# Latest

**URL:** https://discourse.vtk.org/latest.md?page=193

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

**Page:** 194

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## [can VTK get COM and Inertia of object?](https://discourse.vtk.org/t/can-vtk-get-com-and-inertia-of-object/4628)

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**Author:** [@azk](https://discourse.vtk.org/u/azk)\
**Replies:** 5\
**Last updated:** [November 12, 2020, 12:34pm UTC](https://discourse.vtk.org/t/can-vtk-get-com-and-inertia-of-object/4628 "2020-11-12T12:34:35Z")

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Hello, Is there a way to get the properties of an object using Python? Like the Center Of Mass and Inertia Matrix? I tried to find but I could only find this which is in C++ and not in Python. I am not that familiar wi…

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## [Incorrect visualization crossing objects (python, windows, vtk9.0.1)](https://discourse.vtk.org/t/incorrect-visualization-crossing-objects-python-windows-vtk9-0-1/4543)

<div class="topic-metadata">

**Author:** [@l1va](https://discourse.vtk.org/u/l1va)\
**Replies:** 5\
**Last updated:** [November 12, 2020, 8:08am UTC](https://discourse.vtk.org/t/incorrect-visualization-crossing-objects-python-windows-vtk9-0-1/4543 "2020-11-12T08:08:40Z")

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Good day! I built exe for the windows using cx\_Freeze, python3.8, pyQt5, vtk9.0.1 and see that visualization is not correct. It works correctly for the previous (it might be vtk8.1) version. Cut by plane part of the obj…

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## [Confusion about the use of vtkMapper](https://discourse.vtk.org/t/confusion-about-the-use-of-vtkmapper/4640)

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**Author:** [@Jone7](https://discourse.vtk.org/u/Jone7)\
**Replies:** 0\
**Last updated:** [November 12, 2020, 7:21am UTC](https://discourse.vtk.org/t/confusion-about-the-use-of-vtkmapper/4640 "2020-11-12T07:21:32Z")

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I first calculated using vtkTriangleMeshPointNormals Vertex normal, it’s like for the Vertex shader normalMC transmit a value, then I use the vtkPolyDataTangents calculating tangent, when I try to input it, the normal v…

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## [Staggered grid with VTK](https://discourse.vtk.org/t/staggered-grid-with-vtk/4639)

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**Author:** [@GR4EM](https://discourse.vtk.org/u/GR4EM)\
**Replies:** 0\
**Last updated:** [November 12, 2020, 7:18am UTC](https://discourse.vtk.org/t/staggered-grid-with-vtk/4639 "2020-11-12T07:18:34Z")

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Hi all! Is there any way to display results of CFD algorithm that uses staggered grid without interpolation? My main grid is (x\_i,y\_j,z\_k). Pressure is located in the middle of the cell: (x\_i+1/2, y\_j+1/2, z\_k+1/2) and…

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## [Could VTK be used to re-construct colorful 3D using colorful CT images?](https://discourse.vtk.org/t/could-vtk-be-used-to-re-construct-colorful-3d-using-colorful-ct-images/4605)

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**Author:** [@ardeal](https://discourse.vtk.org/u/ardeal)\
**Replies:** 13\
**Last updated:** [November 11, 2020, 3:06pm UTC](https://discourse.vtk.org/t/could-vtk-be-used-to-re-construct-colorful-3d-using-colorful-ct-images/4605 "2020-11-11T15:06:50Z")

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Hi, There are 300 colorful CT slice images. Could I use VTK to re-construct colorful 3D using those colorful CT images? Is there any example code for my reference? Thanks and Best Regards, Ardeal

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## [How to get the coordinates and properties of each vertex in VTK](https://discourse.vtk.org/t/how-to-get-the-coordinates-and-properties-of-each-vertex-in-vtk/4629)

<div class="topic-metadata">

**Author:** [@Jone7](https://discourse.vtk.org/u/Jone7)\
**Replies:** 1\
**Last updated:** [November 11, 2020, 2:37pm UTC](https://discourse.vtk.org/t/how-to-get-the-coordinates-and-properties-of-each-vertex-in-vtk/4629 "2020-11-11T14:37:17Z")

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Forgive me for asking so many questions recently. I want to traverse each vertex, and set the color value for each vertex, and the coordinates of this process I will use its normal, I have its normals are calculated by …

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## [SetRepresentationToWireframe problem....](https://discourse.vtk.org/t/setrepresentationtowireframe-problem/4620)

<div class="topic-metadata">

**Author:** [@DL\_men](https://discourse.vtk.org/u/DL_men)\
**Replies:** 2\
**Last updated:** [November 11, 2020, 1:24pm UTC](https://discourse.vtk.org/t/setrepresentationtowireframe-problem/4620 "2020-11-11T13:24:33Z")

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I use SetRepresentationToWireframe as follow: The frame looks like corrode as shown.How to deal with it? self.original\_mapper.SetInputConnection(self.original\_model.GetOutputPort()) self.orig…

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## [Does libvtkCommon.a libvtkIO.a exist in version from 7.1 to 9.x on linux?](https://discourse.vtk.org/t/does-libvtkcommon-a-libvtkio-a-exist-in-version-from-7-1-to-9-x-on-linux/4626)

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**Author:** [@caikk](https://discourse.vtk.org/u/caikk)\
**Replies:** 0\
**Last updated:** [November 11, 2020, 10:26am UTC](https://discourse.vtk.org/t/does-libvtkcommon-a-libvtkio-a-exist-in-version-from-7-1-to-9-x-on-linux/4626 "2020-11-11T10:26:36Z")

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I am a new user of VTK. When I installed a vtk from source code, both libvtkCommon.a and libvtkIO.a did not exist even using ccmake with a option “BUILD\_SHARED\_LIBS OFF”. There are lots of static lib files with name libv…

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## [Extract color information per vertex](https://discourse.vtk.org/t/extract-color-information-per-vertex/940)

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**Author:** [@bingjian](https://discourse.vtk.org/u/bingjian)\
**Replies:** 1\
**Last updated:** [November 11, 2020, 11:13am UTC](https://discourse.vtk.org/t/extract-color-information-per-vertex/940 "2020-11-11T11:13:12Z")

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I have a quick question about reading the color information stored in a ply file. The following code extracts the xyz coordinate of a given vertex, but how to read the RGB value associated to each vertex? vtkSmartPoint…

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## [points not showing after aplying rotation/translation](https://discourse.vtk.org/t/points-not-showing-after-aplying-rotation-translation/4621)

<div class="topic-metadata">

**Author:** [@azk](https://discourse.vtk.org/u/azk)\
**Replies:** 13\
**Last updated:** [November 11, 2020, 2:41am UTC](https://discourse.vtk.org/t/points-not-showing-after-aplying-rotation-translation/4621 "2020-11-11T02:41:07Z")

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Hello! I am trying to rotate some points in space, but when I try plotting them, they do not show. I am not sure why as I put markers in my code before and after the displaying line and it looks like the program execute…

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## [Rendering 9.6 million tetrahedrons for visualization of a volumetric domain in 3D using python](https://discourse.vtk.org/t/rendering-9-6-million-tetrahedrons-for-visualization-of-a-volumetric-domain-in-3d-using-python/4624)

<div class="topic-metadata">

**Author:** [@rohanamare](https://discourse.vtk.org/u/rohanamare)\
**Replies:** 1\
**Last updated:** [November 11, 2020, 1:30am UTC](https://discourse.vtk.org/t/rendering-9-6-million-tetrahedrons-for-visualization-of-a-volumetric-domain-in-3d-using-python/4624 "2020-11-11T01:30:41Z")

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I am writing a code to render the surface of an entire human body’s mesh. There are nearly 9.6 million tetrahedrons on the surface of this mesh. Even though the code is parallelized to run, it takes a huge amount of time…

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## [Using PickList with vtkHardwareSelector](https://discourse.vtk.org/t/using-picklist-with-vtkhardwareselector/4622)

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**Author:** [@ZigaSajovic](https://discourse.vtk.org/u/ZigaSajovic)\
**Replies:** 0\
**Last updated:** [November 10, 2020, 5:05pm UTC](https://discourse.vtk.org/t/using-picklist-with-vtkhardwareselector/4622 "2020-11-10T17:05:33Z")

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When picking an actor with a vtkRenderer one can use a list of props to choose from renderer-\>PickPropFrom(x, y, propCollection); But when one uses vtkHardwareSelector for manual implementations, this option seems to b…

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## [rotate actor about line](https://discourse.vtk.org/t/rotate-actor-about-line/4594)

<div class="topic-metadata">

**Author:** [@azk](https://discourse.vtk.org/u/azk)\
**Replies:** 7\
**Last updated:** [November 10, 2020, 1:37pm UTC](https://discourse.vtk.org/t/rotate-actor-about-line/4594 "2020-11-10T13:37:10Z")

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Hello! I am new to python and VTK so please have patience :slight\_smile: I have an actor and I would like to rotate it about a line I drew using vtkLineSource(). I chose my start and end points and I drew the line. Now …

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## [python vtk volume rendering dicom images](https://discourse.vtk.org/t/python-vtk-volume-rendering-dicom-images/4602)

<div class="topic-metadata">

**Author:** [@Charalambos\_Greg](https://discourse.vtk.org/u/Charalambos_Greg)\
**Replies:** 2\
**Last updated:** [November 10, 2020, 10:00am UTC](https://discourse.vtk.org/t/python-vtk-volume-rendering-dicom-images/4602 "2020-11-10T10:00:47Z")

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I try to write a python code with vtk to volume render dicom images but as i get no error in my code the window is only back can anyone pls give some guidelines on what to do? I am new with vtk!! My code: import vtk p…

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## [Help to Build project under WIn 10](https://discourse.vtk.org/t/help-to-build-project-under-win-10/4585)

<div class="topic-metadata">

**Author:** [@cean\_wang](https://discourse.vtk.org/u/cean_wang)\
**Replies:** 9\
**Last updated:** [November 10, 2020, 3:34am UTC](https://discourse.vtk.org/t/help-to-build-project-under-win-10/4585 "2020-11-10T03:34:30Z")

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Hi, I am on win10 + VS2017 + VTK9.0.1. following this demo: https://lorensen.github.io/VTKExamples/site/Cxx/IO/ReadAllUnstructuredGridTypes/ At the end, at Building the project: make command gives this message: make:…

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## [Two questions about new module system](https://discourse.vtk.org/t/two-questions-about-new-module-system/2864)

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**Author:** [@estan](https://discourse.vtk.org/u/estan)\
**Replies:** 23\
**Last updated:** [November 10, 2020, 3:06am UTC](https://discourse.vtk.org/t/two-questions-about-new-module-system/2864 "2020-11-10T03:06:37Z")

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Hi all, Having a first look at porting our application to VTK 9.0.0. First question is about vtkRenderingContextOpenGL2. With 9.0.0 it seems we no longer get that library? What should I link against to pick the OpenGL2…

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## [vtkPlanes not making planes](https://discourse.vtk.org/t/vtkplanes-not-making-planes/4611)

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**Author:** [@Gilthalas](https://discourse.vtk.org/u/Gilthalas)\
**Replies:** 2\
**Last updated:** [November 9, 2020, 7:44pm UTC](https://discourse.vtk.org/t/vtkplanes-not-making-planes/4611 "2020-11-09T19:44:55Z")

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I’m attempting to make a vtkPlanes object with the following Java code: vtkPlanes planes = new vtkPlanes(); planes.SetPoints(planePoints); planes.SetNormals(planeNormals); Where planePoints is a vtkPoints object and pl…

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## [How to get a tangent vector for a vertex in VTK9.0?](https://discourse.vtk.org/t/how-to-get-a-tangent-vector-for-a-vertex-in-vtk9-0/4600)

<div class="topic-metadata">

**Author:** [@Jone7](https://discourse.vtk.org/u/Jone7)\
**Replies:** 1\
**Last updated:** [November 9, 2020, 10:39am UTC](https://discourse.vtk.org/t/how-to-get-a-tangent-vector-for-a-vertex-in-vtk9-0/4600 "2020-11-09T10:39:41Z")

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Hi, I want to use a MERL material on a polydata, but I’m confused about how to get a tangent vector for a vertex in vertex shader. Thanks!

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## [Update of vtkExtractVOI slow in sagittal direction](https://discourse.vtk.org/t/update-of-vtkextractvoi-slow-in-sagittal-direction/4583)

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**Author:** [@Keyn](https://discourse.vtk.org/u/Keyn)\
**Replies:** 8\
**Last updated:** [November 9, 2020, 8:33am UTC](https://discourse.vtk.org/t/update-of-vtkextractvoi-slow-in-sagittal-direction/4583 "2020-11-09T08:33:25Z")

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Hello everyone! I am developing a DICOM viewer/segmentation software in C++, using vtk and vtk-dicom to load the images and OpenCV to process them within an Qt GUI. For the initial loading process, I let a vtkDICOMDire…

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## [builing on OSX XCode 12.0](https://discourse.vtk.org/t/builing-on-osx-xcode-12-0/4286)

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**Author:** [@djduke](https://discourse.vtk.org/u/djduke)\
**Replies:** 5\
**Last updated:** [October 19, 2020, 12:56pm UTC](https://discourse.vtk.org/t/builing-on-osx-xcode-12-0/4286 "2020-10-19T12:56:20Z")

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I’ve recently bumped my OSX to 10.15.6 (Catalina) with XCode 12.0 and have run into issues rebuilding VTK from a fresh git checkout. I have Python3 installed via MacPorts The build goes fine. However when I try to run …

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## [Are the coordinate systems of sphere and polyline different?](https://discourse.vtk.org/t/are-the-coordinate-systems-of-sphere-and-polyline-different/4548)

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**Author:** [@clolent](https://discourse.vtk.org/u/clolent)\
**Replies:** 14\
**Last updated:** [November 9, 2020, 6:21am UTC](https://discourse.vtk.org/t/are-the-coordinate-systems-of-sphere-and-polyline-different/4548 "2020-11-09T06:21:55Z")

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Hello, I’m a user who just started using VTK. A problem occurred while trying to create a line and connect it to the center of the sphere. Here’s what happened: poly line RED ( 0,0,-50 ) ~ ( 5,0,-50 ) BLUE ( 0,0,-5…

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## [VTK static library throws LNK error in VS2019](https://discourse.vtk.org/t/vtk-static-library-throws-lnk-error-in-vs2019/4599)

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**Author:** [@DFlyer](https://discourse.vtk.org/u/DFlyer)\
**Replies:** 7\
**Last updated:** [November 7, 2020, 3:21pm UTC](https://discourse.vtk.org/t/vtk-static-library-throws-lnk-error-in-vs2019/4599 "2020-11-07T15:21:46Z")

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OS : Windows 10 VTK version : VTK 9.0.1 Configuration : X64 Debug Platform: VS2019 (v142) I built VTK static libs with cmake flag BUILD\_SHARED\_LIBS = 0 When I use them in Visual Studio, I see lot of link error, i susp…

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## [Running VTK on a system with OpenGL version 1.1 or less](https://discourse.vtk.org/t/running-vtk-on-a-system-with-opengl-version-1-1-or-less/3260)

<div class="topic-metadata">

**Author:** [@Velchivz](https://discourse.vtk.org/u/Velchivz)\
**Replies:** 6\
**Last updated:** [November 6, 2020, 4:51pm UTC](https://discourse.vtk.org/t/running-vtk-on-a-system-with-opengl-version-1-1-or-less/3260 "2020-11-06T16:51:21Z")

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Hello, I first posted about this issue in Stack Overflow: I am working on a project that uses QT and VTK. It works in several machines without any problems (including Mac OS). I tried to run it on a Surface Pro X and …

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## [VTK 9: Outdated examples included in source code archive?](https://discourse.vtk.org/t/vtk-9-outdated-examples-included-in-source-code-archive/4580)

<div class="topic-metadata">

**Author:** [@codeling](https://discourse.vtk.org/u/codeling)\
**Replies:** 0\
**Last updated:** [November 5, 2020, 3:36pm UTC](https://discourse.vtk.org/t/vtk-9-outdated-examples-included-in-source-code-archive/4580 "2020-11-05T15:36:51Z")

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We just tried to build some of the “Tutorial” examples included in VTK 9.0.(0/1) source .tar.gz from vtk.org, and they don’t seem to work - (CMake reports Unknown CMake command "vtk\_module\_config"). On closer inspection…

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## [How to make the point from bspline include the control point?](https://discourse.vtk.org/t/how-to-make-the-point-from-bspline-include-the-control-point/4577)

<div class="topic-metadata">

**Author:** [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)\
**Replies:** 0\
**Last updated:** [November 5, 2020, 2:32pm UTC](https://discourse.vtk.org/t/how-to-make-the-point-from-bspline-include-the-control-point/4577 "2020-11-05T14:32:34Z")

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For example, I have 7 control point, then I use the bspline to generate the smooth line. However, I find the generated smooth points may not include the control point. The code is: spParametricSpline = vtk.vtkParame…

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## [vtkImageReslice is very slow](https://discourse.vtk.org/t/vtkimagereslice-is-very-slow/4570)

<div class="topic-metadata">

**Author:** [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)\
**Replies:** 7\
**Last updated:** [November 5, 2020, 2:29pm UTC](https://discourse.vtk.org/t/vtkimagereslice-is-very-slow/4570 "2020-11-05T14:29:04Z")

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I use vtkImageReslice to get a resliced image, and the code (python) is: reslice = vtk.vtkImageReslice() reslice.SetInputData(image) reslice.SetOutputDimensionality(2) reslice.SetAutoCrop…

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## [How to detect if the mouse is over an actor?](https://discourse.vtk.org/t/how-to-detect-if-the-mouse-is-over-an-actor/4572)

<div class="topic-metadata">

**Author:** [@learn\_forever](https://discourse.vtk.org/u/learn_forever)\
**Replies:** 1\
**Last updated:** [November 5, 2020, 12:32pm UTC](https://discourse.vtk.org/t/how-to-detect-if-the-mouse-is-over-an-actor/4572 "2020-11-05T12:32:01Z")

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I can do this by checking if the actor can be picked during mouse moving. But I don’t think this is an efficient way. So, can any VTK experts give me some suggestions? Thanks a lot.

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## [How to Draw on the vtkImageViewer2?](https://discourse.vtk.org/t/how-to-draw-on-the-vtkimageviewer2/4529)

<div class="topic-metadata">

**Author:** [@wulicheng](https://discourse.vtk.org/u/wulicheng)\
**Replies:** 3\
**Last updated:** [November 5, 2020, 11:03am UTC](https://discourse.vtk.org/t/how-to-draw-on-the-vtkimageviewer2/4529 "2020-11-05T11:03:18Z")

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I want to draw a polyon on the vtkImageViewer2 and colored it ?

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## [How to Get points coords with actor](https://discourse.vtk.org/t/how-to-get-points-coords-with-actor/4574)

<div class="topic-metadata">

**Author:** [@DL\_men](https://discourse.vtk.org/u/DL_men)\
**Replies:** 0\
**Last updated:** [November 5, 2020, 3:08am UTC](https://discourse.vtk.org/t/how-to-get-points-coords-with-actor/4574 "2020-11-05T03:08:59Z")

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I have a dataset, points and cells are origin from this dataset. Not all dataset poins are used, How can i get coords of all used points on prob(actor) directly? just like paraview 5.8.0 function: selecte points on c…

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## [UnsatisfiedLinkError in commandline not in eclipse](https://discourse.vtk.org/t/unsatisfiedlinkerror-in-commandline-not-in-eclipse/4555)

<div class="topic-metadata">

**Author:** [@Daniel](https://discourse.vtk.org/u/Daniel)\
**Replies:** 3\
**Last updated:** [November 4, 2020, 8:52pm UTC](https://discourse.vtk.org/t/unsatisfiedlinkerror-in-commandline-not-in-eclipse/4555 "2020-11-04T20:52:52Z")

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Hi there, I am testing the example “ReleaseVtkPanel.java” by Sebastien Jourdain. It works as desired under eclipse and also as an exported jar-file, if you start it with a double click. But if I start the jar from the …

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