# Latest

**URL:** https://discourse.vtk.org/latest.md?page=255

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

**Page:** 256

---

## [demystifiying color discretization](https://discourse.vtk.org/t/demystifiying-color-discretization/117)

<div class="topic-metadata">

**Author:** [@embeddedmz](https://discourse.vtk.org/u/embeddedmz)\
**Replies:** 11\
**Last updated:** [March 14, 2019, 2:57pm UTC](https://discourse.vtk.org/t/demystifiying-color-discretization/117 "2019-03-14T14:57:18Z")

</div>

Hi, In the past, I had a slow rendering problem. At the time, the problem was color management with ‘vtkColorTransferFunction’. I solved the problem by using a ‘vtkLookupTable’ along with the ‘vtkColorTransferFunction’…

---

## [MultiBlockDataSet field data inaccessible from outer layer](https://discourse.vtk.org/t/multiblockdataset-field-data-inaccessible-from-outer-layer/482)

<div class="topic-metadata">

**Author:** [@phil\_ossk](https://discourse.vtk.org/u/phil_ossk)\
**Replies:** 2\
**Last updated:** [March 14, 2019, 1:51pm UTC](https://discourse.vtk.org/t/multiblockdataset-field-data-inaccessible-from-outer-layer/482 "2019-03-14T13:51:44Z")

</div>

Hello there, Before submitting a bug report, I am looking for your input on an issue I am facing. I have a MultiBlockDataSet (let’s call it mbds0) with several blocks . Some field data (testArray0 and testArray1) has b…

---

## [Changing stereo-related flags](https://discourse.vtk.org/t/changing-stereo-related-flags/477)

<div class="topic-metadata">

**Author:** [@utkarshayachit](https://discourse.vtk.org/u/utkarshayachit)\
**Replies:** 3\
**Last updated:** [March 14, 2019, 10:59am UTC](https://discourse.vtk.org/t/changing-stereo-related-flags/477 "2019-03-14T10:59:15Z")

</div>

Currently there are 3 user-settable flags that affect whether and how vtkRenderWindow does stereo rendering: StereoCapableWindow, StereoRender and StereoType. All are user settable and the biggest annoyance is that there…

---

## [vtkSplineWidget(2) vtkMarchingSquares and vtkImageData](https://discourse.vtk.org/t/vtksplinewidget-2-vtkmarchingsquares-and-vtkimagedata/464)

<div class="topic-metadata">

**Author:** [@Romain](https://discourse.vtk.org/u/Romain)\
**Replies:** 1\
**Last updated:** [March 14, 2019, 8:22am UTC](https://discourse.vtk.org/t/vtksplinewidget-2-vtkmarchingsquares-and-vtkimagedata/464 "2019-03-14T08:22:58Z")

</div>

Hello everyone, I’m working with vtk 8.2 on Windows 10 with VS 2017. I try to create a closed Spline around the contour of a binary image in purpose to change the value of each pixels inside the closed spline. To do t…

---

## [Having a dedicated tag for fileformats](https://discourse.vtk.org/t/having-a-dedicated-tag-for-fileformats/471)

<div class="topic-metadata">

**Author:** [@vrkssai](https://discourse.vtk.org/u/vrkssai)\
**Replies:** 2\
**Last updated:** [March 14, 2019, 3:28am UTC](https://discourse.vtk.org/t/having-a-dedicated-tag-for-fileformats/471 "2019-03-14T03:28:53Z")

</div>

I think it would be in the best of interests of the community if we had an optional tag for File Format related questions. It would help reaching out to the community better, for answers.

---

## [Logging error messages for empty input data](https://discourse.vtk.org/t/logging-error-messages-for-empty-input-data/453)

<div class="topic-metadata">

**Author:** [@lassoan](https://discourse.vtk.org/u/lassoan)\
**Replies:** 3\
**Last updated:** [March 13, 2019, 9:30pm UTC](https://discourse.vtk.org/t/logging-error-messages-for-empty-input-data/453 "2019-03-13T21:30:47Z")

</div>

Some filters, such as vtkTransformPolyDataFilter, logs lots of No input data messages when the input polydata happens to be empty. These messages clutter the application log and causes significant performance drop. To a…

---

## [Convert VTI File to Numpy Array in Python Programming](https://discourse.vtk.org/t/convert-vti-file-to-numpy-array-in-python-programming/459)

<div class="topic-metadata">

**Author:** [@qmaaj](https://discourse.vtk.org/u/qmaaj)\
**Replies:** 2\
**Last updated:** [March 13, 2019, 7:50pm UTC](https://discourse.vtk.org/t/convert-vti-file-to-numpy-array-in-python-programming/459 "2019-03-13T19:50:03Z")

</div>

Suppose I have a vti file containing a scalar field (such as velocity) and its corresponding spatial coordinates (x, y, z coordinates), how should I read the vti file using Python programming and convert the vtil file to…

---

## [Update of WIKI on building VTK in visual studio](https://discourse.vtk.org/t/update-of-wiki-on-building-vtk-in-visual-studio/429)

<div class="topic-metadata">

**Author:** [@rdbrn](https://discourse.vtk.org/u/rdbrn)\
**Replies:** 5\
**Last updated:** [March 13, 2019, 2:11pm UTC](https://discourse.vtk.org/t/update-of-wiki-on-building-vtk-in-visual-studio/429 "2019-03-13T14:11:47Z")

</div>

Hi there, I just went through the wiki (https://vtk.org/Wiki/VTK/Building/Windows) on building VTK on windows using visual studio. I had quite some trouble getting it all to work. Especially as the last step (install) r…

---

## [Vtk.js: Convert the selection point into world coordinates](https://discourse.vtk.org/t/vtk-js-convert-the-selection-point-into-world-coordinates/473)

<div class="topic-metadata">

**Author:** [@qingchen](https://discourse.vtk.org/u/qingchen)\
**Replies:** 1\
**Last updated:** [March 13, 2019, 4:26am UTC](https://discourse.vtk.org/t/vtk-js-convert-the-selection-point-into-world-coordinates/473 "2019-03-13T04:26:52Z")

</div>

Hello, I used example GeometryViewer to load a VTP file and selected a point using PointPicker , this point is sometimes marked on the back of the selected point. But I want to return the closest point to the surface of…

---

## ["How to render the pixel contour of an image" Follow-Up](https://discourse.vtk.org/t/how-to-render-the-pixel-contour-of-an-image-follow-up/463)

<div class="topic-metadata">

**Author:** [@Harry](https://discourse.vtk.org/u/Harry)\
**Replies:** 3\
**Last updated:** [March 13, 2019, 12:02am UTC](https://discourse.vtk.org/t/how-to-render-the-pixel-contour-of-an-image-follow-up/463 "2019-03-13T00:02:54Z")

</div>

I have a follow-up question to this thread: https://public.kitware.com/pipermail/vtkusers/2011-June/068268.html I have the same problem that his example pictures demonstrate well - I want to render the edges of the “ins…

---

## [Coverage still missing](https://discourse.vtk.org/t/coverage-still-missing/447)

<div class="topic-metadata">

**Author:** [@lorensen](https://discourse.vtk.org/u/lorensen)\
**Replies:** 4\
**Last updated:** [March 12, 2019, 8:53pm UTC](https://discourse.vtk.org/t/coverage-still-missing/447 "2019-03-12T20:53:17Z")

</div>

The coverage machine has a config error. Could someone please fix it? Could NOT find OpenVR (missing: OpenVR\_LIBRARY OpenVR\_INCLUDE\_DIR) CMake Error at CMake/vtkModule.cmake:3524 (message): Could not find the OpenVR e…

---

## [How to create ResliceAxes from two points in vtkImageReslice](https://discourse.vtk.org/t/how-to-create-resliceaxes-from-two-points-in-vtkimagereslice/466)

<div class="topic-metadata">

**Author:** [@richardander](https://discourse.vtk.org/u/richardander)\
**Replies:** 0\
**Last updated:** [March 12, 2019, 7:26pm UTC](https://discourse.vtk.org/t/how-to-create-resliceaxes-from-two-points-in-vtkimagereslice/466 "2019-03-12T19:26:07Z")

</div>

I would like to use vtkImageReslice to get the cross section of a curve at a point P0. To compute the reslixeAxes, I would like to use P0 and its neighboring point P1 to decisde the direction. As you know, resliceAxes …

---

## [Doxygen not working since new module API](https://discourse.vtk.org/t/doxygen-not-working-since-new-module-api/446)

<div class="topic-metadata">

**Author:** [@lorensen](https://discourse.vtk.org/u/lorensen)\
**Replies:** 1\
**Last updated:** [March 12, 2019, 2:24pm UTC](https://discourse.vtk.org/t/doxygen-not-working-since-new-module-api/446 "2019-03-12T14:24:21Z")

</div>

Folks, I’m pretty sure doxygen is broken since the recent module API changes. Can someone verify this? Bill

---

## [world coordinates do not give the correct dicom coordinate](https://discourse.vtk.org/t/world-coordinates-do-not-give-the-correct-dicom-coordinate/452)

<div class="topic-metadata">

**Author:** [@zandarina](https://discourse.vtk.org/u/zandarina)\
**Replies:** 0\
**Last updated:** [March 11, 2019, 5:25pm UTC](https://discourse.vtk.org/t/world-coordinates-do-not-give-the-correct-dicom-coordinate/452 "2019-03-11T17:25:11Z")

</div>

Dear all, I want to do segmentation with itk and i would like to select a seed using vtk with the mouse. I get the coordinates in world coordinates int x = this-\>Interactor-\>GetEventPosition()\[0\]; …

---

## [vtkPlotSurface status](https://discourse.vtk.org/t/vtkplotsurface-status/426)

<div class="topic-metadata">

**Author:** [@infinnovation-dev](https://discourse.vtk.org/u/infinnovation-dev)\
**Replies:** 2\
**Last updated:** [March 11, 2019, 1:07pm UTC](https://discourse.vtk.org/t/vtkplotsurface-status/426 "2019-03-11T13:07:33Z")

</div>

I came across VTK when looking for an easy way to view data from a data acquisition system I’m writing. Plus points were python bindings, interaction capability, and that it is already packaged for both Ubuntu/Debian a…

---

## [How to improve vtkDICOMImageReader output](https://discourse.vtk.org/t/how-to-improve-vtkdicomimagereader-output/430)

<div class="topic-metadata">

**Author:** [@Michele](https://discourse.vtk.org/u/Michele)\
**Replies:** 8\
**Last updated:** [March 11, 2019, 9:34am UTC](https://discourse.vtk.org/t/how-to-improve-vtkdicomimagereader-output/430 "2019-03-11T09:34:48Z")

</div>

Hi everyone, I am VTK user and recently I needed to start visualizing some DICOM in the 3D space. The idea is to shows some stl from segmentation together with some relative DICOM. Essentially, I follow the vtkDICOMImag…

---

## [World coordinate do not give me the correct dicom coordinate](https://discourse.vtk.org/t/world-coordinate-do-not-give-me-the-correct-dicom-coordinate/440)

<div class="topic-metadata">

**Author:** [@zandarina](https://discourse.vtk.org/u/zandarina)\
**Replies:** 0\
**Last updated:** [March 11, 2019, 2:41am UTC](https://discourse.vtk.org/t/world-coordinate-do-not-give-me-the-correct-dicom-coordinate/440 "2019-03-11T02:41:08Z")

</div>

Dear all, I use itk to perform 2d segmentation of a 3d volume given by a dicom series and i need to add some seeds with the mouse for some 2d slices. So i am forced to show a 2d slice in vtk obtained with itk (using e…

---

## [vtkImageData.ToBitmap() produces uncompatible bitmaps](https://discourse.vtk.org/t/vtkimagedata-tobitmap-produces-uncompatible-bitmaps/435)

<div class="topic-metadata">

**Author:** [@pettaa123](https://discourse.vtk.org/u/pettaa123)\
**Replies:** 1\
**Last updated:** [March 8, 2019, 9:22pm UTC](https://discourse.vtk.org/t/vtkimagedata-tobitmap-produces-uncompatible-bitmaps/435 "2019-03-08T21:22:45Z")

</div>

Hi, I love VTK but im kind of struggling right now: double\[\] viewport=viewportRenderer.GetViewport(); vtkWindowToImageFilter imageFilter = vtkWindowToImageFilter.New(); imageFilter.SetInput(Rende…

---

## [Segmentation of objects in a point cloud (Python)](https://discourse.vtk.org/t/segmentation-of-objects-in-a-point-cloud-python/273)

<div class="topic-metadata">

**Author:** [@jball](https://discourse.vtk.org/u/jball)\
**Replies:** 9\
**Last updated:** [March 8, 2019, 11:18am UTC](https://discourse.vtk.org/t/segmentation-of-objects-in-a-point-cloud-python/273 "2019-03-08T11:18:46Z")

</div>

Hi all, I was wondering if anyone would be able to help me. I have a series of different point clouds (.ply files) of different fields containing crop plots. I’ve generated this using Pix4D. These field have a natural …

---

## [Possible bug on vtkPolyDataConnectivityFilter](https://discourse.vtk.org/t/possible-bug-on-vtkpolydataconnectivityfilter/413)

<div class="topic-metadata">

**Author:** [@kojikoby](https://discourse.vtk.org/u/kojikoby)\
**Replies:** 9\
**Last updated:** [March 8, 2019, 12:18am UTC](https://discourse.vtk.org/t/possible-bug-on-vtkpolydataconnectivityfilter/413 "2019-03-08T00:18:50Z")

</div>

Hi, I am using VTK for medical applications, and encounter a possible bug on vtkPolyConnectivityFilter. I use the function to generate an STL from only the largest connected region. I doubt the spacing parameter of VTK …

---

## [Doxygen pages](https://discourse.vtk.org/t/doxygen-pages/337)

<div class="topic-metadata">

**Author:** [@tirons](https://discourse.vtk.org/u/tirons)\
**Replies:** 5\
**Last updated:** [March 7, 2019, 4:59pm UTC](https://discourse.vtk.org/t/doxygen-pages/337 "2019-03-07T16:59:26Z")

</div>

From https://vtk.org/documentation/ the only links for the Doxygen files are for the nightly builds. Are the stable versions of documentation still hosted somewhere?

---

## [2D Polygon Boolean Operations](https://discourse.vtk.org/t/2d-polygon-boolean-operations/283)

<div class="topic-metadata">

**Author:** [@Harry](https://discourse.vtk.org/u/Harry)\
**Replies:** 8\
**Last updated:** [March 7, 2019, 5:51am UTC](https://discourse.vtk.org/t/2d-polygon-boolean-operations/283 "2019-03-07T05:51:10Z")

</div>

Hi all, I have what I think should be an extremely easy problem, but I can’t figure out how to do it. I have two coplanar polygons generated from vtkContourWidget and stored as vtkPolyData, and I want to be able to perf…

---

## [Move a scalar bar with pyq5 and python3.5](https://discourse.vtk.org/t/move-a-scalar-bar-with-pyq5-and-python3-5/289)

<div class="topic-metadata">

**Author:** [@guillaume](https://discourse.vtk.org/u/guillaume)\
**Replies:** 7\
**Last updated:** [March 6, 2019, 7:35pm UTC](https://discourse.vtk.org/t/move-a-scalar-bar-with-pyq5-and-python3-5/289 "2019-03-06T19:35:45Z")

</div>

Hi all, I’m trying write an application with a vtk windows. Nevertheless, I have some difficulties to move and resize manually the scalar bar when I use pyqt5. Here’s my code: # -\*- coding: utf-8 -\*- import sys from…

---

## [Checking if actor is visible to a user](https://discourse.vtk.org/t/checking-if-actor-is-visible-to-a-user/357)

<div class="topic-metadata">

**Author:** [@marf](https://discourse.vtk.org/u/marf)\
**Replies:** 4\
**Last updated:** [March 6, 2019, 1:21pm UTC](https://discourse.vtk.org/t/checking-if-actor-is-visible-to-a-user/357 "2019-03-06T13:21:54Z")

</div>

Hello, I try to check if an Actor can be seen by a user or if it is hidden behind another object. Currently I try doing this with a picker, since I thought it would only select the topmost Actor. But it selects all acto…

---

## [Get 2D bounds of an actor](https://discourse.vtk.org/t/get-2d-bounds-of-an-actor/408)

<div class="topic-metadata">

**Author:** [@marf](https://discourse.vtk.org/u/marf)\
**Replies:** 2\
**Last updated:** [March 6, 2019, 11:23am UTC](https://discourse.vtk.org/t/get-2d-bounds-of-an-actor/408 "2019-03-06T11:23:41Z")

</div>

Hello, I’m trying to figure out the “on-screen” bounds of an actor. Right now, I get the actors 3D bounds and transform them into screen coordinates with the vtkCoordinate. The obtained position is somewhat ok. But when…

---

## [Invalid framebuffer operation](https://discourse.vtk.org/t/invalid-framebuffer-operation/403)

<div class="topic-metadata">

**Author:** [@hmxhiu](https://discourse.vtk.org/u/hmxhiu)\
**Replies:** 1\
**Last updated:** [March 6, 2019, 2:44am UTC](https://discourse.vtk.org/t/invalid-framebuffer-operation/403 "2019-03-06T02:44:01Z")

</div>

Hi all, I’m currently having the following error while running VTK8.2 on the new Mac Mini 2018: ERROR: /VTK-8.2.0/Rendering/OpenGL2/vtkOpenGLImageSliceMapper.cxx, line 485 vtkOpenGLImageSliceMapper: failed after Rend…

---

## [overlay/transparency issue with QVTKOpenGLNativeWidget](https://discourse.vtk.org/t/overlay-transparency-issue-with-qvtkopenglnativewidget/196)

<div class="topic-metadata">

**Author:** [@mikewho](https://discourse.vtk.org/u/mikewho)\
**Replies:** 7\
**Last updated:** [March 5, 2019, 8:20pm UTC](https://discourse.vtk.org/t/overlay-transparency-issue-with-qvtkopenglnativewidget/196 "2019-03-05T20:20:33Z")

</div>

I had previously been using QVTKWidget in VTK 7.1.0 with no issues. I decided to upgrade to VTK 8.2.0 and try out QVTKOpenGLNativeWidget. However I am noticing that with the new widget when I overlay two vtkImageActors, …

---

## [Extracting boundary nodes from an unstructured grid](https://discourse.vtk.org/t/extracting-boundary-nodes-from-an-unstructured-grid/406)

<div class="topic-metadata">

**Author:** [@Zoltan\_Kovacs](https://discourse.vtk.org/u/Zoltan_Kovacs)\
**Replies:** 0\
**Last updated:** [March 5, 2019, 2:11pm UTC](https://discourse.vtk.org/t/extracting-boundary-nodes-from-an-unstructured-grid/406 "2019-03-05T14:11:50Z")

</div>

Dear all, I try to extract the boundary nodes of an unstructured grids. Based on the example https://vtk.org/Wiki/VTK/Examples/Cxx/Meshes/BoundaryEdges I used the following code: vtkSmartPointer grid = vtkSmartPointe…

---

## [How to check if rendering is done/ready](https://discourse.vtk.org/t/how-to-check-if-rendering-is-done-ready/399)

<div class="topic-metadata">

**Author:** [@mikewho](https://discourse.vtk.org/u/mikewho)\
**Replies:** 2\
**Last updated:** [March 5, 2019, 12:15pm UTC](https://discourse.vtk.org/t/how-to-check-if-rendering-is-done-ready/399 "2019-03-05T12:15:56Z")

</div>

Is there a way to check if rendering is done/ready (vtkRenderer & vtkRenderWindow)? I’m calling Render very frequently, and the GPU basically falls behind a bit which introduces a lag. What I’d like to do is have an if s…

---

## [VTK6.3 & Qt5 building issue](https://discourse.vtk.org/t/vtk6-3-qt5-building-issue/400)

<div class="topic-metadata">

**Author:** [@Massi](https://discourse.vtk.org/u/Massi)\
**Replies:** 1\
**Last updated:** [March 5, 2019, 4:07am UTC](https://discourse.vtk.org/t/vtk6-3-qt5-building-issue/400 "2019-03-05T04:07:04Z")

</div>

Good day VTK users, I’m trying to use VTK within a QT application on VS2017. I managed to build VTK6.3 and Qt on VS 64x but when I drag and drop QVTKWidget on my ui and build, I get the following: \_1&gt;MainWindo…

[Previous page](https://discourse.vtk.org/latest.md?page=254)

[Next page](https://discourse.vtk.org/latest.md?page=256)