# Latest

**URL:** https://discourse.vtk.org/latest.md?page=118

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

**Page:** 119

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## [How to add the 'vn' attribute to the obj file through vtk or other methods](https://discourse.vtk.org/t/how-to-add-the-vn-attribute-to-the-obj-file-through-vtk-or-other-methods/9334)

<div class="topic-metadata">

**Author:** [@Dwight98](https://discourse.vtk.org/u/Dwight98)\
**Replies:** 0\
**Last updated:** [September 13, 2022, 6:07am UTC](https://discourse.vtk.org/t/how-to-add-the-vn-attribute-to-the-obj-file-through-vtk-or-other-methods/9334 "2022-09-13T06:07:23Z")

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I have an obj file that contains only point properties and face properties, I want to generate normal vector properties for the file, how do I do it?

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## [Emscripten: WebGL: INVALID\_ENUM: readPixels: invalid format](https://discourse.vtk.org/t/emscripten-webgl-invalid-enum-readpixels-invalid-format/4565)

<div class="topic-metadata">

**Author:** [@ZigaSajovic](https://discourse.vtk.org/u/ZigaSajovic)\
**Replies:** 7\
**Last updated:** [September 13, 2022, 3:17am UTC](https://discourse.vtk.org/t/emscripten-webgl-invalid-enum-readpixels-invalid-format/4565 "2022-09-13T03:17:20Z")

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When using vtkOpenGLHardwareSelector one gets two errors WebGL: INVALID\_ENUM: readPixels: invalid format and GL\_INVALID\_OPERATION: Invalid format and type combination. The errors arise from the javascript call GLc…

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## [How can i implement reset camera features in volume rendering?](https://discourse.vtk.org/t/how-can-i-implement-reset-camera-features-in-volume-rendering/9290)

<div class="topic-metadata">

**Author:** [@Yuvi-416](https://discourse.vtk.org/u/Yuvi-416)\
**Replies:** 4\
**Last updated:** [September 13, 2022, 2:51am UTC](https://discourse.vtk.org/t/how-can-i-implement-reset-camera-features-in-volume-rendering/9290 "2022-09-13T02:51:04Z")

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Hi all, I am wondering how can I implement reset camera features in my volume render visualizer similar to what I saw in the itk-vtk viewer.

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## [How to actively trigger resolution reduction when zooming in and rotating on a tablet？](https://discourse.vtk.org/t/how-to-actively-trigger-resolution-reduction-when-zooming-in-and-rotating-on-a-tablet/9270)

<div class="topic-metadata">

**Author:** [@zhangzhi93](https://discourse.vtk.org/u/zhangzhi93)\
**Replies:** 3\
**Last updated:** [September 13, 2022, 2:48am UTC](https://discourse.vtk.org/t/how-to-actively-trigger-resolution-reduction-when-zooming-in-and-rotating-on-a-tablet/9270 "2022-09-13T02:48:50Z")

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When the volume image is manipulated on a tablet, the resolution will not be reduced at the beginning, resulting in operations such as zooming and rotating, which will be very laggy. After that, continuous operation will…

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## [How do I eliminate the "ripples" of Volume Rendering?](https://discourse.vtk.org/t/how-do-i-eliminate-the-ripples-of-volume-rendering/4109)

<div class="topic-metadata">

**Author:** [@008](https://discourse.vtk.org/u/008)\
**Replies:** 12\
**Last updated:** [September 12, 2022, 12:49pm UTC](https://discourse.vtk.org/t/how-do-i-eliminate-the-ripples-of-volume-rendering/4109 "2022-09-12T12:49:57Z")

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Hi, I have a series of cross-sectional images of a 3D object composed of two materials (green and purple) with a geometric shape etched on it. I use “volume rendering” to render it, but when I rotate the object, it has …

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## [3D interaction does not work in RenderWindowControl (Activiz)](https://discourse.vtk.org/t/3d-interaction-does-not-work-in-renderwindowcontrol-activiz/9313)

<div class="topic-metadata">

**Author:** [@masoud](https://discourse.vtk.org/u/masoud)\
**Replies:** 2\
**Last updated:** [September 12, 2022, 11:13am UTC](https://discourse.vtk.org/t/3d-interaction-does-not-work-in-renderwindowcontrol-activiz/9313 "2022-09-12T11:13:35Z")

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Hello everyone, I am trying to build a windows form application in C# and show a 3D reconstruction of a dicom series via putting a “RenderWindowControl” in the form. Actually, I could successfully build the reconstructi…

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## [Rendering multiple solids with only one Actor, yet retaining RGBA and Picking](https://discourse.vtk.org/t/rendering-multiple-solids-with-only-one-actor-yet-retaining-rgba-and-picking/7021)

<div class="topic-metadata">

**Author:** [@Olivier](https://discourse.vtk.org/u/Olivier)\
**Replies:** 6\
**Last updated:** [September 12, 2022, 8:28am UTC](https://discourse.vtk.org/t/rendering-multiple-solids-with-only-one-actor-yet-retaining-rgba-and-picking/7021 "2022-09-12T08:28:26Z")

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Hi dear friends, I’ve post an issue where I was facing bad overall framerate with a scene containing 500+ actors. Thanks to many useful answers, I’ve changed my code to create each solid as a vtkPolydata, then merging …

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## [Loosing duplicate points when applying vtkClipPolyData?](https://discourse.vtk.org/t/loosing-duplicate-points-when-applying-vtkclippolydata/9327)

<div class="topic-metadata">

**Author:** [@ugis](https://discourse.vtk.org/u/ugis)\
**Replies:** 4\
**Last updated:** [September 12, 2022, 8:27am UTC](https://discourse.vtk.org/t/loosing-duplicate-points-when-applying-vtkclippolydata/9327 "2022-09-12T08:27:37Z")

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Hi all, I am working on a large visualization project based on VTK and have stumbled on the following issue. What I am doing: Creating many polyData starting with some custom polygons; Assinging scalar values to point…

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## [Is there an InteractorStyle that allows moving across a surface while tethered to it?](https://discourse.vtk.org/t/is-there-an-interactorstyle-that-allows-moving-across-a-surface-while-tethered-to-it/9320)

<div class="topic-metadata">

**Author:** [@llobera](https://discourse.vtk.org/u/llobera)\
**Replies:** 2\
**Last updated:** [September 12, 2022, 7:40am UTC](https://discourse.vtk.org/t/is-there-an-interactorstyle-that-allows-moving-across-a-surface-while-tethered-to-it/9320 "2022-09-12T07:40:27Z")

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Is there any InteractorStyle that allows the viewer to move (using cursor arrow keys) across a surface while maintaining the elevation tethered to that surface? I am thinking here as if you were moving across a terrain f…

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## [vtkCellPicker is not work for a stl file with directory in Chinese](https://discourse.vtk.org/t/vtkcellpicker-is-not-work-for-a-stl-file-with-directory-in-chinese/4437)

<div class="topic-metadata">

**Author:** [@TremblingV5](https://discourse.vtk.org/u/TremblingV5)\
**Replies:** 1\
**Last updated:** [September 11, 2022, 3:55pm UTC](https://discourse.vtk.org/t/vtkcellpicker-is-not-work-for-a-stl-file-with-directory-in-chinese/4437 "2022-09-11T15:55:06Z")

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Hello Everyone! I use vtkSTLReader read a stl file with set filename by gbk(encoding of Chinese)，I found that vtkCellPicker is not work. I can get cell id byuse Pick() ,but i can’t get the position of it. In addition,…

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## [F3D v1.0.0, a fast and minimalist 3D viewer, has been released !](https://discourse.vtk.org/t/f3d-v1-0-0-a-fast-and-minimalist-3d-viewer-has-been-released/3507)

<div class="topic-metadata">

**Author:** [@mwestphal](https://discourse.vtk.org/u/mwestphal)\
**Replies:** 2\
**Last updated:** [September 11, 2022, 6:19am UTC](https://discourse.vtk.org/t/f3d-v1-0-0-a-fast-and-minimalist-3d-viewer-has-been-released/3507 "2022-09-11T06:19:13Z")

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F3D v1.0, a fast and minimalist 3D viewer has been released ! F3D is a VTK-based 3D viewer following the KISS principle, so it is minimalist, efficient, has no GUI, has simple interaction mechanisms and is fully cont…

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## [change blendMode in vtkResliceCursor](https://discourse.vtk.org/t/change-blendmode-in-vtkreslicecursor/9311)

<div class="topic-metadata">

**Author:** [@Alexandera](https://discourse.vtk.org/u/Alexandera)\
**Replies:** 0\
**Last updated:** [September 10, 2022, 4:11am UTC](https://discourse.vtk.org/t/change-blendmode-in-vtkreslicecursor/9311 "2022-09-10T04:11:50Z")

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My environment is Python 3.7.0 and VTK 9.1.0 I am realizing my own MPR application with example. The following is the snapshot on the rendering window. I know the class vtkResliceCursorWidget internally uses vtk vtk…

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## [How can I load Nii files to React Vtk.js Reader?](https://discourse.vtk.org/t/how-can-i-load-nii-files-to-react-vtk-js-reader/9309)

<div class="topic-metadata">

**Author:** [@Bek](https://discourse.vtk.org/u/Bek)\
**Replies:** 2\
**Last updated:** [September 9, 2022, 11:36pm UTC](https://discourse.vtk.org/t/how-can-i-load-nii-files-to-react-vtk-js-reader/9309 "2022-09-09T23:36:13Z")

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I was having troubles loading Nii files into the React Vtk.js Reader. What is the best way to load them. Should I convert the Nii files to vti files? If so how would I do that?

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## [vtkGenericOpenGLRenderWindow::Render() fails - how to use this class properly?](https://discourse.vtk.org/t/vtkgenericopenglrenderwindow-render-fails-how-to-use-this-class-properly/9307)

<div class="topic-metadata">

**Author:** [@Tomasso](https://discourse.vtk.org/u/Tomasso)\
**Replies:** 0\
**Last updated:** [September 9, 2022, 10:15pm UTC](https://discourse.vtk.org/t/vtkgenericopenglrenderwindow-render-fails-how-to-use-this-class-properly/9307 "2022-09-09T22:15:35Z")

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I’m running vtk-9.0.1 on ubuntu 20.04.5. Can someone please refer me to an example that uses vtkGenericOpenGLRenderWindow properly? MyClass has a member called renderWindow\_ wich points to a vtkGenericOpenGLRenderWindo…

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## [Equivalent of const vtkIdType \*& in python?](https://discourse.vtk.org/t/equivalent-of-const-vtkidtype-in-python/9298)

<div class="topic-metadata">

**Author:** [@Unique](https://discourse.vtk.org/u/Unique)\
**Replies:** 3\
**Last updated:** [September 9, 2022, 8:17pm UTC](https://discourse.vtk.org/t/equivalent-of-const-vtkidtype-in-python/9298 "2022-09-09T20:17:50Z")

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I’m trying to use the GetFaceToAdjacentFaces method but I don’t know what argument I need to pass, I’ve read the docs and I should pass a ‘const vtkIdType \*&’ but I don’t know how to do this in python. Code: reader = v…

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## [How to copy zbuffer after window interaction](https://discourse.vtk.org/t/how-to-copy-zbuffer-after-window-interaction/9289)

<div class="topic-metadata">

**Author:** [@llobera](https://discourse.vtk.org/u/llobera)\
**Replies:** 8\
**Last updated:** [September 9, 2022, 8:18am UTC](https://discourse.vtk.org/t/how-to-copy-zbuffer-after-window-interaction/9289 "2022-09-09T08:18:45Z")

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I am trying to figure out how to obtain the zbuffer for a view after I have interacted with it. I am just starting with VTK. Here is the code that I have so far, # Create a render window, and interactor renderWindow = …

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## [Compilation error:../Common/Core/vtkOStreamWrapper.h:108: memory exhausted](https://discourse.vtk.org/t/compilation-error-common-core-vtkostreamwrapper-h-memory-exhausted/9280)

<div class="topic-metadata">

**Author:** [@AlexLuya](https://discourse.vtk.org/u/AlexLuya)\
**Replies:** 7\
**Last updated:** [September 8, 2022, 1:08pm UTC](https://discourse.vtk.org/t/compilation-error-common-core-vtkostreamwrapper-h-memory-exhausted/9280 "2022-09-08T13:08:55Z")

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I got a compilation error: vtkWrapHierarchy-9.1: In /home/user/workspace/VTK/Common/Core/vtkOStreamWrapper.h:108: memory exhausted. make\[2\]: \*\*\* \[Common/Core/CMakeFiles/vtkCommonCore-hierarchy.dir/build.make:281: lib/x…

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## [How to pan/translate/move the actor without changing its coordinates or pan the camera using VTK?](https://discourse.vtk.org/t/how-to-pan-translate-move-the-actor-without-changing-its-coordinates-or-pan-the-camera-using-vtk/9300)

<div class="topic-metadata">

**Author:** [@ZyFan](https://discourse.vtk.org/u/ZyFan)\
**Replies:** 0\
**Last updated:** [September 8, 2022, 8:02pm UTC](https://discourse.vtk.org/t/how-to-pan-translate-move-the-actor-without-changing-its-coordinates-or-pan-the-camera-using-vtk/9300 "2022-09-08T20:02:06Z")

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Hi All, I’m trying to develop a function that can pan the actor in the render window without changing its coordinates(I can not use the transform filter), just like drag the object in the window using your mouse. So I t…

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## [Retrieving shadow values from a terrain](https://discourse.vtk.org/t/retrieving-shadow-values-from-a-terrain/9285)

<div class="topic-metadata">

**Author:** [@llobera](https://discourse.vtk.org/u/llobera)\
**Replies:** 3\
**Last updated:** [September 7, 2022, 3:38pm UTC](https://discourse.vtk.org/t/retrieving-shadow-values-from-a-terrain/9285 "2022-09-07T15:38:16Z")

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I have a regular gridded heightmap (terrain) that I converted into a VtkPolyData using VtkDelaunay2D. When rendering it, I set a light source at a particular location. Is there a way to retrieve the values for the shado…

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## [How to disable normal vector selection handle in vtkPlaneWidget](https://discourse.vtk.org/t/how-to-disable-normal-vector-selection-handle-in-vtkplanewidget/9288)

<div class="topic-metadata">

**Author:** [@Jishnu](https://discourse.vtk.org/u/Jishnu)\
**Replies:** 0\
**Last updated:** [September 7, 2022, 4:47am UTC](https://discourse.vtk.org/t/how-to-disable-normal-vector-selection-handle-in-vtkplanewidget/9288 "2022-09-07T04:47:09Z")

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Hello, I want to disable the vector selection handle in vtkPlaneWidget. However, I want to keep the sphere handles at the corner of the widget. I cannot find any function to specifically set properties for the normal vec…

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## [A Multi Volume Problem of VTK9.2](https://discourse.vtk.org/t/a-multi-volume-problem-of-vtk9-2/9287)

<div class="topic-metadata">

**Author:** [@YRFPC03](https://discourse.vtk.org/u/YRFPC03)\
**Replies:** 1\
**Last updated:** [September 6, 2022, 1:40pm UTC](https://discourse.vtk.org/t/a-multi-volume-problem-of-vtk9-2/9287 "2022-09-06T13:40:48Z")

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When I use multi volume to render multi-body data, the rendering result I get becomes very dim, which is not the case when I render single body data. I have used vtk9，i don’t change the ColorTransferFunction and else be…

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## [Overwrite (or delete) interactor event button press](https://discourse.vtk.org/t/overwrite-or-delete-interactor-event-button-press/9272)

<div class="topic-metadata">

**Author:** [@zaidb](https://discourse.vtk.org/u/zaidb)\
**Replies:** 8\
**Last updated:** [September 6, 2022, 12:35pm UTC](https://discourse.vtk.org/t/overwrite-or-delete-interactor-event-button-press/9272 "2022-09-06T12:35:55Z")

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Hi, I am using vtkRenderWindowInteractor as an interactor with a onMiddleButtonPress defined at runtime. I’m trying to implement a feature that overwrites at one point the existing onMiddleButtonPress callback with a ne…

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## [How to combine vtkImageData?](https://discourse.vtk.org/t/how-to-combine-vtkimagedata/8947)

<div class="topic-metadata">

**Author:** [@Seun](https://discourse.vtk.org/u/Seun)\
**Replies:** 18\
**Last updated:** [September 6, 2022, 12:20pm UTC](https://discourse.vtk.org/t/how-to-combine-vtkimagedata/8947 "2022-09-06T12:20:28Z")

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Hello everyone, I'm wondering if someone could help with an issue I'm trying to address. I have a situation where I would like to combine at least 2 vtkImageDatas (A & B) that could possibly have the following characte…

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## [vtkAnnotatedCubeActor transformation question](https://discourse.vtk.org/t/vtkannotatedcubeactor-transformation-question/9271)

<div class="topic-metadata">

**Author:** [@a772485252](https://discourse.vtk.org/u/a772485252)\
**Replies:** 8\
**Last updated:** [September 6, 2022, 1:11am UTC](https://discourse.vtk.org/t/vtkannotatedcubeactor-transformation-question/9271 "2022-09-06T01:11:29Z")

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Rotation of vtkonnotatedcubeactor does not work.Is there a mistake in my usage？I put it in vtkorientationmarkerwidget and call its rotation method.

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## [vtkClipDataSet returns many smaller subpart types](https://discourse.vtk.org/t/vtkclipdataset-returns-many-smaller-subpart-types/9264)

<div class="topic-metadata">

**Author:** [@Spacetracker](https://discourse.vtk.org/u/Spacetracker)\
**Replies:** 1\
**Last updated:** [September 5, 2022, 1:45pm UTC](https://discourse.vtk.org/t/vtkclipdataset-returns-many-smaller-subpart-types/9264 "2022-09-05T13:45:48Z")

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Why does the vtkClipDataSet break up the original vtkHexahedron types from the vtkStructuredGrid into many smaller subpart types in the resulting vtkUnstructuredGrid? I expected the hexahedron cell types to be retained …

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## [How to avoid or repair non-manifold edge when using vtkClipDataSet?](https://discourse.vtk.org/t/how-to-avoid-or-repair-non-manifold-edge-when-using-vtkclipdataset/9279)

<div class="topic-metadata">

**Author:** [@altair0985](https://discourse.vtk.org/u/altair0985)\
**Replies:** 0\
**Last updated:** [September 5, 2022, 8:57am UTC](https://discourse.vtk.org/t/how-to-avoid-or-repair-non-manifold-edge-when-using-vtkclipdataset/9279 "2022-09-05T08:57:39Z")

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I am using vtkClipDataSet to clip unstructured grid composed of vtkPolyhedron. The first time of clipping is always perfect, but the second time or more sometimes generate warning such as non-manifold edge. How to avoid …

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## [How to use ProgrammableGlyphFilter?](https://discourse.vtk.org/t/how-to-use-programmableglyphfilter/9274)

<div class="topic-metadata">

**Author:** [@tmnku](https://discourse.vtk.org/u/tmnku)\
**Replies:** 1\
**Last updated:** [September 5, 2022, 6:14am UTC](https://discourse.vtk.org/t/how-to-use-programmableglyphfilter/9274 "2022-09-05T06:14:41Z")

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Hi, I’m trying to create glyphs which each have a unique color, transformation and cellIDs so I can pick them individually. I found this post which suggested a ProgrammableGlyphFilter and I managed to get the picker to …

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## [vtkAVIWriter not available on python wheel](https://discourse.vtk.org/t/vtkaviwriter-not-available-on-python-wheel/9162)

<div class="topic-metadata">

**Author:** [@Flagada](https://discourse.vtk.org/u/Flagada)\
**Replies:** 3\
**Last updated:** [September 2, 2022, 7:10pm UTC](https://discourse.vtk.org/t/vtkaviwriter-not-available-on-python-wheel/9162 "2022-09-02T19:10:14Z")

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Hi all, Since vtk 9.1 it seems that vtkAVIWriter is no more included in python package for windows. I have the error : module ‘vtkmodules.all’ has no attribute ‘vtkAVIWriter’ This is the same with the latest 9.2 distr…

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## [How to render multiple volumes with correct z-order?](https://discourse.vtk.org/t/how-to-render-multiple-volumes-with-correct-z-order/9253)

<div class="topic-metadata">

**Author:** [@Shuning\_Jiang](https://discourse.vtk.org/u/Shuning_Jiang)\
**Replies:** 5\
**Last updated:** [September 1, 2022, 7:37pm UTC](https://discourse.vtk.org/t/how-to-render-multiple-volumes-with-correct-z-order/9253 "2022-09-01T19:37:13Z")

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Hello everyone, I’m new to VTK and I have a very basic problem but I can’t find a way to solve it. I’m trying to display two volumes that have no overlap by adding two vtkVolume into one renderer. However, the volume th…

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## [Rendering Multiple Volumes](https://discourse.vtk.org/t/rendering-multiple-volumes/9265)

<div class="topic-metadata">

**Author:** [@Kalsyc](https://discourse.vtk.org/u/Kalsyc)\
**Replies:** 4\
**Last updated:** [September 1, 2022, 2:02pm UTC](https://discourse.vtk.org/t/rendering-multiple-volumes/9265 "2022-09-01T14:02:59Z")

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Hi, I have a question. So here I am rendering 3 volumes together (different volume objects and mapper, but same renderer/renderwindow). I notice that at one angle, the volumes are not sorted properly. For this image …

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