# Latest

**URL:** https://discourse.vtk.org/latest.md?page=224

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

**Page:** 225

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## [Select and delete a widget](https://discourse.vtk.org/t/select-and-delete-a-widget/2629)

<div class="topic-metadata">

**Author:** [@flaviu2](https://discourse.vtk.org/u/flaviu2)\
**Replies:** 2\
**Last updated:** [February 19, 2020, 3:27pm UTC](https://discourse.vtk.org/t/select-and-delete-a-widget/2629 "2020-02-19T15:27:01Z")

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I am struggle to select an widget in order to delete it. I have an 2d image actor, and over this actor I intend to spread widgets. Nothing special. I have tried vtkDistanceWidget. Take a look what I have tried: void CVT…

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## [Pick a widget](https://discourse.vtk.org/t/pick-a-widget/2573)

<div class="topic-metadata">

**Author:** [@flaviu2](https://discourse.vtk.org/u/flaviu2)\
**Replies:** 17\
**Last updated:** [February 19, 2020, 11:50am UTC](https://discourse.vtk.org/t/pick-a-widget/2573 "2020-02-19T11:50:22Z")

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I am struggle for a while to achieve something simple: to pick a widget (a distance widget) with mouse pointer, in order to modify it or delete it. Here is my trial: vtkPropPicker\* pPicker = vtkPropPicker::New(); pPi…

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## [From vtkDistanceRepresentation2D to vtkDistanceWidget](https://discourse.vtk.org/t/from-vtkdistancerepresentation2d-to-vtkdistancewidget/2646)

<div class="topic-metadata">

**Author:** [@flaviu2](https://discourse.vtk.org/u/flaviu2)\
**Replies:** 1\
**Last updated:** [February 19, 2020, 10:17am UTC](https://discourse.vtk.org/t/from-vtkdistancerepresentation2d-to-vtkdistancewidget/2646 "2020-02-19T10:17:18Z")

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If I got a pointer to vtkDistanceRepresentation2D (through a picker), how can I get a pointer to my vtkDistanceWidget which contain this vtkDistanceRepresentation2D ?

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## [Anti-aliasing / multi sampling with vtkGenericOpenGLRenderWindow](https://discourse.vtk.org/t/anti-aliasing-multi-sampling-with-vtkgenericopenglrenderwindow/2463)

<div class="topic-metadata">

**Author:** [@michael23](https://discourse.vtk.org/u/michael23)\
**Replies:** 1\
**Last updated:** [February 18, 2020, 2:22pm UTC](https://discourse.vtk.org/t/anti-aliasing-multi-sampling-with-vtkgenericopenglrenderwindow/2463 "2020-02-18T14:22:36Z")

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Hello, I am using vtkGenericOpenGLRenderWindow and QVTKOpenGLNativeWidget for VTK rendering in Qt. In order to get the right result when using the vtkSelectVisiblePoints filter, I had to set the number of multi samples…

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## [Custom user interface](https://discourse.vtk.org/t/custom-user-interface/2623)

<div class="topic-metadata">

**Author:** [@Tracy\_Nk](https://discourse.vtk.org/u/Tracy_Nk)\
**Replies:** 2\
**Last updated:** [February 17, 2020, 11:46am UTC](https://discourse.vtk.org/t/custom-user-interface/2623 "2020-02-17T11:46:42Z")

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I apologise as i’m quite new to VTK Is it possible to create my own user interface (with buttons etc) via C++ to display the volume rendered model? through researching, I’ve seen a lot of people mentioning QT, if that’s…

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## [invalid array name](https://discourse.vtk.org/t/invalid-array-name/2605)

<div class="topic-metadata">

**Author:** [@hao\_hu](https://discourse.vtk.org/u/hao_hu)\
**Replies:** 2\
**Last updated:** [February 17, 2020, 11:19am UTC](https://discourse.vtk.org/t/invalid-array-name/2605 "2020-02-17T11:19:31Z")

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I write calculator = vtk.vtkArrayCalculator() calculator.SetInputConnection(cellToPoint.GetOutputPort()) calculator.SetAttributeType(vtk.vtkDataObject.POINT ) print(calculator.GetNumberOfScalarAr…

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## [Unable to render image](https://discourse.vtk.org/t/unable-to-render-image/2598)

<div class="topic-metadata">

**Author:** [@Tracy\_Nk](https://discourse.vtk.org/u/Tracy_Nk)\
**Replies:** 2\
**Last updated:** [February 17, 2020, 11:10am UTC](https://discourse.vtk.org/t/unable-to-render-image/2598 "2020-02-17T11:10:14Z")

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Here is an example code i’m using: #include vtkSmartPointer.h #include vtkDataArray.h #include vtkImageData.h #include vtkImageViewer2.h #include vtkDICOMImageReader.h #include vtkPointData.h #include vtkRenderWin…

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## [vtkContourWidget show no lines](https://discourse.vtk.org/t/vtkcontourwidget-show-no-lines/2640)

<div class="topic-metadata">

**Author:** [@snow](https://discourse.vtk.org/u/snow)\
**Replies:** 0\
**Last updated:** [February 17, 2020, 9:23am UTC](https://discourse.vtk.org/t/vtkcontourwidget-show-no-lines/2640 "2020-02-17T09:23:55Z")

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I’m vtk beginner , i have problems when i used vtkContourWidget with vtkOrientedGlyphFocalPlaneContourRepresentation . I want to create a contour on the screen coordinate, not world coordinate. so I write some code ,…

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## [How to read .vtk structured grid format in Vtk.js?](https://discourse.vtk.org/t/how-to-read-vtk-structured-grid-format-in-vtk-js/2634)

<div class="topic-metadata">

**Author:** [@Chibipaper](https://discourse.vtk.org/u/Chibipaper)\
**Replies:** 0\
**Last updated:** [February 17, 2020, 2:43am UTC](https://discourse.vtk.org/t/how-to-read-vtk-structured-grid-format-in-vtk-js/2634 "2020-02-17T02:43:49Z")

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Hello, I am trying to build a web application that can visualize 3D images using the vtk.js library. I have been following the vtk.js tutorials and I found this library very promising but I am currently stuck on the fol…

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## [vtkTransform::Concatenate() is very slow](https://discourse.vtk.org/t/vtktransform-concatenate-is-very-slow/2637)

<div class="topic-metadata">

**Author:** [@mmm](https://discourse.vtk.org/u/mmm)\
**Replies:** 0\
**Last updated:** [February 17, 2020, 7:24am UTC](https://discourse.vtk.org/t/vtktransform-concatenate-is-very-slow/2637 "2020-02-17T07:24:18Z")

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vtkTransform::Concatenate() gets very slow after calling it multiple times. The situation is the following: I call vtkTransform::Concatenate( anotherTransform ) to concatenate another vtkTransform (basically applying…

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## [Parallel Rendering with VTK](https://discourse.vtk.org/t/parallel-rendering-with-vtk/2628)

<div class="topic-metadata">

**Author:** [@guten-tag](https://discourse.vtk.org/u/guten-tag)\
**Replies:** 0\
**Last updated:** [February 16, 2020, 9:07am UTC](https://discourse.vtk.org/t/parallel-rendering-with-vtk/2628 "2020-02-16T09:07:27Z")

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Hi, Community, Recently I have just begun to do some research about parallel rendering with VTK. It’s so wonderful that VTK has provided many interfaces for user to call for. However it’s wired that I just could find vt…

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## [Python 3.8 wrapping support?](https://discourse.vtk.org/t/python-3-8-wrapping-support/2621)

<div class="topic-metadata">

**Author:** [@aborsic](https://discourse.vtk.org/u/aborsic)\
**Replies:** 6\
**Last updated:** [February 15, 2020, 10:33pm UTC](https://discourse.vtk.org/t/python-3-8-wrapping-support/2621 "2020-02-15T22:33:22Z")

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Hi, I am trying to compile VTK 8.2.0 on Windows 10 64bit, Python 3.8.1 64bit, Visual Studio 2015 Update 3. A simple CMake configuration that has worked well with VTK 8.1.2 and Python 3.6 is now throwing hundreds of err…

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## [Glyphs errors when moving a QVTKOpenGLWidget to an another layout](https://discourse.vtk.org/t/glyphs-errors-when-moving-a-qvtkopenglwidget-to-an-another-layout/2581)

<div class="topic-metadata">

**Author:** [@embeddedmz](https://discourse.vtk.org/u/embeddedmz)\
**Replies:** 7\
**Last updated:** [February 14, 2020, 2:42pm UTC](https://discourse.vtk.org/t/glyphs-errors-when-moving-a-qvtkopenglwidget-to-an-another-layout/2581 "2020-02-14T14:42:11Z")

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Hi, I’m getting these errors when I’m moving the QVTKOpenGLWidget, in which I’m using a vtkGlyph3DMapper, to an another layout of another widget in order to show it full screen : ERROR: In /home/febus-g1/rpmbuild/BUIL…

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## [vtkDataSet.SafeDownCast probleam](https://discourse.vtk.org/t/vtkdataset-safedowncast-probleam/2580)

<div class="topic-metadata">

**Author:** [@hao\_hu](https://discourse.vtk.org/u/hao_hu)\
**Replies:** 2\
**Last updated:** [February 14, 2020, 12:29pm UTC](https://discourse.vtk.org/t/vtkdataset-safedowncast-probleam/2580 "2020-02-14T12:29:40Z")

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I wrote a statement ds = vtk.vtkDataSet.SafeDownCast(reader.GetOutput().GetBlock(i)) in python. I want to convert this data to vtkDataSet type but the converted ds is NoneType. I don’t know what went wrong, can anyone te…

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## [vtkInteractionStyle was not found](https://discourse.vtk.org/t/vtkinteractionstyle-was-not-found/2611)

<div class="topic-metadata">

**Author:** [@siaeleni](https://discourse.vtk.org/u/siaeleni)\
**Replies:** 1\
**Last updated:** [February 13, 2020, 8:36pm UTC](https://discourse.vtk.org/t/vtkinteractionstyle-was-not-found/2611 "2020-02-13T20:36:30Z")

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I have configured vtk, qt and itk using VS 2017 on Windows. (VTK 8.2, Qt 5.14.1 ) Now I want to try a very simple example with the Sphere https://lorensen.github.io/VTKExamples/site/Cxx/GeometricObjects/Sphere/ but I ge…

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## [VTK-4.4.2 Building Problem](https://discourse.vtk.org/t/vtk-4-4-2-building-problem/2614)

<div class="topic-metadata">

**Author:** [@Arda\_Goktogan](https://discourse.vtk.org/u/Arda_Goktogan)\
**Replies:** 1\
**Last updated:** [February 13, 2020, 8:33pm UTC](https://discourse.vtk.org/t/vtk-4-4-2-building-problem/2614 "2020-02-13T20:33:05Z")

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Hi, I’m trying to build VTK-4.4.2 From its source code. When I run make it gives the following error: /home/ardofski/vtk-v4.4.1/Utilities/DICOMParser/DICOMFile.cxx:58:47: error: 'strcmp' was not declared in this sc…

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## [Writing polyData as structured .VTK Imagedata](https://discourse.vtk.org/t/writing-polydata-as-structured-vtk-imagedata/2608)

<div class="topic-metadata">

**Author:** [@ShaneKirkbride](https://discourse.vtk.org/u/ShaneKirkbride)\
**Replies:** 3\
**Last updated:** [February 13, 2020, 7:50pm UTC](https://discourse.vtk.org/t/writing-polydata-as-structured-vtk-imagedata/2608 "2020-02-13T19:50:28Z")

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I can write polyData to a .vtk file but it is an unstructured blob. I need a header to preserve my geometry of my object (I want to read it into an ITK registration application). I saw the example on PolyData to ImageDa…

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## [How to check disconnected vertices in a triangular mesh](https://discourse.vtk.org/t/how-to-check-disconnected-vertices-in-a-triangular-mesh/2593)

<div class="topic-metadata">

**Author:** [@srbn.ghosh99](https://discourse.vtk.org/u/srbn.ghosh99)\
**Replies:** 3\
**Last updated:** [February 13, 2020, 7:31pm UTC](https://discourse.vtk.org/t/how-to-check-disconnected-vertices-in-a-triangular-mesh/2593 "2020-02-13T19:31:00Z")

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Hello Everyone, I have a triangular mesh that has 1038458 polygons, 517817 points, 1557687 edges. During the simplification process, I am getting the message that there are 1092 disconnected vertices, 516725 connected v…

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## [Draw an actor as 2D overlay using normalized viewport coordinates](https://discourse.vtk.org/t/draw-an-actor-as-2d-overlay-using-normalized-viewport-coordinates/2610)

<div class="topic-metadata">

**Author:** [@michael23](https://discourse.vtk.org/u/michael23)\
**Replies:** 0\
**Last updated:** [February 13, 2020, 3:49pm UTC](https://discourse.vtk.org/t/draw-an-actor-as-2d-overlay-using-normalized-viewport-coordinates/2610 "2020-02-13T15:49:07Z")

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Hello, I created a 3D scene with some spheres close to a surface. Furthermore I want to render spheres which are not related to the surface. I already tried to place the additional spheres next to the surface but that’s…

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## [How to correctly use vtkPixelBufferObject](https://discourse.vtk.org/t/how-to-correctly-use-vtkpixelbufferobject/2609)

<div class="topic-metadata">

**Author:** [@Seun](https://discourse.vtk.org/u/Seun)\
**Replies:** 0\
**Last updated:** [February 13, 2020, 3:22pm UTC](https://discourse.vtk.org/t/how-to-correctly-use-vtkpixelbufferobject/2609 "2020-02-13T15:22:04Z")

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Hi everyone, I have recently been looking into using vtkPixelBufferObject to perform basic PBO, bind capture data update unbind here’s what I’ve done thus far (if I’m correct) a render window to be set as its cont…

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## [Filling a OpenGLVertexBufferObject with a custom DataArray](https://discourse.vtk.org/t/filling-a-openglvertexbufferobject-with-a-custom-dataarray/2548)

<div class="topic-metadata">

**Author:** [@BotellaA](https://discourse.vtk.org/u/BotellaA)\
**Replies:** 2\
**Last updated:** [February 13, 2020, 1:27pm UTC](https://discourse.vtk.org/t/filling-a-openglvertexbufferobject-with-a-custom-dataarray/2548 "2020-02-13T13:27:35Z")

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Hello! I am trying to provide a custom C++ object to a PolyData by overriding its DataArray. For example, I would like to give a custom DataArray (made of a struct of double) to the PolyData Points. I have an issue whe…

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## [VTK 9 release coming](https://discourse.vtk.org/t/vtk-9-release-coming/1859)

<div class="topic-metadata">

**Author:** [@Dave\_DeMarle](https://discourse.vtk.org/u/Dave_DeMarle)\
**Replies:** 13\
**Last updated:** [February 13, 2020, 7:26am UTC](https://discourse.vtk.org/t/vtk-9-release-coming/1859 "2020-02-13T07:26:32Z")

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Hey Folks, I would like to start up the release process for VTK 9.0. @ben.boeckel and I both think that we need to tie up these loose ends before making the branch. write the VTK 9 transition guide (documenting things…

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## [Controlled Surface Triangulation](https://discourse.vtk.org/t/controlled-surface-triangulation/2526)

<div class="topic-metadata">

**Author:** [@ChristopherWaters](https://discourse.vtk.org/u/ChristopherWaters)\
**Replies:** 12\
**Last updated:** [February 13, 2020, 6:03am UTC](https://discourse.vtk.org/t/controlled-surface-triangulation/2526 "2020-02-13T06:03:06Z")

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Currently: I have a VTK program that allows you to build and edit meshes. What I Want to Achieve: I would like to apply triangulation to the surfaces of the meshes for FEM (meshes are unstructured grids) Have the …

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## [Plotting 2D Isosurface in Python](https://discourse.vtk.org/t/plotting-2d-isosurface-in-python/2577)

<div class="topic-metadata">

**Author:** [@RSwn](https://discourse.vtk.org/u/RSwn)\
**Replies:** 2\
**Last updated:** [February 12, 2020, 8:13pm UTC](https://discourse.vtk.org/t/plotting-2d-isosurface-in-python/2577 "2020-02-12T20:13:23Z")

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I am looking to plot a 2D isosurface using VTK in Python. I am trying to visualise the Q-Criterion in Paraview but am looking to build the isosurface into the file rather than using the Paraview option. I couldn’t find m…

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## [Changing the Scalar Values of a vtkImageReslice Object in a Pipeline](https://discourse.vtk.org/t/changing-the-scalar-values-of-a-vtkimagereslice-object-in-a-pipeline/2584)

<div class="topic-metadata">

**Author:** [@MichelleKline](https://discourse.vtk.org/u/MichelleKline)\
**Replies:** 2\
**Last updated:** [February 12, 2020, 3:36pm UTC](https://discourse.vtk.org/t/changing-the-scalar-values-of-a-vtkimagereslice-object-in-a-pipeline/2584 "2020-02-12T15:36:27Z")

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Hello, I am using vtkImageReslice to reslice a volume. I do the reslicing by controlling the resliceAxes of the vtkImageReslice object. Each time a “take a new slice” (ie, change the resliceAxes), I perform some calcu…

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## [I can't find QVTKOpenGLWidget in VTK 7.1.1](https://discourse.vtk.org/t/i-cant-find-qvtkopenglwidget-in-vtk-7-1-1/2589)

<div class="topic-metadata">

**Author:** [@embeddedmz](https://discourse.vtk.org/u/embeddedmz)\
**Replies:** 0\
**Last updated:** [February 12, 2020, 12:13pm UTC](https://discourse.vtk.org/t/i-cant-find-qvtkopenglwidget-in-vtk-7-1-1/2589 "2020-02-12T12:13:54Z")

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Hi VTK Experts, The title says it all : I can’t find QVTKOpenGLWidget in VTK 7.1.1 sources. Is that normal ? Thanks !

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## [Vertical stripe for some Sample Distance values](https://discourse.vtk.org/t/vertical-stripe-for-some-sample-distance-values/2574)

<div class="topic-metadata">

**Author:** [@Ana\_Margarida\_Mota](https://discourse.vtk.org/u/Ana_Margarida_Mota)\
**Replies:** 6\
**Last updated:** [February 12, 2020, 11:44am UTC](https://discourse.vtk.org/t/vertical-stripe-for-some-sample-distance-values/2574 "2020-02-12T11:44:27Z")

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Dear colleagues, I am facing a problem when changing the sample distance value. For certain values of sample distance, defined with SetSampleDistance (), a vertical stripe that crosses the entire object appears when I …

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## [Looking for answer to this vtkImageReslice question](https://discourse.vtk.org/t/looking-for-answer-to-this-vtkimagereslice-question/2588)

<div class="topic-metadata">

**Author:** [@richardander](https://discourse.vtk.org/u/richardander)\
**Replies:** 1\
**Last updated:** [February 12, 2020, 8:46am UTC](https://discourse.vtk.org/t/looking-for-answer-to-this-vtkimagereslice-question/2588 "2020-02-12T08:46:25Z")

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Can any one help with this question? Thank you!

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## [How do I modify the selection box in vtkInteractor StyleRubberBandPick to a selection circle?](https://discourse.vtk.org/t/how-do-i-modify-the-selection-box-in-vtkinteractor-stylerubberbandpick-to-a-selection-circle/2586)

<div class="topic-metadata">

**Author:** [@ymmx](https://discourse.vtk.org/u/ymmx)\
**Replies:** 0\
**Last updated:** [February 12, 2020, 7:48am UTC](https://discourse.vtk.org/t/how-do-i-modify-the-selection-box-in-vtkinteractor-stylerubberbandpick-to-a-selection-circle/2586 "2020-02-12T07:48:29Z")

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I’m wondering if it is possible to modify the shape of the box that is displayed when I pick an area with ‘r’? I would like it to be circle where the center is the position the mouse was at when I pressed the mouse and t…

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## [How can I add a observer to a vtk Interactor Style Rubber Band Pick class?](https://discourse.vtk.org/t/how-can-i-add-a-observer-to-a-vtk-interactor-style-rubber-band-pick-class/2532)

<div class="topic-metadata">

**Author:** [@ymmx](https://discourse.vtk.org/u/ymmx)\
**Replies:** 4\
**Last updated:** [February 12, 2020, 7:39am UTC](https://discourse.vtk.org/t/how-can-i-add-a-observer-to-a-vtk-interactor-style-rubber-band-pick-class/2532 "2020-02-12T07:39:04Z")

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I’m trying to add an Observer to a class that inherit from vtkInteractorStyleRubberBandPick. My goal is to trigger a function when I finished to make a bouding box on the screen with the key ‘r’. The issue is I don’t f…

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