# Latest

**URL:** https://discourse.vtk.org/latest.md?page=102

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

**Page:** 103

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## [Visualization failed when display two polygon in the same time](https://discourse.vtk.org/t/visualization-failed-when-display-two-polygon-in-the-same-time/10397)

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**Author:** [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)\
**Replies:** 9\
**Last updated:** [January 12, 2023, 1:55pm UTC](https://discourse.vtk.org/t/visualization-failed-when-display-two-polygon-in-the-same-time/10397 "2023-01-12T13:55:42Z")

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I want to display two polygon in one renderer. And the result is: The green and red color indicates two polygons. However, when I rotate it, some part of green color disappear: My environment is: win 10 pytho…

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## [About anti-aliased lines+volume rendering](https://discourse.vtk.org/t/about-anti-aliased-lines-volume-rendering/10410)

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**Author:** [@Xoz](https://discourse.vtk.org/u/Xoz)\
**Replies:** 2\
**Last updated:** [January 12, 2023, 9:13am UTC](https://discourse.vtk.org/t/about-anti-aliased-lines-volume-rendering/10410 "2023-01-12T09:13:41Z")

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Hi everyone, I’ve encountered the situation similar to this topichttps://discourse.vtk.org/t/advice-for-high-quality-anti-aliased-lines-volume-rendering/2141/3 This is the performance on my chrome: Without Volume: …

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## [How to directly export an OBJ model from world coordinates](https://discourse.vtk.org/t/how-to-directly-export-an-obj-model-from-world-coordinates/10428)

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**Author:** [@Dwight98](https://discourse.vtk.org/u/Dwight98)\
**Replies:** 0\
**Last updated:** [January 12, 2023, 8:50am UTC](https://discourse.vtk.org/t/how-to-directly-export-an-obj-model-from-world-coordinates/10428 "2023-01-12T08:50:56Z")

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I want to insert points one by one in vtk by longitude and latitude coordinates of WGS84 and generate polygons, and then stretch this polygon into a three-dimensional model，and finally export to obj format for easy use.H…

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## [How to generate a cylinder from an irregular polygon](https://discourse.vtk.org/t/how-to-generate-a-cylinder-from-an-irregular-polygon/10362)

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**Author:** [@Dwight98](https://discourse.vtk.org/u/Dwight98)\
**Replies:** 4\
**Last updated:** [January 12, 2023, 8:33am UTC](https://discourse.vtk.org/t/how-to-generate-a-cylinder-from-an-irregular-polygon/10362 "2023-01-12T08:33:48Z")

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I want to turn an irregular polygon into a plane through VTK, and then stretch this plane vertically into an irregular cylinder，there are any good ways？I hope that the seniors will give good advice，Sincere thanks！

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## [Feature: vtkObject inheritance without instantiation](https://discourse.vtk.org/t/feature-vtkobject-inheritance-without-instantiation/10426)

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**Author:** [@dcthomp](https://discourse.vtk.org/u/dcthomp)\
**Replies:** 0\
**Last updated:** [January 11, 2023, 8:55pm UTC](https://discourse.vtk.org/t/feature-vtkobject-inheritance-without-instantiation/10426 "2023-01-11T20:55:15Z")

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Summary The vtkObject class which serves as the basis for nearly all of VTK provides nice run-time methods like GetClassName() and IsA() to query objects for their type. These are implemented using the Superclass type-al…

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## [Feature: String tokenization](https://discourse.vtk.org/t/feature-string-tokenization/10425)

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**Author:** [@dcthomp](https://discourse.vtk.org/u/dcthomp)\
**Replies:** 0\
**Last updated:** [January 11, 2023, 8:30pm UTC](https://discourse.vtk.org/t/feature-string-tokenization/10425 "2023-01-11T20:30:02Z")

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Summary VTK now includes a constexpr (compile-time) string hashing algorithm. This enables things such as more legible (and faster) code when comparing a test string to multiple potential matches: #include "vtkStringTok…

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## [where do I find a detailed description of all the XML element attributes in a VTU file?](https://discourse.vtk.org/t/where-do-i-find-a-detailed-description-of-all-the-xml-element-attributes-in-a-vtu-file/10419)

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**Author:** [@bkwilliams](https://discourse.vtk.org/u/bkwilliams)\
**Replies:** 1\
**Last updated:** [January 11, 2023, 6:51pm UTC](https://discourse.vtk.org/t/where-do-i-find-a-detailed-description-of-all-the-xml-element-attributes-in-a-vtu-file/10419 "2023-01-11T18:51:58Z")

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I’m trying to find where I can get all the available attributes for the various elements in a VTK XML file, for example the element in a VTU unstructured grid file. I have some examples but I’m pretty sure they don’t co…

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## [vtkNIFTIImageReader cannot read the origin of NIFTI Image](https://discourse.vtk.org/t/vtkniftiimagereader-cannot-read-the-origin-of-nifti-image/10420)

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**Author:** [@nnzzll](https://discourse.vtk.org/u/nnzzll)\
**Replies:** 1\
**Last updated:** [January 11, 2023, 5:34pm UTC](https://discourse.vtk.org/t/vtkniftiimagereader-cannot-read-the-origin-of-nifti-image/10420 "2023-01-11T17:34:19Z")

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I create a NIFTI image file by using SimpleITK and saved as .nii.gz file. However, when I load it by vtkNIFTIImageReader, the origin of the output vtkImageData turns out to be (0, 0, 0), which is not what I had set in S…

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## [Image transmission, measurement segmentation](https://discourse.vtk.org/t/image-transmission-measurement-segmentation/10417)

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**Author:** [@jane](https://discourse.vtk.org/u/jane)\
**Replies:** 1\
**Last updated:** [January 10, 2023, 4:26pm UTC](https://discourse.vtk.org/t/image-transmission-measurement-segmentation/10417 "2023-01-10T16:26:17Z")

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Hello! I’m more curious about how the remoteview shows the reconstructed image of the medical body in the browser, and when I look at it on the web page, (put that image here), and find that it is transmitted through the…

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## [Always getting STL surface color as black](https://discourse.vtk.org/t/always-getting-stl-surface-color-as-black/10413)

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**Author:** [@patiludayv](https://discourse.vtk.org/u/patiludayv)\
**Replies:** 3\
**Last updated:** [January 10, 2023, 9:46am UTC](https://discourse.vtk.org/t/always-getting-stl-surface-color-as-black/10413 "2023-01-10T09:46:51Z")

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Hi all, I have an STL file. When I open it in STLReader live example (vtk.js), It always shows in black color. Because of which, I am not able to apply color on that surface. Is there is any VTK function is available w…

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## [Some questions about 3D medical image reconstruction and segmentation](https://discourse.vtk.org/t/some-questions-about-3d-medical-image-reconstruction-and-segmentation/10400)

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**Author:** [@HWsir](https://discourse.vtk.org/u/HWsir)\
**Replies:** 3\
**Last updated:** [January 10, 2023, 7:55am UTC](https://discourse.vtk.org/t/some-questions-about-3d-medical-image-reconstruction-and-segmentation/10400 "2023-01-10T07:55:56Z")

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Segmentation of 3D images by mouse sketching, my train of thought Uploading: ~H7W0G67NOIVAG@L\`OWTFKY.png… The Cropping method of vtk ValueMapper performs 3D image segmentation. How do I get the parameters of the SetCr…

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## [failed to convert polydata to volume](https://discourse.vtk.org/t/failed-to-convert-polydata-to-volume/10408)

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**Author:** [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)\
**Replies:** 0\
**Last updated:** [January 9, 2023, 1:55pm UTC](https://discourse.vtk.org/t/failed-to-convert-polydata-to-volume/10408 "2023-01-09T13:55:08Z")

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I want to convert a polydata to volume, and my reference code is: https://kitware.github.io/vtk-examples/site/Cxx/PolyData/PolyDataToImageData/. My polydata is: But the converted imagedata is: There is some unex…

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## [Need help to understand how vtkMachingCube requestData() method is triggled](https://discourse.vtk.org/t/need-help-to-understand-how-vtkmachingcube-requestdata-method-is-triggled/10407)

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**Author:** [@gzt036](https://discourse.vtk.org/u/gzt036)\
**Replies:** 1\
**Last updated:** [January 9, 2023, 9:53am UTC](https://discourse.vtk.org/t/need-help-to-understand-how-vtkmachingcube-requestdata-method-is-triggled/10407 "2023-01-09T09:53:12Z")

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I need to compute vtkMarchingCube via webworker. However, I don’t know how Filters/General/ImageMarchingCubes requestData() method is triggered. Could someone help to shed light on this? Thanks.

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## [Questions about vtkCubeAxesActor](https://discourse.vtk.org/t/questions-about-vtkcubeaxesactor/10405)

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**Author:** [@tong\_yang](https://discourse.vtk.org/u/tong_yang)\
**Replies:** 0\
**Last updated:** [January 9, 2023, 3:32am UTC](https://discourse.vtk.org/t/questions-about-vtkcubeaxesactor/10405 "2023-01-09T03:32:06Z")

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Hello, I have been learning VTK for one year. I met some questions about the vtkCubeAxesActor. I have tried to use SetUserTransform, SetScale, SetPosition and RotateX, but these methods did not work. Abont font，I have …

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## [vtkCubeAxesActor2D (8.2.0), changing axis label font size (does not work)](https://discourse.vtk.org/t/vtkcubeaxesactor2d-8-2-0-changing-axis-label-font-size-does-not-work/1485)

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**Author:** [@francek](https://discourse.vtk.org/u/francek)\
**Replies:** 1\
**Last updated:** [January 9, 2023, 2:55am UTC](https://discourse.vtk.org/t/vtkcubeaxesactor2d-8-2-0-changing-axis-label-font-size-does-not-work/1485 "2023-01-09T02:55:33Z")

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Hi, When I run CubeAxesActor2D example and change the font size from tprop-\>SetFontSize(20); to e.g. tprop-\>SetFontSize(40); the actual font size does not change. Any idea why/how to change label font size? Th…

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## [vtkLineWidget not follow mouse after rerender on vtkImageData change](https://discourse.vtk.org/t/vtklinewidget-not-follow-mouse-after-rerender-on-vtkimagedata-change/10364)

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**Author:** [@tina](https://discourse.vtk.org/u/tina)\
**Replies:** 5\
**Last updated:** [January 8, 2023, 11:48pm UTC](https://discourse.vtk.org/t/vtklinewidget-not-follow-mouse-after-rerender-on-vtkimagedata-change/10364 "2023-01-08T23:48:33Z")

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So I am working on a react app to display live images from backend, on the web page initialise, it will create a live frame scene, which showing a default vtkImageData of size 256 \* 256, then the page will receive a data…

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## [How to exchange the VTI file of a case for a local VTI file?](https://discourse.vtk.org/t/how-to-exchange-the-vti-file-of-a-case-for-a-local-vti-file/10401)

<div class="topic-metadata">

**Author:** [@jane](https://discourse.vtk.org/u/jane)\
**Replies:** 1\
**Last updated:** [January 8, 2023, 9:58pm UTC](https://discourse.vtk.org/t/how-to-exchange-the-vti-file-of-a-case-for-a-local-vti-file/10401 "2023-01-08T21:58:54Z")

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Hello! When I test the official website code case, the following problem occurs when importing local VTI files.Is vtkHttpDataSetReader unable to read vti files on my computer? reader .setUrl(\` http://192.168.1.4:808…

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## [Error GLSL 1.50 is not supported.](https://discourse.vtk.org/t/error-glsl-1-50-is-not-supported/1444)

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**Author:** [@pbazavan](https://discourse.vtk.org/u/pbazavan)\
**Replies:** 4\
**Last updated:** [January 8, 2023, 9:52am UTC](https://discourse.vtk.org/t/error-glsl-1-50-is-not-supported/1444 "2023-01-08T09:52:34Z")

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Hello people, I’m new on this site. I am getting an error when trying to run a simple vtk representation program. The error is “error: GLSL 1.50 is not supported. Supported versions are: 1.10, 1.20, 1.30, 1.00 ES, and…

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## [Convert .vtp to 3d array or tensor](https://discourse.vtk.org/t/convert-vtp-to-3d-array-or-tensor/10385)

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**Author:** [@Nikita\_Litvinenko](https://discourse.vtk.org/u/Nikita_Litvinenko)\
**Replies:** 1\
**Last updated:** [January 7, 2023, 5:36pm UTC](https://discourse.vtk.org/t/convert-vtp-to-3d-array-or-tensor/10385 "2023-01-07T17:36:05Z")

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Hi all! I use the dataset Vascular Model Repository and in it the aorta models are stored in .vtp . I wanted to ask if someone knows if it is possible in any way (at least programmatically, in any programming language) t…

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## [Re-introducing a generic RenderingVR API for retrieving tracker state](https://discourse.vtk.org/t/re-introducing-a-generic-renderingvr-api-for-retrieving-tracker-state/10394)

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**Author:** [@jcfr](https://discourse.vtk.org/u/jcfr)\
**Replies:** 2\
**Last updated:** [January 6, 2023, 7:48am UTC](https://discourse.vtk.org/t/re-introducing-a-generic-renderingvr-api-for-retrieving-tracker-state/10394 "2023-01-06T07:48:07Z")

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This post summarizes offline discussions between @LucasGandel and @jcfr and is intended to help converge to having an API associated with the vtkRenderingVR module allowing to retrieve metadata associated with devices (a…

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## [How to obtain the polydata added in trackball actor interactor.](https://discourse.vtk.org/t/how-to-obtain-the-polydata-added-in-trackball-actor-interactor/10306)

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**Author:** [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)\
**Replies:** 4\
**Last updated:** [January 6, 2023, 2:11pm UTC](https://discourse.vtk.org/t/how-to-obtain-the-polydata-added-in-trackball-actor-interactor/10306 "2023-01-06T14:11:18Z")

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I have a vtkPolyData, and generate a vtkActor. I add this vtkActor to vtkInteractorStyleTrackballActor. After some rotation/pan/spin action, the position/scale/orientation of vtkActor has been changed, but the vtkPolyDat…

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## [How to get the center value of a GLWindow interactor position in ResliceCursorWidget](https://discourse.vtk.org/t/how-to-get-the-center-value-of-a-glwindow-interactor-position-in-reslicecursorwidget/10383)

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**Author:** [@dexter](https://discourse.vtk.org/u/dexter)\
**Replies:** 2\
**Last updated:** [January 6, 2023, 10:52am UTC](https://discourse.vtk.org/t/how-to-get-the-center-value-of-a-glwindow-interactor-position-in-reslicecursorwidget/10383 "2023-01-06T10:52:26Z")

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Hey, I want to set the center of my reslice widget cursor, using the position where we clicked with the mouse in a reslice actor (one of the three views in the ResliceCursorWidget ), I did this obj.interactor.onLeftBu…

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## [vtkTransformPolyDataFilter output a incorrect result](https://discourse.vtk.org/t/vtktransformpolydatafilter-output-a-incorrect-result/10366)

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**Author:** [@zhang-qiang-github](https://discourse.vtk.org/u/zhang-qiang-github)\
**Replies:** 11\
**Last updated:** [January 6, 2023, 9:38am UTC](https://discourse.vtk.org/t/vtktransformpolydatafilter-output-a-incorrect-result/10366 "2023-01-06T09:38:35Z")

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I have a polydata and a transformMatrix. I compute two result: transform the center point of polydata with transformMatrix. transform the polydata with transformMatrix, and get center of the new poly data. I find the …

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## [how to use DistanceWidget ?](https://discourse.vtk.org/t/how-to-use-distancewidget/10388)

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**Author:** [@jane](https://discourse.vtk.org/u/jane)\
**Replies:** 1\
**Last updated:** [January 6, 2023, 8:14am UTC](https://discourse.vtk.org/t/how-to-use-distancewidget/10388 "2023-01-06T08:14:24Z")

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Hello! Through RemoteView, the 3D image is transmitted to the front end, how to apply the widget DistanceWidget for distance measurement? What are the function calls between them?

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## [Interactive operations such as measuring, sketching, etc](https://discourse.vtk.org/t/interactive-operations-such-as-measuring-sketching-etc/10389)

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**Author:** [@mmXIO](https://discourse.vtk.org/u/mmXIO)\
**Replies:** 2\
**Last updated:** [January 6, 2023, 7:55am UTC](https://discourse.vtk.org/t/interactive-operations-such-as-measuring-sketching-etc/10389 "2023-01-06T07:55:50Z")

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Hello, when I was working on web-based 3D visualization of medical images, I used vtkremoteview to display images from the backend on a web page. I’m thinking about whether I can use some widgets of vtk.js to sketch, mea…

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## [\[Bugs\] Issue with compilation vtk to product a vtk.jar](https://discourse.vtk.org/t/bugs-issue-with-compilation-vtk-to-product-a-vtk-jar/10392)

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**Author:** [@aschmit](https://discourse.vtk.org/u/aschmit)\
**Replies:** 3\
**Last updated:** [January 5, 2023, 8:22pm UTC](https://discourse.vtk.org/t/bugs-issue-with-compilation-vtk-to-product-a-vtk-jar/10392 "2023-01-05T20:22:00Z")

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Hello everyone, I have tried to compile the source vtk to producta vtk.jar. But it fails because we have the enum arguments whose are truncated by the parser. The possible origin of this behaviour is the function vtkPa…

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## [What is the concept of ViewProxy?](https://discourse.vtk.org/t/what-is-the-concept-of-viewproxy/10372)

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**Author:** [@YHJ](https://discourse.vtk.org/u/YHJ)\
**Replies:** 2\
**Last updated:** [January 5, 2023, 8:53am UTC](https://discourse.vtk.org/t/what-is-the-concept-of-viewproxy/10372 "2023-01-05T08:53:45Z")

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Hello ! I refer to projects like “VolView” and I’ve seen a lot of component configurations with ViewProxy. I’m asking you a question because it’s hard to understand the concept of VTK.js example and API document. Coul…

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## [How to change scalarbarwidget font properties](https://discourse.vtk.org/t/how-to-change-scalarbarwidget-font-properties/10343)

<div class="topic-metadata">

**Author:** [@BlueKnight7](https://discourse.vtk.org/u/BlueKnight7)\
**Replies:** 6\
**Last updated:** [January 4, 2023, 9:27pm UTC](https://discourse.vtk.org/t/how-to-change-scalarbarwidget-font-properties/10343 "2023-01-04T21:27:13Z")

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I can’t find a way to change the scarlarbarwidget font properties such as size and color. Can anyone help? BK

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## [mat4.lookat matrix VS the view matrix?](https://discourse.vtk.org/t/mat4-lookat-matrix-vs-the-view-matrix/10386)

<div class="topic-metadata">

**Author:** [@Alireza](https://discourse.vtk.org/u/Alireza)\
**Replies:** 0\
**Last updated:** [January 4, 2023, 7:08pm UTC](https://discourse.vtk.org/t/mat4-lookat-matrix-vs-the-view-matrix/10386 "2023-01-04T19:08:58Z")

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Based on couple of webGL resources (links below) the mat4 lookat matrix is the actual matrix that converts the world coordinate into the view coordinates (so basically the view matrix). But in vtk.js source code I see th…

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## ['vtkDICOMImageReader' Errors: 'Couldn't get sorted files', while trying to import a set of .dcm files.](https://discourse.vtk.org/t/vtkdicomimagereader-errors-couldnt-get-sorted-files-while-trying-to-import-a-set-of-dcm-files/10314)

<div class="topic-metadata">

**Author:** [@wang](https://discourse.vtk.org/u/wang)\
**Replies:** 1\
**Last updated:** [January 4, 2023, 4:50pm UTC](https://discourse.vtk.org/t/vtkdicomimagereader-errors-couldnt-get-sorted-files-while-trying-to-import-a-set-of-dcm-files/10314 "2023-01-04T16:50:27Z")

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Hello All, I am trying to run the following example from MedicalDemo4 using Python3. Since my input data is a set of raw CT images, I modified ‘reader = vtkMetaImageReader()’ to ‘reader = vtkDICOMImageReader()’ with ‘r…

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