# Support

**URL:** https://discourse.vtk.org/c/support/6.md?page=32

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

**Page:** 33

---

## [Inverted perspective divide in VTK](https://discourse.vtk.org/t/inverted-perspective-divide-in-vtk/13061)

<div class="topic-metadata">

**Author:** [@Daan\_Baas](https://discourse.vtk.org/u/Daan_Baas)\
**Replies:** 13\
**Last updated:** [January 18, 2024, 2:16pm UTC](https://discourse.vtk.org/t/inverted-perspective-divide-in-vtk/13061 "2024-01-18T14:16:09Z")

</div>

Hello everybody, With vtkCamera, we can use perspective projection and orthographic projection. As I understand it -when using perpective projection- a 4x4 projection matrix is set up which copies the z-values into the …

---

## [Potential bug in vtkDataAssembly?](https://discourse.vtk.org/t/potential-bug-in-vtkdataassembly/7216)

<div class="topic-metadata">

**Author:** [@scotsman60](https://discourse.vtk.org/u/scotsman60)\
**Replies:** 5\
**Last updated:** [January 18, 2024, 8:38am UTC](https://discourse.vtk.org/t/potential-bug-in-vtkdataassembly/7216 "2024-01-18T08:38:23Z")

</div>

I’m using Python 3.9 and vtk 9.1.0 on Windows. vtkDataAssembly.SelectNodes() selects nodes in the vtkDataAssembly using a ‘/’ sperated path of the node names. This method is supposed to return an empty vector/tuple if …

---

## [Rotation in a strict axis](https://discourse.vtk.org/t/rotation-in-a-strict-axis/13081)

<div class="topic-metadata">

**Author:** [@abrahamezzeddine](https://discourse.vtk.org/u/abrahamezzeddine)\
**Replies:** 1\
**Last updated:** [January 17, 2024, 3:54pm UTC](https://discourse.vtk.org/t/rotation-in-a-strict-axis/13081 "2024-01-17T15:54:23Z")

</div>

Hello I am wondering if there exists some kind of method with vtk to limit the rotation on an object, say point cloud to strictly to one axis when for example dragging left to right and up to down? The problem is that …

---

## [How to read dicom image via URL link](https://discourse.vtk.org/t/how-to-read-dicom-image-via-url-link/13086)

<div class="topic-metadata">

**Author:** [@dbtruong](https://discourse.vtk.org/u/dbtruong)\
**Replies:** 2\
**Last updated:** [January 17, 2024, 3:35pm UTC](https://discourse.vtk.org/t/how-to-read-dicom-image-via-url-link/13086 "2024-01-17T15:35:42Z")

</div>

Hello. I want to read a dicom image from a storage via URL and display it on the screen. Is there any way to do that?

---

## [How do I get the surface area of vtkUnstructuredGrid](https://discourse.vtk.org/t/how-do-i-get-the-surface-area-of-vtkunstructuredgrid/13043)

<div class="topic-metadata">

**Author:** [@nanoahSR](https://discourse.vtk.org/u/nanoahSR)\
**Replies:** 3\
**Last updated:** [January 17, 2024, 9:53am UTC](https://discourse.vtk.org/t/how-do-i-get-the-surface-area-of-vtkunstructuredgrid/13043 "2024-01-17T09:53:42Z")

</div>

Hello, I neel get surface area of vtkUnstructuredGrid, and vtkTriangleFilter is used to process VTKUnstructuredgrid, and then vtkMassProperties is used to get the surface area, but the obtained area is 0. Here is my co…

---

## [Definition conflict](https://discourse.vtk.org/t/definition-conflict/13078)

<div class="topic-metadata">

**Author:** [@Ellen-D216](https://discourse.vtk.org/u/Ellen-D216)\
**Replies:** 2\
**Last updated:** [January 17, 2024, 1:54am UTC](https://discourse.vtk.org/t/definition-conflict/13078 "2024-01-17T01:54:10Z")

</div>

I want to visualize the result of RTK with VTK. However there is a definition conflicts in vtkMath.h and lp\_lib.h. The FULL name is defined repeatedly in both header files. What should I do about it?

---

## [vtkTriangle fails with assertion 'Arrived in a branch thought to be dead' when called from FindClosestPoint](https://discourse.vtk.org/t/vtktriangle-fails-with-assertion-arrived-in-a-branch-thought-to-be-dead-when-called-from-findclosestpoint/13066)

<div class="topic-metadata">

**Author:** [@NathanaelJ](https://discourse.vtk.org/u/NathanaelJ)\
**Replies:** 3\
**Last updated:** [January 16, 2024, 12:38pm UTC](https://discourse.vtk.org/t/vtktriangle-fails-with-assertion-arrived-in-a-branch-thought-to-be-dead-when-called-from-findclosestpoint/13066 "2024-01-16T12:38:31Z")

</div>

I’m using vtk objects on several parallel MPI processes for some computations (the vtk objects are launched locally on each process so should never interact with one another). Under certain conditions, and when operating…

---

## [Build VTK 9.3.0 Msys2/Mingw64 on Win10 with OSMESA offscreen rendering](https://discourse.vtk.org/t/build-vtk-9-3-0-msys2-mingw64-on-win10-with-osmesa-offscreen-rendering/13060)

<div class="topic-metadata">

**Author:** [@tsobiech](https://discourse.vtk.org/u/tsobiech)\
**Replies:** 1\
**Last updated:** [January 16, 2024, 11:12am UTC](https://discourse.vtk.org/t/build-vtk-9-3-0-msys2-mingw64-on-win10-with-osmesa-offscreen-rendering/13060 "2024-01-16T11:12:37Z")

</div>

Description / Steps to reproduce the issue I want to compile vtk with OSMESA offscreen rendering, instead of default Win32 OpenGL. I based on package from the official repository VTK In the file PKGBUILD, I only added …

---

## [vtkValuePass - Depth Issues](https://discourse.vtk.org/t/vtkvaluepass-depth-issues/13071)

<div class="topic-metadata">

**Author:** [@Kai](https://discourse.vtk.org/u/Kai)\
**Replies:** 0\
**Last updated:** [January 15, 2024, 8:44am UTC](https://discourse.vtk.org/t/vtkvaluepass-depth-issues/13071 "2024-01-15T08:44:19Z")

</div>

Dear VTK Forum, I am encountering a challenge while working with vtkValuePass and have uncertainties regarding the depth value computation. I expect the depth values to behave similarly to the geometric coordinates they…

---

## [How can I show which actor(arrow) is above which actor on the screen.](https://discourse.vtk.org/t/how-can-i-show-which-actor-arrow-is-above-which-actor-on-the-screen/13038)

<div class="topic-metadata">

**Author:** [@thecoderMCV](https://discourse.vtk.org/u/thecoderMCV)\
**Replies:** 4\
**Last updated:** [January 14, 2024, 5:26am UTC](https://discourse.vtk.org/t/how-can-i-show-which-actor-arrow-is-above-which-actor-on-the-screen/13038 "2024-01-14T05:26:34Z")

</div>

Something like this: axis is standing on the actor here. But when I do it, it looks like below. So I don’t want it to be in it, I want it to be on it. How can I do this in Python.

---

## [Python script to read VTK legacy file format](https://discourse.vtk.org/t/python-script-to-read-vtk-legacy-file-format/13064)

<div class="topic-metadata">

**Author:** [@martinlicht](https://discourse.vtk.org/u/martinlicht)\
**Replies:** 1\
**Last updated:** [January 13, 2024, 11:18pm UTC](https://discourse.vtk.org/t/python-script-to-read-vtk-legacy-file-format/13064 "2024-01-13T23:18:36Z")

</div>

Suppose I have got a (non-binary) .vtk file in Simple Legacy Format, as in: I am looking for a Python script that reads this file and represents it as a data structure. No further processing or visualization needed at …

---

## [vtkPolyData actor behaviour is changed in VTK \>= 9.1](https://discourse.vtk.org/t/vtkpolydata-actor-behaviour-is-changed-in-vtk-9-1/13037)

<div class="topic-metadata">

**Author:** [@Edoardo\_Pasca](https://discourse.vtk.org/u/Edoardo_Pasca)\
**Replies:** 9\
**Last updated:** [January 13, 2024, 3:28pm UTC](https://discourse.vtk.org/t/vtkpolydata-actor-behaviour-is-changed-in-vtk-9-1/13037 "2024-01-13T15:28:13Z")

</div>

Hi all, In my application I show slices of vtkImageData with orthogonal view, i.e. with the camera looking at slices on the XY, XZ or YZ plane along the normal to the slice plane). On the scene I add other 3D actors fr…

---

## [vtkClipPolyData incorrectly work](https://discourse.vtk.org/t/vtkclippolydata-incorrectly-work/13046)

<div class="topic-metadata">

**Author:** [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)\
**Replies:** 4\
**Last updated:** [January 13, 2024, 3:56am UTC](https://discourse.vtk.org/t/vtkclippolydata-incorrectly-work/13046 "2024-01-13T03:56:58Z")

</div>

I am using vtkClipPolyData to cut a mesh, but it give a incorrect result. The code is: import vtkmodules.all as vtk import numpy as np def CreateActor(ply: vtk.vtkPolyData, color=\[1, 0, 0\]): mapper = vtk.vtkPolyD…

---

## [can VTK work width opengl desktop and qt5 quick?](https://discourse.vtk.org/t/can-vtk-work-width-opengl-desktop-and-qt5-quick/13051)

<div class="topic-metadata">

**Author:** [@nocanstillbb](https://discourse.vtk.org/u/nocanstillbb)\
**Replies:** 5\
**Last updated:** [January 12, 2024, 5:36pm UTC](https://discourse.vtk.org/t/can-vtk-work-width-opengl-desktop-and-qt5-quick/13051 "2024-01-12T17:36:03Z")

</div>

i have opengl 3.0 desktop + qml program like this :Scene Graph - Rendering FBOs in a thread | Qt Quick 5.15.16 I use it play video ,it was work well. when i set vtk graphicsBackend QQuickVTKRenderWindow::setupGra…

---

## [polygon selection](https://discourse.vtk.org/t/polygon-selection/12162)

<div class="topic-metadata">

**Author:** [@claude](https://discourse.vtk.org/u/claude)\
**Replies:** 13\
**Last updated:** [January 12, 2024, 4:30pm UTC](https://discourse.vtk.org/t/polygon-selection/12162 "2024-01-12T16:30:42Z")

</div>

Hi guys, I follow this(https://gitlab.kitware.com/vtk/vtk/-/blob/master/Rendering/Core/Testing/Cxx/TestPolygonSelection.cxx#L122) to select a polygonal area, but the data I get is incomplete and some cells are missing(T…

---

## [Issue with vtkClipClosedSurface on a bone stl file](https://discourse.vtk.org/t/issue-with-vtkclipclosedsurface-on-a-bone-stl-file/1117)

<div class="topic-metadata">

**Author:** [@Amelie](https://discourse.vtk.org/u/Amelie)\
**Replies:** 7\
**Last updated:** [January 12, 2024, 1:53am UTC](https://discourse.vtk.org/t/issue-with-vtkclipclosedsurface-on-a-bone-stl-file/1117 "2024-01-12T01:53:42Z")

</div>

Hey everyone, I’m quite new in using vtk, but I manage to write some code in C++ that allows a user to cut a bone thanks to mouse click. I’ll explain: user select three points on the STL file he wants to cut, a plane i…

---

## [Issue using the vtkFinitePlaneWidget](https://discourse.vtk.org/t/issue-using-the-vtkfiniteplanewidget/13012)

<div class="topic-metadata">

**Author:** [@MarKara](https://discourse.vtk.org/u/MarKara)\
**Replies:** 4\
**Last updated:** [January 12, 2024, 1:17am UTC](https://discourse.vtk.org/t/issue-using-the-vtkfiniteplanewidget/13012 "2024-01-12T01:17:23Z")

</div>

Hi I was hoping to use vtkFinitePlaneWidget in my application but getting the error below. I think I found what is the issue but not sure how to solve it. To display mouse coordinates in my application, I’m tracking t…

---

## [Linker error](https://discourse.vtk.org/t/linker-error/12443)

<div class="topic-metadata">

**Author:** [@toddy](https://discourse.vtk.org/u/toddy)\
**Replies:** 12\
**Last updated:** [January 11, 2024, 3:16pm UTC](https://discourse.vtk.org/t/linker-error/12443 "2024-01-11T15:16:52Z")

</div>

Well I’m stumped. Where are the dependencies for the Java projects specfied in CMake?

---

## [How to solve encoding problems on non-utf8 encoded systems](https://discourse.vtk.org/t/how-to-solve-encoding-problems-on-non-utf8-encoded-systems/13034)

<div class="topic-metadata">

**Author:** [@realwhzc](https://discourse.vtk.org/u/realwhzc)\
**Replies:** 6\
**Last updated:** [January 11, 2024, 12:47pm UTC](https://discourse.vtk.org/t/how-to-solve-encoding-problems-on-non-utf8-encoded-systems/13034 "2024-01-11T12:47:28Z")

</div>

Make SystemTools::FileExists support more languages (#19215) · Issues · VTK / VTK · GitLab (kitware.com) I submitted an issue last week, and then I learned that when reading a file kwsys determines the file’s existence.k…

---

## [Double Click Events are not registered by Observer?](https://discourse.vtk.org/t/double-click-events-are-not-registered-by-observer/13054)

<div class="topic-metadata">

**Author:** [@abrahamezzeddine](https://discourse.vtk.org/u/abrahamezzeddine)\
**Replies:** 0\
**Last updated:** [January 11, 2024, 9:09am UTC](https://discourse.vtk.org/t/double-click-events-are-not-registered-by-observer/13054 "2024-01-11T09:09:27Z")

</div>

Currently trying to perform an annotation procedure with my mouse. Basically, in my custom annotation mode, rotation of the world is disabled so I can perform custom annotations with the mouse (as of now, only record the…

---

## [Abouts setting up two levels renderer, the top level is truncated](https://discourse.vtk.org/t/abouts-setting-up-two-levels-renderer-the-top-level-is-truncated/13015)

<div class="topic-metadata">

**Author:** [@nanoahSR](https://discourse.vtk.org/u/nanoahSR)\
**Replies:** 1\
**Last updated:** [January 11, 2024, 6:04am UTC](https://discourse.vtk.org/t/abouts-setting-up-two-levels-renderer-the-top-level-is-truncated/13015 "2024-01-11T06:04:57Z")

</div>

Hello! I set two layers of render, the first layer shows the larger actor, the second layer shows the smaller actor, to achieve the effect of the small actor on top of the large actor, but after the camera is rotated, t…

---

## [I can see jaggy edges when object is translucent](https://discourse.vtk.org/t/i-can-see-jaggy-edges-when-object-is-translucent/13048)

<div class="topic-metadata">

**Author:** [@baker-Xie](https://discourse.vtk.org/u/baker-Xie)\
**Replies:** 0\
**Last updated:** [January 11, 2024, 1:37am UTC](https://discourse.vtk.org/t/i-can-see-jaggy-edges-when-object-is-translucent/13048 "2024-01-11T01:37:45Z")

</div>

The left is a vtkCubeSource → vtkActor -\>SetOpacity(0.3); The right is a vtkCubeSource → vtkActor -\>SetOpacity(1); I can see clearly jaggy edges in the left cube. Why so much difference? Is there a solution to elimi…

---

## [vtkGeoProjection/vtkGeoTransform differences between VTK 8 and VTK 9](https://discourse.vtk.org/t/vtkgeoprojection-vtkgeotransform-differences-between-vtk-8-and-vtk-9/13010)

<div class="topic-metadata">

**Author:** [@biagas](https://discourse.vtk.org/u/biagas)\
**Replies:** 3\
**Last updated:** [January 10, 2024, 7:25pm UTC](https://discourse.vtk.org/t/vtkgeoprojection-vtkgeotransform-differences-between-vtk-8-and-vtk-9/13010 "2024-01-10T19:25:18Z")

</div>

I have a simple test that opens a vtk file and performs a vtkGeoTransform and writes the results. The results between the two VTK versions are vastly different. I tried understanding what may have changed (besides the …

---

## [VTK vs ITK metadata (size, origin, spacing, direction)](https://discourse.vtk.org/t/vtk-vs-itk-metadata-size-origin-spacing-direction/13041)

<div class="topic-metadata">

**Author:** [@CharNamIII](https://discourse.vtk.org/u/CharNamIII)\
**Replies:** 2\
**Last updated:** [January 10, 2024, 2:48pm UTC](https://discourse.vtk.org/t/vtk-vs-itk-metadata-size-origin-spacing-direction/13041 "2024-01-10T14:48:29Z")

</div>

Hi all, I’m trying to convert a polydata and place it in the same space as image X using the code below: def polydata\_to\_imagedata(polydata, direction, dimensions, origin, spacing): dx, dy, dz = dimensions ox,o…

---

## [Minimum ray length during intersection test](https://discourse.vtk.org/t/minimum-ray-length-during-intersection-test/13031)

<div class="topic-metadata">

**Author:** [@ehblackman](https://discourse.vtk.org/u/ehblackman)\
**Replies:** 1\
**Last updated:** [January 9, 2024, 11:50am UTC](https://discourse.vtk.org/t/minimum-ray-length-during-intersection-test/13031 "2024-01-09T11:50:19Z")

</div>

Is there a minimum ray length used in VTK for intersection tests? My script involves generating a point within a 3d convex hull, and firing rays of different lengths from that point in random directions (vtkOBBTree.Inter…

---

## [How to inherit from a vtk class and a QObject](https://discourse.vtk.org/t/how-to-inherit-from-a-vtk-class-and-a-qobject/12973)

<div class="topic-metadata">

**Author:** [@baker-Xie](https://discourse.vtk.org/u/baker-Xie)\
**Replies:** 6\
**Last updated:** [January 9, 2024, 5:02am UTC](https://discourse.vtk.org/t/how-to-inherit-from-a-vtk-class-and-a-qobject/12973 "2024-01-09T05:02:35Z")

</div>

For example, the following code doesn’t work. (cannot compile) class CustomMouseInteractorStyle : public vtkInteractorStyleTrackballCamera, QObject { Q\_Object public: static CustomMouseInteractorStyle\* New(); vtkTyp…

---

## [C++ vtkWindow rendered in juypter/web (trame)](https://discourse.vtk.org/t/c-vtkwindow-rendered-in-juypter-web-trame/13026)

<div class="topic-metadata">

**Author:** [@sboogert](https://discourse.vtk.org/u/sboogert)\
**Replies:** 3\
**Last updated:** [January 9, 2024, 12:01am UTC](https://discourse.vtk.org/t/c-vtkwindow-rendered-in-juypter-web-trame/13026 "2024-01-09T00:01:39Z")

</div>

I have a large C++ application which uses VTK as a visualisation system. I plan to have some minimal binding of my C++ application in Python (using pybind11) allowing users to drive the application from Jupyter. Now it w…

---

## [How to deal with share points among multiple datasets?](https://discourse.vtk.org/t/how-to-deal-with-share-points-among-multiple-datasets/12915)

<div class="topic-metadata">

**Author:** [@rockydut](https://discourse.vtk.org/u/rockydut)\
**Replies:** 10\
**Last updated:** [January 8, 2024, 10:50am UTC](https://discourse.vtk.org/t/how-to-deal-with-share-points-among-multiple-datasets/12915 "2024-01-08T10:50:45Z")

</div>

This is a problem related to sharing nodes among multiple datasets. Suppose there are three datasets: one vtkUnstructuredGrid and two vtkPolyData. The nodes in these three datasets are assigned unified global node numb…

---

## [vtkOBJImporter load data, and how to get the color of point, and change some of the cells' color by SetScalars?](https://discourse.vtk.org/t/vtkobjimporter-load-data-and-how-to-get-the-color-of-point-and-change-some-of-the-cells-color-by-setscalars/12891)

<div class="topic-metadata">

**Author:** [@yangyang117](https://discourse.vtk.org/u/yangyang117)\
**Replies:** 3\
**Last updated:** [January 8, 2024, 9:06am UTC](https://discourse.vtk.org/t/vtkobjimporter-load-data-and-how-to-get-the-color-of-point-and-change-some-of-the-cells-color-by-setscalars/12891 "2024-01-08T09:06:37Z")

</div>

Hi, When I use vtkOBJImporter load some obj mtl file, I can get the mapper, actor, and polydata of the data, But I want to get the color of point in polydata by texture data. Issue1: I found some ways to get the rgb val…

---

## [object seems wrong rendered when transparency are used](https://discourse.vtk.org/t/object-seems-wrong-rendered-when-transparency-are-used/13014)

<div class="topic-metadata">

**Author:** [@baker-Xie](https://discourse.vtk.org/u/baker-Xie)\
**Replies:** 3\
**Last updated:** [January 8, 2024, 4:24am UTC](https://discourse.vtk.org/t/object-seems-wrong-rendered-when-transparency-are-used/13014 "2024-01-08T04:24:10Z")

</div>

I used vtkGlyph3DMapper to create several cubes. I use RGBA to set the color for each cube. When I set (255, 0, 0, 255) for all the cubes, the render result is below When I set different alpha, from 0 to 255, the re…

[Previous page](https://discourse.vtk.org/c/support/6.md?page=31)

[Next page](https://discourse.vtk.org/c/support/6.md?page=33)