# Crash when the render window is called

**URL:** https://discourse.vtk.org/t/crash-when-the-render-window-is-called/13709
**Category:** Support
**Created:** [April 14, 2024, 1:59am UTC](https://discourse.vtk.org/t/crash-when-the-render-window-is-called/13709 "2024-04-14T01:59:02Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![Xiao\_Xu](https://discourse.vtk.org/user_avatar/discourse.vtk.org/xiao_xu/32/8726_2.png) [@Xiao\_Xu](https://discourse.vtk.org/u/Xiao_Xu)
#### Post date: [April 14, 2024, 1:59am UTC](https://discourse.vtk.org/t/crash-when-the-render-window-is-called/13709/1 "2024-04-14T01:59:03Z")

</div>

Hi, I am writing a python program to calculate the curvature of a 3D vtk model and show the result with a colormap. However, every time when I start the render window and the render window interactor, a crash happens. I am wondering how I can solve this problem. Thanks!

More details which might help:

1. The vtk version I pip installed is 9.2.4, python version is 3.11.5 on Linux.

2. The code causes crashing:  
iren.Initialize()  
renWin.Render()

3. The whole code:  
from vtkmodules.vtkCommonCore import vtkLookupTable  
from vtkmodules.vtkFiltersCore import vtkCleanPolyData  
from vtkmodules.vtkFiltersGeneral import vtkCurvatures  
from vtkmodules.vtkFiltersSources import vtkSuperquadricSource  
from vtkmodules.vtkRenderingCore import (  
vtkActor,  
vtkCamera,  
vtkPolyDataMapper,  
vtkRenderWindow,  
vtkRenderWindowInteractor,  
vtkRenderer,  
vtkDataSetMapper,  
)  
import vtkmodules.vtkInteractionStyle  
import vtkmodules.vtkRenderingFreeType  
import vtkmodules.vtkRenderingOpenGL2  
from vtkmodules.vtkIOLegacy import vtkPolyDataReader

# Read vtk file

reader = vtkPolyDataReader()  
reader.SetFileName(“/mnt/md0/tempFolder/xiao/ICAC/curv/780/780\_cal\_left\_model.vtk”)  
reader.Update()

# calculate curvature

curve1 = vtkCurvatures()  
curve1.SetInputConnection(reader.GetOutputPort())  
curve1.SetCurvatureTypeToGaussian()  
curve1.Update()

# create colormap

lut1 = vtkLookupTable()  
lut1.SetNumberOfColors(256)  
lut1.SetHueRange(0.15,1.0)  
lut1.SetSaturationRange(1.0,1.0)  
lut1.SetValueRange(1.0,1.0)  
lut1.SetAlphaRange(1.0,1.0)  
lut1.SetRange(-20,20)

# map the curvature data with colormap

cmapper1 = vtkPolyDataMapper()  
cmapper1.SetInputConnection(curve1.GetOutputPort())  
cmapper1.SetLookupTable(lut1)  
cmapper1.SetUseLookupTableScalarRange(1)

# actor

cActor1 = vtkActor()  
cActor1.SetMapper(cmapper1)  
cActor1.SetPosition(-0.5,0.0,0.0)

# Create renderer stuff

ren1 = vtkRenderer()  
renWin = vtkRenderWindow()  
renWin.AddRenderer(ren1)  
iren = vtkRenderWindowInteractor()  
iren.SetRenderWindow(renWin)

# Add the actors to the renderer

ren1.AddActor(cActor1)  
ren1.SetBackground(0.5,0.5,0.5)  
ren1.ResetCamera()  
renWin.SetSize(300,200)

# camera

camera = vtkCamera()  
ren1.SetActiveCamera(camera)  
camera.SetPosition(0.0,2.0,2.1)  
camera.SetFocalPoint(0.0,0.0,0.0)  
camera.SetViewAngle(30)  
ren1.ResetCameraClippingRange()  
iren.Initialize()

# render the image

# prevent the tk window from showing up then start the event loop

renWin.Render()

# # — end of script –