# Latest

**URL:** https://discourse.vtk.org/latest.md?page=151

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

**Page:** 152

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## [Create LODs with vtkExtractHierarchicalBins](https://discourse.vtk.org/t/create-lods-with-vtkextracthierarchicalbins/7377)

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**Author:** [@Julienchz](https://discourse.vtk.org/u/Julienchz)\
**Replies:** 0\
**Last updated:** [December 9, 2021, 2:10pm UTC](https://discourse.vtk.org/t/create-lods-with-vtkextracthierarchicalbins/7377 "2021-12-09T14:10:56Z")

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Hi :slightly\_smiling\_face: I have a pointcloud in a vtkPoints. I am trying to create LODs of my pointcloud with vtkHierarchicalBinningFilter and vtkExtractHierarchicalBins but when I rendered different levels or bins I…

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## [vtkmdiview file](https://discourse.vtk.org/t/vtkmdiview-file/7376)

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**Author:** [@Taimour](https://discourse.vtk.org/u/Taimour)\
**Replies:** 0\
**Last updated:** [December 9, 2021, 1:23pm UTC](https://discourse.vtk.org/t/vtkmdiview-file/7376 "2021-12-09T13:23:59Z")

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Hi everyone! I am working on a project that has a files named as vtkMDIView.h and vtkMDIView.cpp. In file desciption, it is written : Program: Visualization Toolkit Module: RCSfile: vtkMDIView.cpp,v Language: …

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## [vtkVoxelGrid color problem](https://discourse.vtk.org/t/vtkvoxelgrid-color-problem/7371)

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**Author:** [@Julienchz](https://discourse.vtk.org/u/Julienchz)\
**Replies:** 1\
**Last updated:** [December 9, 2021, 9:31am UTC](https://discourse.vtk.org/t/vtkvoxelgrid-color-problem/7371 "2021-12-09T09:31:35Z")

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Hello, I have a pointcloud that I want to downsample with a vtkVoxelGrid. The problem is when I dowmsampled my vtkPoints, I loose point’s color, how can I solve this problem ? vtkNew\<vtkVertexGlyphFilter\> m\_glyphFilterp…

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## [Clipping data only on area selected](https://discourse.vtk.org/t/clipping-data-only-on-area-selected/7375)

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**Author:** [@dwventer](https://discourse.vtk.org/u/dwventer)\
**Replies:** 0\
**Last updated:** [December 9, 2021, 5:58am UTC](https://discourse.vtk.org/t/clipping-data-only-on-area-selected/7375 "2021-12-09T05:58:20Z")

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I have an image of a human that I need to clip the selected area only(e.g. an arm or leg). My methodology: First pick two points on the area I want to cut. Calculate the plane normals that will be perpendicular to t…

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## [How to draw overley on volume rendering surface](https://discourse.vtk.org/t/how-to-draw-overley-on-volume-rendering-surface/7374)

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**Author:** [@Behtgod](https://discourse.vtk.org/u/Behtgod)\
**Replies:** 0\
**Last updated:** [December 9, 2021, 5:48am UTC](https://discourse.vtk.org/t/how-to-draw-overley-on-volume-rendering-surface/7374 "2021-12-09T05:48:05Z")

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Hello, every one! I want to implement the features similar to the rendering widget of MRICron by VTK. But I have no idea how the MRICron draw a overlay at volume rendering surface. It looks like bellow: The base vo…

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## [Unable to Implement imageCrop Filter](https://discourse.vtk.org/t/unable-to-implement-imagecrop-filter/7254)

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**Author:** [@simplyvish](https://discourse.vtk.org/u/simplyvish)\
**Replies:** 7\
**Last updated:** [December 9, 2021, 5:46am UTC](https://discourse.vtk.org/t/unable-to-implement-imagecrop-filter/7254 "2021-12-09T05:46:59Z")

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I’m trying to implement ImageCrop filter on my volume file. I have downloaded the vtk.js examples and able to run ImageCropFilter example. I tried implementing same separately but getting error in the very first step i.e…

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## [Picking for 3D Volumes](https://discourse.vtk.org/t/picking-for-3d-volumes/5607)

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**Author:** [@Chuck\_Spencer](https://discourse.vtk.org/u/Chuck_Spencer)\
**Replies:** 6\
**Last updated:** [December 8, 2021, 4:33pm UTC](https://discourse.vtk.org/t/picking-for-3d-volumes/5607 "2021-12-08T16:33:33Z")

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I’m loading in a vtkVolume and I need to get the value of the voxel a user is clicking on. I’m struggling to figure out the correct way to do this. I gather that the CellPicker and PointPicker are for geometry, not volum…

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## [Should a filter request current UPDATE\_TIME\_STEP from input or output?](https://discourse.vtk.org/t/should-a-filter-request-current-update-time-step-from-input-or-output/7373)

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**Author:** [@moritz-h](https://discourse.vtk.org/u/moritz-h)\
**Replies:** 0\
**Last updated:** [December 8, 2021, 3:07pm UTC](https://discourse.vtk.org/t/should-a-filter-request-current-update-time-step-from-input-or-output/7373 "2021-12-08T15:07:12Z")

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I want to get the current timestep (as selected in ParaView) within a filter. Looking into other VTK filters and trying to understand what UPDATE\_TIME\_STEP is for, I think I should do this by getting UPDATE\_TIME\_STEP fro…

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## [Problem using release build and mac build of vtk java wrapping](https://discourse.vtk.org/t/problem-using-release-build-and-mac-build-of-vtk-java-wrapping/7369)

<div class="topic-metadata">

**Author:** [@taol8](https://discourse.vtk.org/u/taol8)\
**Replies:** 0\
**Last updated:** [December 8, 2021, 12:47pm UTC](https://discourse.vtk.org/t/problem-using-release-build-and-mac-build-of-vtk-java-wrapping/7369 "2021-12-08T12:47:17Z")

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Hello all, First of all, my apologies if this question has already been asked and/or resolved, but I haven’t seen anyone else with the same issue as I have. I’ve been using the vtk java wrapping to develop a plugin on …

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## [vtkVRMLImporter incorrectly displays the result of the import](https://discourse.vtk.org/t/vtkvrmlimporter-incorrectly-displays-the-result-of-the-import/7358)

<div class="topic-metadata">

**Author:** [@DX130](https://discourse.vtk.org/u/DX130)\
**Replies:** 1\
**Last updated:** [December 8, 2021, 8:19am UTC](https://discourse.vtk.org/t/vtkvrmlimporter-incorrectly-displays-the-result-of-the-import/7358 "2021-12-08T08:19:25Z")

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hello, I have some trouble importing files using vtkVRMLImporter.The details are as follows This is the exported reconstruction result This is the imported reconstruction result I also cannot modify any camera pr…

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## [vtkRenderer and vtkRenderWindow have different size when inside wxVTKRenderWindowInteractor](https://discourse.vtk.org/t/vtkrenderer-and-vtkrenderwindow-have-different-size-when-inside-wxvtkrenderwindowinteractor/7362)

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**Author:** [@brogos](https://discourse.vtk.org/u/brogos)\
**Replies:** 0\
**Last updated:** [December 8, 2021, 2:17am UTC](https://discourse.vtk.org/t/vtkrenderer-and-vtkrenderwindow-have-different-size-when-inside-wxvtkrenderwindowinteractor/7362 "2021-12-08T02:17:58Z")

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Hi, I was doing some testing with VTK and WXPython in a MacBook Air M1. I’m using VTK 9.1.0 and WXPython 4.1.1. One thing that I noticed is vtkRenderer and vtkRenderWindow when inside a wxVTKRenderWindowInteractor have t…

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## [How to use original OpenGL in VTK program?](https://discourse.vtk.org/t/how-to-use-original-opengl-in-vtk-program/4636)

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**Author:** [@xyh](https://discourse.vtk.org/u/xyh)\
**Replies:** 7\
**Last updated:** [December 7, 2021, 8:42pm UTC](https://discourse.vtk.org/t/how-to-use-original-opengl-in-vtk-program/4636 "2021-12-07T20:42:56Z")

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I am new to vtk, can you tell me how to use vtk and opengl in the one window (such as QVTKOpenGLWindow)? For examle, there is a cube painted by vtk, how to add a triangle by opengl in same window? Thanks.

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## [the speed is too slow for vtkWindowToImageFilter, how to speed it?](https://discourse.vtk.org/t/the-speed-is-too-slow-for-vtkwindowtoimagefilter-how-to-speed-it/2396)

<div class="topic-metadata">

**Author:** [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)\
**Replies:** 15\
**Last updated:** [December 7, 2021, 6:27pm UTC](https://discourse.vtk.org/t/the-speed-is-too-slow-for-vtkwindowtoimagefilter-how-to-speed-it/2396 "2021-12-07T18:27:47Z")

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Currently, we need to use vtk in my project. We want to obtain the off sreen rendering picture and show it. We use vtkWindowToImageFilter to obtain the rendering picture. However, we find it’s too slow. My code is: from…

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## [How to get labelmap data array returned from vtkPaintFilter](https://discourse.vtk.org/t/how-to-get-labelmap-data-array-returned-from-vtkpaintfilter/7347)

<div class="topic-metadata">

**Author:** [@shanebenlolo](https://discourse.vtk.org/u/shanebenlolo)\
**Replies:** 2\
**Last updated:** [December 7, 2021, 3:47pm UTC](https://discourse.vtk.org/t/how-to-get-labelmap-data-array-returned-from-vtkpaintfilter/7347 "2021-12-07T15:47:29Z")

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I have a paint filter with a method getLabelMap(), which returns an object of methods. I am trying to get the typed array, which holds the values of the vtkDataArray associated with the label map. Is there a method that …

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## [Quickly access points of a vtkPoints with vtkIdType](https://discourse.vtk.org/t/quickly-access-points-of-a-vtkpoints-with-vtkidtype/7354)

<div class="topic-metadata">

**Author:** [@Julienchz](https://discourse.vtk.org/u/Julienchz)\
**Replies:** 0\
**Last updated:** [December 7, 2021, 11:39am UTC](https://discourse.vtk.org/t/quickly-access-points-of-a-vtkpoints-with-vtkidtype/7354 "2021-12-07T11:39:04Z")

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Hello, I have a vtkIdTypeArray or a vtkIdList referring to points inside a vtkPoints, how can I access quickly those points to render them without using vtkSelectionNode (too long with a large pointcloud) ? Thanks for …

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## [Send progress through web socket](https://discourse.vtk.org/t/send-progress-through-web-socket/7345)

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**Author:** [@no2497](https://discourse.vtk.org/u/no2497)\
**Replies:** 3\
**Last updated:** [December 6, 2021, 6:41pm UTC](https://discourse.vtk.org/t/send-progress-through-web-socket/7345 "2021-12-06T18:41:58Z")

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Hi While reading my DICOM series I want to send a message to the server notifying the current progress of the reading. I found out that there is the .addObserver() method which allows to register some events of a vtkObj…

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## [A question about vtkStructuredGrid](https://discourse.vtk.org/t/a-question-about-vtkstructuredgrid/7318)

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**Author:** [@KeyboardMan](https://discourse.vtk.org/u/KeyboardMan)\
**Replies:** 11\
**Last updated:** [December 6, 2021, 6:00pm UTC](https://discourse.vtk.org/t/a-question-about-vtkstructuredgrid/7318 "2021-12-06T18:00:18Z")

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I try to use vtkStructuredGrid to draw the grid in the polar coordinate system。But the hexahedral cell in vtkCellType is not fan-shaped。 I found this when I was looking for information（like c）, but it didn’t explain h…

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## [Why is there no color in the scene I exported with vtkVRMLExporter](https://discourse.vtk.org/t/why-is-there-no-color-in-the-scene-i-exported-with-vtkvrmlexporter/7344)

<div class="topic-metadata">

**Author:** [@DX130](https://discourse.vtk.org/u/DX130)\
**Replies:** 1\
**Last updated:** [December 6, 2021, 3:39pm UTC](https://discourse.vtk.org/t/why-is-there-no-color-in-the-scene-i-exported-with-vtkvrmlexporter/7344 "2021-12-06T15:39:20Z")

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I want to export the result, but there is always no correct color after opening it with ParaView. If you have any other suggestions please let me know. polydata = vtkAppendPolyData() reader = vtkNIFTIImageReader() …

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## [Cannot perform a minimal build from master without Parallel modules](https://discourse.vtk.org/t/cannot-perform-a-minimal-build-from-master-without-parallel-modules/7298)

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**Author:** [@biagas](https://discourse.vtk.org/u/biagas)\
**Replies:** 3\
**Last updated:** [December 4, 2021, 4:31pm UTC](https://discourse.vtk.org/t/cannot-perform-a-minimal-build-from-master-without-parallel-modules/7298 "2021-12-04T16:31:21Z")

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I am performing a minimal build of VTK master with these initial cache settings: BUILD\_SHARED\_LIBS:BOOL=true VTK\_LEGACY\_REMOVE:BOOL=true VTK\_DATA\_EXCLUDE\_FROM\_ALL:BOOL=true VTK\_FORBID\_DOWNLOADS:BOOL=true VTK\_DEBUG\_MODU…

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## [vtkStreamTracer recent changes](https://discourse.vtk.org/t/vtkstreamtracer-recent-changes/7325)

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**Author:** [@will.schroeder](https://discourse.vtk.org/u/will.schroeder)\
**Replies:** 3\
**Last updated:** [December 4, 2021, 4:30pm UTC](https://discourse.vtk.org/t/vtkstreamtracer-recent-changes/7325 "2021-12-04T16:30:42Z")

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FYI vtkStreamTracer had been threaded (one thread per streamline). This is a complex change and there may be residual issues - please let me know if you come across anything. One issue I am seeing on a few Rogue Researc…

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## [Better labeling of issues in GitLab](https://discourse.vtk.org/t/better-labeling-of-issues-in-gitlab/7273)

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**Author:** [@nocnokneo](https://discourse.vtk.org/u/nocnokneo)\
**Replies:** 3\
**Last updated:** [December 4, 2021, 6:17am UTC](https://discourse.vtk.org/t/better-labeling-of-issues-in-gitlab/7273 "2021-12-04T06:17:03Z")

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As part of the validation of the Software Of Unknown Provenance (SOUP) in our medical device we need to review all know issues to see if any pose a safety risk. Using a risk based approach, we filter out issues that, for…

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## [Filter for deleting isolated voxels](https://discourse.vtk.org/t/filter-for-deleting-isolated-voxels/7328)

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**Author:** [@gaston-perret](https://discourse.vtk.org/u/gaston-perret)\
**Replies:** 1\
**Last updated:** [December 3, 2021, 10:12pm UTC](https://discourse.vtk.org/t/filter-for-deleting-isolated-voxels/7328 "2021-12-03T22:12:18Z")

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Hello. I have a voxel representation of a volume (mask) and I need to clean all the voxels that are not connected to the main volume. I was wondering if there is an existing filter that could help me identify isolated …

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## [I need help with create widget by state](https://discourse.vtk.org/t/i-need-help-with-create-widget-by-state/7294)

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**Author:** [@Maksymilian\_Mlocek](https://discourse.vtk.org/u/Maksymilian_Mlocek)\
**Replies:** 3\
**Last updated:** [December 3, 2021, 9:10pm UTC](https://discourse.vtk.org/t/i-need-help-with-create-widget-by-state/7294 "2021-12-03T21:10:01Z")

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Hi, I try create widget for example line widget by state. I create line widget on scene next I remove it and I would like to create the same widget in the same place on scene from state of the widget but I don’t know how…

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## [vtkimagedata scalar value at specific point(world point)](https://discourse.vtk.org/t/vtkimagedata-scalar-value-at-specific-point-world-point/7312)

<div class="topic-metadata">

**Author:** [@Hyunwoo\_Kim](https://discourse.vtk.org/u/Hyunwoo_Kim)\
**Replies:** 1\
**Last updated:** [December 3, 2021, 8:59pm UTC](https://discourse.vtk.org/t/vtkimagedata-scalar-value-at-specific-point-world-point/7312 "2021-12-03T20:59:17Z")

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Hello, I’m trying to get scalar from vtkimagedata I set scalars to the vtkimagedata (0,1,2,3,4,5, etc) And I want to get interpolated data such as 0.99955, 1.4325… at a single 3D point which is inside the bound of imag…

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## [vtkImageAppend and image origin](https://discourse.vtk.org/t/vtkimageappend-and-image-origin/7327)

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**Author:** [@WailmerPail](https://discourse.vtk.org/u/WailmerPail)\
**Replies:** 0\
**Last updated:** [December 3, 2021, 2:06pm UTC](https://discourse.vtk.org/t/vtkimageappend-and-image-origin/7327 "2021-12-03T14:06:34Z")

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Hi Teams, I want to stack different 3d-images together. I understand that this class cannot support images with different spacing, but I found that it also does not support the origin of images. The z-order of the imag…

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## [QuadratureSchemeDefinition and data arrays](https://discourse.vtk.org/t/quadratureschemedefinition-and-data-arrays/7326)

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**Author:** [@Sagues](https://discourse.vtk.org/u/Sagues)\
**Replies:** 0\
**Last updated:** [December 3, 2021, 12:54pm UTC](https://discourse.vtk.org/t/quadratureschemedefinition-and-data-arrays/7326 "2021-12-03T12:54:03Z")

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I suppose that QuadratureSchemeDefinition allows to define gauss points schemes to integrate data in cells. However I do not know how link QuadratureSchemeDefinition in DoubleArray or other type of celldata array. Thank…

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## [I would like to ask a question about vtkassembly. The problem is more complex and is written in the content](https://discourse.vtk.org/t/i-would-like-to-ask-a-question-about-vtkassembly-the-problem-is-more-complex-and-is-written-in-the-content/7323)

<div class="topic-metadata">

**Author:** [@Huzhikun](https://discourse.vtk.org/u/Huzhikun)\
**Replies:** 0\
**Last updated:** [December 3, 2021, 8:08am UTC](https://discourse.vtk.org/t/i-would-like-to-ask-a-question-about-vtkassembly-the-problem-is-more-complex-and-is-written-in-the-content/7323 "2021-12-03T08:08:41Z")

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When I use vtkassembly for assembly, it is assumed that there are two objects in my space at this time, but these two objects are added in render in the form of actors. Adding an actor to the assembly at this time will r…

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## [voxel from multiple vtkImageData and vtkTransformFilter](https://discourse.vtk.org/t/voxel-from-multiple-vtkimagedata-and-vtktransformfilter/7320)

<div class="topic-metadata">

**Author:** [@riki](https://discourse.vtk.org/u/riki)\
**Replies:** 0\
**Last updated:** [December 3, 2021, 7:07am UTC](https://discourse.vtk.org/t/voxel-from-multiple-vtkimagedata-and-vtktransformfilter/7320 "2021-12-03T07:07:35Z")

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Hi I am working on drawing an ultrasound image in 3D space. If I have multiple data with a set of images and their corresponding rotation and movement parameters (affine transformation matrices), can I render them as vo…

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## [vtkOpenFOAMReader : get bounding box of simulation ?](https://discourse.vtk.org/t/vtkopenfoamreader-get-bounding-box-of-simulation/7308)

<div class="topic-metadata">

**Author:** [@Nicholas\_Yue](https://discourse.vtk.org/u/Nicholas_Yue)\
**Replies:** 1\
**Last updated:** [December 3, 2021, 12:10am UTC](https://discourse.vtk.org/t/vtkopenfoamreader-get-bounding-box-of-simulation/7308 "2021-12-03T00:10:52Z")

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Hi, I am reading in a vtkOpenFOAMReader object in C++ Independently I can see the computational bounds in Paraview. What methods I can call on the object in C++ to query the computational bounds of the FOAM file ? Do …

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## ["Flat index" for vtkDataObjectTree's iterators](https://discourse.vtk.org/t/flat-index-for-vtkdataobjecttrees-iterators/7313)

<div class="topic-metadata">

**Author:** [@tigarmo](https://discourse.vtk.org/u/tigarmo)\
**Replies:** 4\
**Last updated:** [December 2, 2021, 7:01pm UTC](https://discourse.vtk.org/t/flat-index-for-vtkdataobjecttrees-iterators/7313 "2021-12-02T19:01:19Z")

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Hi everyone, It’s my understanding that for composite objects the “flat index” refers to the “subdata” inside the composite, and that this index is 0-based as usual. Therefore, it looks like there might be a bug with vt…

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