t/how-to-create-a-cylinder-implicit-with-specified-height/681 "2019-04-14T03:40:28Z")

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I want to create a implicit cylinder with specified height. From VTK doc, it says The cylinder is infinite in extent. To truncate the cylinder in modeling operations use the vtkImplicitBoolean in combination with clippin…

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## [Labels in VTK js for annotations in image slice](https://discourse.vtk.org/t/labels-in-vtk-js-for-annotations-in-image-slice/685)

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**Author:** [@Andrzej\_Marciniak](https://discourse.vtk.org/u/Andrzej_Marciniak)\
**Replies:** 1\
**Last updated:** [April 17, 2019, 5:38pm UTC](https://discourse.vtk.org/t/labels-in-vtk-js-for-annotations-in-image-slice/685 "2019-04-17T17:38:25Z")

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Hi all, Is there any way to add annotations using vtkLabelWidget (or something else) which will work in a way that annotation is visible only on a particular slice? More precisely, is it possible to “attach” label to a …

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## [How to remove the cut of the appended planes around a curve in vtkImageReslice](https://discourse.vtk.org/t/how-to-remove-the-cut-of-the-appended-planes-around-a-curve-in-vtkimagereslice/773)

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**Author:** [@zandarina](https://discourse.vtk.org/u/zandarina)\
**Replies:** 0\
**Last updated:** [April 17, 2019, 10:00am UTC](https://discourse.vtk.org/t/how-to-remove-the-cut-of-the-appended-planes-around-a-curve-in-vtkimagereslice/773 "2019-04-17T10:00:07Z")

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Dear all, I have implemented with vtkImageReslice, the append of all especific planes around a curve. It works perfect but i realized that we can see where the cut of the plane is applied: plane 1 appended to plane 2 a…

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## [vtkWarpVector does not work. Any possible bug?](https://discourse.vtk.org/t/vtkwarpvector-does-not-work-any-possible-bug/745)

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**Author:** [@zandarina](https://discourse.vtk.org/u/zandarina)\
**Replies:** 6\
**Last updated:** [April 17, 2019, 9:51am UTC](https://discourse.vtk.org/t/vtkwarpvector-does-not-work-any-possible-bug/745 "2019-04-17T09:51:21Z")

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Dear all, I want to scale the spline from its center as an offset (the same it does with the right mouse but we do not have access to use this function). I have tried many ways with no success. I have checked this vtkWa…

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## [No shadows](https://discourse.vtk.org/t/no-shadows/767)

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**Author:** [@graphicsmonkey](https://discourse.vtk.org/u/graphicsmonkey)\
**Replies:** 0\
**Last updated:** [April 17, 2019, 3:27am UTC](https://discourse.vtk.org/t/no-shadows/767 "2019-04-17T03:27:27Z")

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I’m trying to get shadows to work with no luck yet. I added the following code based on some of the examples but i’m not seeing anything change. Is there something missing? Many thanks. auto shadows = vtkSmartPointer\<…

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## [parallel rendering in python](https://discourse.vtk.org/t/parallel-rendering-in-python/761)

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**Author:** [@clairecita](https://discourse.vtk.org/u/clairecita)\
**Replies:** 1\
**Last updated:** [April 16, 2019, 5:06pm UTC](https://discourse.vtk.org/t/parallel-rendering-in-python/761 "2019-04-16T17:06:59Z")

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Hi, I am trying to do parallele rendering in python but I am having trouble finding a solution. Neither vtkParallelRenderManager() nor vtkCompositeManager() work in python. Does anybody have another solution ?

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## [Python wrapped library and VTK 8.2.0](https://discourse.vtk.org/t/python-wrapped-library-and-vtk-8-2-0/763)

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**Author:** [@kit](https://discourse.vtk.org/u/kit)\
**Replies:** 0\
**Last updated:** [April 16, 2019, 11:52am UTC](https://discourse.vtk.org/t/python-wrapped-library-and-vtk-8-2-0/763 "2019-04-16T11:52:05Z")

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Hi, I have a library which links against VTK and uses the python wrapping when I try to compile it against version 8.2.0 it breaks at the python wrapping stage. Would be correct in thinking there are some changes in thi…

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## [Adding metadata to a vtkOpenGLActor](https://discourse.vtk.org/t/adding-metadata-to-a-vtkopenglactor/762)

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**Author:** [@msmerps](https://discourse.vtk.org/u/msmerps)\
**Replies:** 3\
**Last updated:** [April 15, 2019, 8:53pm UTC](https://discourse.vtk.org/t/adding-metadata-to-a-vtkopenglactor/762 "2019-04-15T20:53:23Z")

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Hi VTK experts, I would like to add some metadata, a string, to a vtkActor (more specifically a vtkOpenGLActor) so that when a user clicks on it, I can use the metadata to identify what the object represents and act app…

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## [Mark area in display space](https://discourse.vtk.org/t/mark-area-in-display-space/760)

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**Author:** [@pettaa123](https://discourse.vtk.org/u/pettaa123)\
**Replies:** 0\
**Last updated:** [April 15, 2019, 1:44pm UTC](https://discourse.vtk.org/t/mark-area-in-display-space/760 "2019-04-15T13:44:54Z")

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Any suggestions how to draw a rectangle or circle into display space, in order to mark an area in my 3D rendered scene? Something like this

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## [Permanent smooth Rotation of actors](https://discourse.vtk.org/t/permanent-smooth-rotation-of-actors/670)

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**Author:** [@pettaa123](https://discourse.vtk.org/u/pettaa123)\
**Replies:** 4\
**Last updated:** [April 15, 2019, 12:09pm UTC](https://discourse.vtk.org/t/permanent-smooth-rotation-of-actors/670 "2019-04-15T12:09:59Z")

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I would like to add smooth permanent Rotation to some actors. Is there an Example on how to achieve this? I think I could listen to a Rendered Event

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## [How to find the main axis normal of a vtkCylinderSource?](https://discourse.vtk.org/t/how-to-find-the-main-axis-normal-of-a-vtkcylindersource/722)

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**Author:** [@siaeleni](https://discourse.vtk.org/u/siaeleni)\
**Replies:** 5\
**Last updated:** [April 15, 2019, 6:59am UTC](https://discourse.vtk.org/t/how-to-find-the-main-axis-normal-of-a-vtkcylindersource/722 "2019-04-15T06:59:54Z")

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Hello, I was wondering how can I get the main axis as a vector of the vtkCylinderSource? Any help is really appreciated.

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## [Trying to write VTU files from fortran](https://discourse.vtk.org/t/trying-to-write-vtu-files-from-fortran/470)

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**Author:** [@vrkssai](https://discourse.vtk.org/u/vrkssai)\
**Replies:** 4\
**Last updated:** [April 14, 2019, 4:26pm UTC](https://discourse.vtk.org/t/trying-to-write-vtu-files-from-fortran/470 "2019-04-14T16:26:20Z")

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I’m trying to write a VTU file in fortran. I had prior experience writing binary vtk legacy files using fortran, I’m using the same logic to write the VTU files. But the binary files byte order seems to be a problem, bec…

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## [Error while enabling the vtkDICOM module in VTK 8.2.0](https://discourse.vtk.org/t/error-while-enabling-the-vtkdicom-module-in-vtk-8-2-0/753)

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**Author:** [@chenjianyyzz](https://discourse.vtk.org/u/chenjianyyzz)\
**Replies:** 0\
**Last updated:** [April 13, 2019, 1:07am UTC](https://discourse.vtk.org/t/error-while-enabling-the-vtkdicom-module-in-vtk-8-2-0/753 "2019-04-13T01:07:34Z")

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I try to enable the vtkDICOM module in VTK 8.2.0, I set the Module vtkDICOM option for the cmake cache: cmake -D Module\_vtkDICOM :BOOL=ON …/vtk -source then I got the warning: CMake Warning: \*\* Manually-specifi…

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## [Error with inserting vertex cells](https://discourse.vtk.org/t/error-with-inserting-vertex-cells/750)

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**Author:** [@Frank](https://discourse.vtk.org/u/Frank)\
**Replies:** 2\
**Last updated:** [April 12, 2019, 1:56pm UTC](https://discourse.vtk.org/t/error-with-inserting-vertex-cells/750 "2019-04-12T13:56:38Z")

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I want to create a polyData with lots of vertex. So I followed example auto vertexes = vtkSmartPointer\<vtkCellArray\>::New(); for (int i = 0; i \< data-\>GetNumberOfPoints(); i++) { auto vertex = vtkSmartPointer\<vtkVer…

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## [Building VTK for Arm64 with OpenGL ES](https://discourse.vtk.org/t/building-vtk-for-arm64-with-opengl-es/707)

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**Author:** [@adamrankin](https://discourse.vtk.org/u/adamrankin)\
**Replies:** 5\
**Last updated:** [April 12, 2019, 1:31pm UTC](https://discourse.vtk.org/t/building-vtk-for-arm64-with-opengl-es/707 "2019-04-12T13:31:58Z")

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Hello, I am trying to build VTK on FriendlyDesktop (Ubuntu flavour) on my NanoPC-T4, and am running into a build error. /home/pi/devel/PB-x64/Deps/vtk/GUISupport/Qt/QVTKOpenGLNativeWidget.cxx: In member function ‘virtu…

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## [VTK 8.2.0 + Qt 5.12.2 weird event queue processing](https://discourse.vtk.org/t/vtk-8-2-0-qt-5-12-2-weird-event-queue-processing/740)

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**Author:** [@Andrei\_Ivanov](https://discourse.vtk.org/u/Andrei_Ivanov)\
**Replies:** 5\
**Last updated:** [April 12, 2019, 12:41pm UTC](https://discourse.vtk.org/t/vtk-8-2-0-qt-5-12-2-weird-event-queue-processing/740 "2019-04-12T12:41:35Z")

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Dear all! I installed VTK 8.2.0 + Qt 5.12.2 and noticed a weird behavior: all my Qt programs that previously was working now crash at the moment of vtkRenderer creation if I build them in -DCMAKE\_BUILD\_TYPE=Release. I…

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## [Dynamically change position of Axes](https://discourse.vtk.org/t/dynamically-change-position-of-axes/691)

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**Author:** [@fern17](https://discourse.vtk.org/u/fern17)\
**Replies:** 1\
**Last updated:** [April 12, 2019, 10:51am UTC](https://discourse.vtk.org/t/dynamically-change-position-of-axes/691 "2019-04-12T10:51:04Z")

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Hello. I’m trying to control the position of the Axes (vtkOrientationMarkerWidget). In our interface, there should be an option to change the position with 4 possible values: Bottom left, bottom right, top left, top ri…

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## [how to apply CT Presets and LUT simultaneously using vtkimageviewer2](https://discourse.vtk.org/t/how-to-apply-ct-presets-and-lut-simultaneously-using-vtkimageviewer2/726)

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**Author:** [@Aravind](https://discourse.vtk.org/u/Aravind)\
**Replies:** 0\
**Last updated:** [April 10, 2019, 9:09am UTC](https://discourse.vtk.org/t/how-to-apply-ct-presets-and-lut-simultaneously-using-vtkimageviewer2/726 "2019-04-10T09:09:29Z")

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Hello - I am building an application where by I have the options to apply LUT as well as CT Presets. I am using vtkimageviewer2 for rendering the slices and I am using a nii image reader. Not sure if what I am doing is…

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## [vtkImageMapper + vtkActor2D show up as black](https://discourse.vtk.org/t/vtkimagemapper-vtkactor2d-show-up-as-black/744)

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**Author:** [@estan](https://discourse.vtk.org/u/estan)\
**Replies:** 1\
**Last updated:** [April 12, 2019, 9:25am UTC](https://discourse.vtk.org/t/vtkimagemapper-vtkactor2d-show-up-as-black/744 "2019-04-12T09:25:46Z")

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Hi all, I’m struggling with getting a vtkImageMapper + vtkActor2D to show up correctly. It’s showing up in black when I expect it to be all red. Test Case #!/usr/bin/env python from vtk import ( vtkImageData, …

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