# Latest

**URL:** https://discourse.vtk.org/latest.md?page=105

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

**Page:** 106

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## [How to create dual-colored sphere](https://discourse.vtk.org/t/how-to-create-dual-colored-sphere/10215)

<div class="topic-metadata">

**Author:** [@abstracted](https://discourse.vtk.org/u/abstracted)\
**Replies:** 1\
**Last updated:** [December 15, 2022, 11:15pm UTC](https://discourse.vtk.org/t/how-to-create-dual-colored-sphere/10215 "2022-12-15T23:15:07Z")

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Hello all, I’d like to create partially colored spheres which always face the camera. Partially colored means exactly 2 colors, and the fraction of 1 color to another varies based on the context. The sphere can be colore…

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## [Merge connected coplanar faces](https://discourse.vtk.org/t/merge-connected-coplanar-faces/10196)

<div class="topic-metadata">

**Author:** [@Tim\_Hutton](https://discourse.vtk.org/u/Tim_Hutton)\
**Replies:** 4\
**Last updated:** [December 15, 2022, 5:05pm UTC](https://discourse.vtk.org/t/merge-connected-coplanar-faces/10196 "2022-12-15T17:05:16Z")

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Is there a filter in VTK to merge connected coplanar faces? Example image showing a case where a cube has triangulated faces. The desired output has square faces. Thanks, Tim

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## [Named Selection in VTK](https://discourse.vtk.org/t/named-selection-in-vtk/10180)

<div class="topic-metadata">

**Author:** [@MicK7](https://discourse.vtk.org/u/MicK7)\
**Replies:** 1\
**Last updated:** [December 14, 2022, 11:47pm UTC](https://discourse.vtk.org/t/named-selection-in-vtk/10180 "2022-12-14T23:47:08Z")

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Hello, I have seen that conduit has a nice Explicit Selection protocol (Partitioning — Conduit 0.8.4 documentation). Is there a way to generate a kind of VTK object to represent an Explicit Selection (meaning block id +…

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## [vtkClipClosedSurface with RGBA](https://discourse.vtk.org/t/vtkclipclosedsurface-with-rgba/10140)

<div class="topic-metadata">

**Author:** [@Alireza](https://discourse.vtk.org/u/Alireza)\
**Replies:** 7\
**Last updated:** [December 14, 2022, 7:04pm UTC](https://discourse.vtk.org/t/vtkclipclosedsurface-with-rgba/10140 "2022-12-14T19:04:17Z")

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In vtk.js, I would like to cut through a surface and show it overlayed in a volume rendering but with RGBA. Something like below but in the sphere area, I want the underlying volume to get shown (since Sphere clipped sur…

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## [How can I generate the same Meniscus model?](https://discourse.vtk.org/t/how-can-i-generate-the-same-meniscus-model/10164)

<div class="topic-metadata">

**Author:** [@wyc7894512](https://discourse.vtk.org/u/wyc7894512)\
**Replies:** 1\
**Last updated:** [December 14, 2022, 3:53pm UTC](https://discourse.vtk.org/t/how-can-i-generate-the-same-meniscus-model/10164 "2022-12-14T15:53:11Z")

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Hello, I split the meniscus from MRI and input it, but this result is not what I expected. I would like to generate a model similar to the real meniscus. I attach the snippet code. Please, could you help me to find a s…

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## [Repeated interpolation between static unstructured grids](https://discourse.vtk.org/t/repeated-interpolation-between-static-unstructured-grids/10192)

<div class="topic-metadata">

**Author:** [@lv-426](https://discourse.vtk.org/u/lv-426)\
**Replies:** 0\
**Last updated:** [December 14, 2022, 2:01pm UTC](https://discourse.vtk.org/t/repeated-interpolation-between-static-unstructured-grids/10192 "2022-12-14T14:01:50Z")

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Hello, I am interpolating from an unstructured fine grid 1 to an unstructured coarse grid 2 many times over with changing data (both grids stay the same). I am wondering if it is possible to speed up the process so that…

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## [Wrong parameters in exported MTL](https://discourse.vtk.org/t/wrong-parameters-in-exported-mtl/10185)

<div class="topic-metadata">

**Author:** [@ARI31](https://discourse.vtk.org/u/ARI31)\
**Replies:** 0\
**Last updated:** [December 14, 2022, 8:08am UTC](https://discourse.vtk.org/t/wrong-parameters-in-exported-mtl/10185 "2022-12-14T08:08:45Z")

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Hello, I am using VTK 9.2 (from pip) to generate height maps for robotics simulators, but I run into some issues when trying to display them in the simulators (Gazebo 9, and Isaac Sim). What’s happening is that the “Ka”…

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## [vtkPolyData : add attribute/annotation](https://discourse.vtk.org/t/vtkpolydata-add-attribute-annotation/10148)

<div class="topic-metadata">

**Author:** [@Nicholas\_Yue](https://discourse.vtk.org/u/Nicholas_Yue)\
**Replies:** 2\
**Last updated:** [December 14, 2022, 6:33am UTC](https://discourse.vtk.org/t/vtkpolydata-add-attribute-annotation/10148 "2022-12-14T06:33:13Z")

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Hi, I wish to record some meta data regarding the source information that goes into the creation of a given vtkPolyData (for versioning/history/tracking purpose) Is there some way to add such sting/integer information …

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## [How to save the 3D image of the result of volume rendering algorithm as a 3D file](https://discourse.vtk.org/t/how-to-save-the-3d-image-of-the-result-of-volume-rendering-algorithm-as-a-3d-file/10183)

<div class="topic-metadata">

**Author:** [@zbz](https://discourse.vtk.org/u/zbz)\
**Replies:** 0\
**Last updated:** [December 14, 2022, 5:44am UTC](https://discourse.vtk.org/t/how-to-save-the-3d-image-of-the-result-of-volume-rendering-algorithm-as-a-3d-file/10183 "2022-12-14T05:44:43Z")

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How to save the 3D image of the result of volume rendering algorithm as a 3D file

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## [Editing \*vtu files which are part of \*pvtu and saving them](https://discourse.vtk.org/t/editing-vtu-files-which-are-part-of-pvtu-and-saving-them/10177)

<div class="topic-metadata">

**Author:** [@rnp](https://discourse.vtk.org/u/rnp)\
**Replies:** 0\
**Last updated:** [December 13, 2022, 4:54pm UTC](https://discourse.vtk.org/t/editing-vtu-files-which-are-part-of-pvtu-and-saving-them/10177 "2022-12-13T16:54:33Z")

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Hello, I am new to using this library. I have a bunch of \*vtu files which are part of \*pvtu generated from deal.ii. I want to make some changes to the point-data present - delete a few variables and add a few more manu…

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## [Help with vtk wasm C++ and volume rendering vs vtk.js](https://discourse.vtk.org/t/help-with-vtk-wasm-c-and-volume-rendering-vs-vtk-js/10132)

<div class="topic-metadata">

**Author:** [@Kalsyc](https://discourse.vtk.org/u/Kalsyc)\
**Replies:** 5\
**Last updated:** [December 13, 2022, 2:42pm UTC](https://discourse.vtk.org/t/help-with-vtk-wasm-c-and-volume-rendering-vs-vtk-js/10132 "2022-12-13T14:42:24Z")

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Hi all, Before, I start, I just want to say that vtk.js is an absolute joy to work with, and appreciate the people @ kitware who have been working on it. However, right now I am finding vtk.js to not be enough for what…

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## [append new scalar field to existing vtk file](https://discourse.vtk.org/t/append-new-scalar-field-to-existing-vtk-file/10175)

<div class="topic-metadata">

**Author:** [@garcfd](https://discourse.vtk.org/u/garcfd)\
**Replies:** 0\
**Last updated:** [December 13, 2022, 12:34pm UTC](https://discourse.vtk.org/t/append-new-scalar-field-to-existing-vtk-file/10175 "2022-12-13T12:34:50Z")

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I want to get started with python vtk, by reading an vtk file (slice) and then add a new scalar field to the existing velocity magnitude field, and then write out the new modified vtk file (ideally with an image file too…

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## [trame multi-user setting](https://discourse.vtk.org/t/trame-multi-user-setting/10171)

<div class="topic-metadata">

**Author:** [@jackshen2028](https://discourse.vtk.org/u/jackshen2028)\
**Replies:** 2\
**Last updated:** [December 13, 2022, 6:49am UTC](https://discourse.vtk.org/t/trame-multi-user-setting/10171 "2022-12-13T06:49:28Z")

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Dear vtk support, First of all, thanks for providing these wonderfull tools. Currently I am using trame to create a web app to similar things like cloud-based FEM simulation. For multi-user support, I found some materia…

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## [vtkVoronoi2D doesn't work with simple cube](https://discourse.vtk.org/t/vtkvoronoi2d-doesnt-work-with-simple-cube/10169)

<div class="topic-metadata">

**Author:** [@AndreAhmed](https://discourse.vtk.org/u/AndreAhmed)\
**Replies:** 1\
**Last updated:** [December 13, 2022, 2:09am UTC](https://discourse.vtk.org/t/vtkvoronoi2d-doesnt-work-with-simple-cube/10169 "2022-12-13T02:09:10Z")

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Hello, I’m reading an obj file “cube” which is a simple cube, and would like to project voronoi diagram on it. I’ve tried the following code, but it either crashes, or it stays in infinite loop. Kindly find the attach…

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## [VTK9.2.2 Python Cylinder example will not run on Ubuntu from fresh conda (or pip) install](https://discourse.vtk.org/t/vtk9-2-2-python-cylinder-example-will-not-run-on-ubuntu-from-fresh-conda-or-pip-install/10085)

<div class="topic-metadata">

**Author:** [@connorferster](https://discourse.vtk.org/u/connorferster)\
**Replies:** 7\
**Last updated:** [December 13, 2022, 12:52am UTC](https://discourse.vtk.org/t/vtk9-2-2-python-cylinder-example-will-not-run-on-ubuntu-from-fresh-conda-or-pip-install/10085 "2022-12-13T00:52:58Z")

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Hi there! I am trying to get vtk to run and I am getting the following error on the Python Cylinder (“hello world”) example. libGL error: MESA-LOADER: failed to open iris: /usr/lib/dri/iris\_dri.so: cannot open shared o…

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## [Can we assume that a vtkCell will hold a vtkPoints object with a double type?](https://discourse.vtk.org/t/can-we-assume-that-a-vtkcell-will-hold-a-vtkpoints-object-with-a-double-type/10149)

<div class="topic-metadata">

**Author:** [@spyridon97](https://discourse.vtk.org/u/spyridon97)\
**Replies:** 6\
**Last updated:** [December 12, 2022, 3:26pm UTC](https://discourse.vtk.org/t/can-we-assume-that-a-vtkcell-will-hold-a-vtkpoints-object-with-a-double-type/10149 "2022-12-12T15:26:42Z")

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All the vtkCell subclasses when created rhwy instantiate a vtkPoints object with VTK\_DOUBLE, which means that the vtkDataArray holding the points of a cell will be a vtkDoubleArray. //-----------------------------------…

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## [Python: Reading, Calculate, Write Out](https://discourse.vtk.org/t/python-reading-calculate-write-out/1138)

<div class="topic-metadata">

**Author:** [@Horus](https://discourse.vtk.org/u/Horus)\
**Replies:** 6\
**Last updated:** [December 12, 2022, 5:57pm UTC](https://discourse.vtk.org/t/python-reading-calculate-write-out/1138 "2022-12-12T17:57:25Z")

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Hello, I want to read in a VTK file, evaluate some function on it and write the file back, including the function result. All that, using the Python VTK interface. So far I got: from vtk import \* reader = vtkDataSetR…

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## [Vtk point cloud display multiple points (cluster)](https://discourse.vtk.org/t/vtk-point-cloud-display-multiple-points-cluster/10162)

<div class="topic-metadata">

**Author:** [@nikhilmakkar2345](https://discourse.vtk.org/u/nikhilmakkar2345)\
**Replies:** 2\
**Last updated:** [December 12, 2022, 4:53pm UTC](https://discourse.vtk.org/t/vtk-point-cloud-display-multiple-points-cluster/10162 "2022-12-12T16:53:42Z")

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Cannot visualize the points around one of the selected points in point cloud. Not sure what I am missing. I used the below code. What it does is just takes a pointcloud and convert it into polydata and visualize it. Afte…

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## [Is it possible to combine two inputs into one while rendering in MultiSliceImageMapper?](https://discourse.vtk.org/t/is-it-possible-to-combine-two-inputs-into-one-while-rendering-in-multisliceimagemapper/9866)

<div class="topic-metadata">

**Author:** [@Yuvi-416](https://discourse.vtk.org/u/Yuvi-416)\
**Replies:** 5\
**Last updated:** [December 12, 2022, 4:43pm UTC](https://discourse.vtk.org/t/is-it-possible-to-combine-two-inputs-into-one-while-rendering-in-multisliceimagemapper/9866 "2022-12-12T16:43:55Z")

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Hello everyone, I am trying to render two images into one using the MultiSliceImageMapper algorithm. I have one image with two channels and want to render them in MultiSliceImageMapper. I can perform MultiSliceImageMap…

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## [vtkImageMathematics as a pipeline?](https://discourse.vtk.org/t/vtkimagemathematics-as-a-pipeline/10154)

<div class="topic-metadata">

**Author:** [@XGDragon](https://discourse.vtk.org/u/XGDragon)\
**Replies:** 3\
**Last updated:** [December 12, 2022, 4:30pm UTC](https://discourse.vtk.org/t/vtkimagemathematics-as-a-pipeline/10154 "2022-12-12T16:30:11Z")

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I have learned that using a.SetInputConnection(b.GetOutputPort()), you establish a pipeline connection such that when you b.Update(), it will also update a. For vtkImageMathematics, it appears there is no way to establi…

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## [problem in: vtk Android Render Window Interactor](https://discourse.vtk.org/t/problem-in-vtk-android-render-window-interactor/10167)

<div class="topic-metadata">

**Author:** [@perphy](https://discourse.vtk.org/u/perphy)\
**Replies:** 0\
**Last updated:** [December 12, 2022, 4:14pm UTC](https://discourse.vtk.org/t/problem-in-vtk-android-render-window-interactor/10167 "2022-12-12T16:14:58Z")

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Hi: I am using vtk9.2.2 to run the official android example https://gitlab.kitware.com/vtk/vtk/-/tree/master/Examples/Android/NativeVTK I meet an error in logcat I locate the source file that . How can I solve i…

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## [Converting several splines into 3D Mesh](https://discourse.vtk.org/t/converting-several-splines-into-3d-mesh/10166)

<div class="topic-metadata">

**Author:** [@AndreAhmed](https://discourse.vtk.org/u/AndreAhmed)\
**Replies:** 1\
**Last updated:** [December 12, 2022, 1:54pm UTC](https://discourse.vtk.org/t/converting-several-splines-into-3d-mesh/10166 "2022-12-12T13:54:07Z")

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Hello, I’m sorry if its a repeated question, but I have the following input and want to generate the output like that, does vtk support something like the following

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## [Foreign Function Interface Generation for Dart/Flutter - ffigen](https://discourse.vtk.org/t/foreign-function-interface-generation-for-dart-flutter-ffigen/10160)

<div class="topic-metadata">

**Author:** [@giiyms](https://discourse.vtk.org/u/giiyms)\
**Replies:** 3\
**Last updated:** [December 12, 2022, 1:48pm UTC](https://discourse.vtk.org/t/foreign-function-interface-generation-for-dart-flutter-ffigen/10160 "2022-12-12T13:48:45Z")

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Hello, I would like to attempt converting the VTK headers so Flutter/Dart can talk to it directly. Does anyone know / can point me to the core/barebones headers needed for VTK to work? If anyone is interested in helpi…

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## [vtk三维重建后获得图片](https://discourse.vtk.org/t/vtk/10147)

<div class="topic-metadata">

**Author:** [@zbz](https://discourse.vtk.org/u/zbz)\
**Replies:** 1\
**Last updated:** [December 12, 2022, 8:22am UTC](https://discourse.vtk.org/t/vtk/10147 "2022-12-12T08:22:03Z")

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如何获取vtk三维重建后的个方位的图片

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## [points and texture coordinate in vtkPolyData vtkOBJReader ?](https://discourse.vtk.org/t/points-and-texture-coordinate-in-vtkpolydata-vtkobjreader/10058)

<div class="topic-metadata">

**Author:** [@Nicholas\_Yue](https://discourse.vtk.org/u/Nicholas_Yue)\
**Replies:** 4\
**Last updated:** [December 12, 2022, 8:15am UTC](https://discourse.vtk.org/t/points-and-texture-coordinate-in-vtkpolydata-vtkobjreader/10058 "2022-12-12T08:15:25Z")

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I am reading in an OBJ file that has both points and texture coordinate information, I am reading them in via vtkOBJReader How should I go about extracting those information ? Should I go via Cell or Poly ? #include \<v…

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## [vtkTextProperty / vtkPointSetToLabelHierarchy offset strange behavior](https://discourse.vtk.org/t/vtktextproperty-vtkpointsettolabelhierarchy-offset-strange-behavior/10092)

<div class="topic-metadata">

**Author:** [@CharInt0](https://discourse.vtk.org/u/CharInt0)\
**Replies:** 3\
**Last updated:** [December 12, 2022, 7:50am UTC](https://discourse.vtk.org/t/vtktextproperty-vtkpointsettolabelhierarchy-offset-strange-behavior/10092 "2022-12-12T07:50:12Z")

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Hi, (VTK 9.2.2, C++ language) I am trying to position some labels near some points at a distance using the class vtkTextProperty and vtkPointSetToLabelHierarchy, but I am obtaining unexpected results. The vtkTextPrope…

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## [How to evenly cut the pipe model through the method in VTK](https://discourse.vtk.org/t/how-to-evenly-cut-the-pipe-model-through-the-method-in-vtk/10156)

<div class="topic-metadata">

**Author:** [@Dwight98](https://discourse.vtk.org/u/Dwight98)\
**Replies:** 2\
**Last updated:** [December 12, 2022, 6:39am UTC](https://discourse.vtk.org/t/how-to-evenly-cut-the-pipe-model-through-the-method-in-vtk/10156 "2022-12-12T06:39:00Z")

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I have a long OBJ model of a mine pipeline, but its direction is not regular in any of the x, y, or z axial directions，I used to use the bounding box to determine the direction of Plane’s cutting for him, but the cut out…

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## [Color a cut plane over unstructured grid](https://discourse.vtk.org/t/color-a-cut-plane-over-unstructured-grid/10135)

<div class="topic-metadata">

**Author:** [@albert](https://discourse.vtk.org/u/albert)\
**Replies:** 1\
**Last updated:** [December 12, 2022, 3:56am UTC](https://discourse.vtk.org/t/color-a-cut-plane-over-unstructured-grid/10135 "2022-12-12T03:56:36Z")

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Hi all. I have a doubt about how to use vtkCutter in my python script. My workflow is: taking an unstructured grid. filter it by a VtkThreshold over a scalar, named e.g. ‘A’ then plot a slice of the filtered-by-thres…

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## [Proplem using vtkPLYWriter with WriteToOutputString = true](https://discourse.vtk.org/t/proplem-using-vtkplywriter-with-writetooutputstring-true/10114)

<div class="topic-metadata">

**Author:** [@dwventer](https://discourse.vtk.org/u/dwventer)\
**Replies:** 3\
**Last updated:** [December 11, 2022, 9:40pm UTC](https://discourse.vtk.org/t/proplem-using-vtkplywriter-with-writetooutputstring-true/10114 "2022-12-11T21:40:43Z")

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Hi, I am trying to use the vtkPLYWriter to write to a std::string. This is an extraction of my code: vtkNew\<vtkPLYWriter\> vtkWriter; vtkWriter-\>WriteToOutputStringOn(); vtkWriter-\>SetFileTypeToBinary(); vtkWriter-\>SetI…

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## [The problem in vtkInteractorStyleImage to set DICOM slice by mousewheel](https://discourse.vtk.org/t/the-problem-in-vtkinteractorstyleimage-to-set-dicom-slice-by-mousewheel/9732)

<div class="topic-metadata">

**Author:** [@a0980543469](https://discourse.vtk.org/u/a0980543469)\
**Replies:** 17\
**Last updated:** [December 11, 2022, 3:08pm UTC](https://discourse.vtk.org/t/the-problem-in-vtkinteractorstyleimage-to-set-dicom-slice-by-mousewheel/9732 "2022-12-11T15:08:36Z")

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When I want to use vtkInteractorStyleImage to overide the mousewheel event, #1 New(); #2 vtkTypeMacro( ,); are show “doesn’t find the function definition” How can I do to solve it? use VTK 9.2.0rc2 VTK-DICOM QT …

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