# \[Volume Rendering\] Works via python console but not via extension code
**URL:** https://discourse.slicer.org/t/volume-rendering-works-via-python-console-but-not-via-extension-code/23248
**Category:** Development
**Tags:** python
**Created:** [May 2, 2022, 9:05pm UTC](https://discourse.slicer.org/t/volume-rendering-works-via-python-console-but-not-via-extension-code/23248 "2022-05-02T21:05:11Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@strider\_hunter](https://discourse.slicer.org/u/strider_hunter)
#### Post date: [May 2, 2022, 9:05pm UTC](https://discourse.slicer.org/t/volume-rendering-works-via-python-console-but-not-via-extension-code/23248/1 "2022-05-02T21:05:11Z")
Hi,
When I use the following code in my Slicer Extension (Slicer 4.11.20210226), I am unable to get a volume render in the 3D view (a custom vtkMRMLViewNode).
```auto
node = slicer.util.getNode('') # a vtkMRMLScalarVolumeNode
volRenLogic = slicer.modules.volumerendering.logic()
displayNode = volRenLogic.CreateDefaultVolumeRenderingNodes(node)
displayNode.SetVisibility(True)
```
But when I copy paste the same to the python console, it works! Upon checking the volume rendering module, I noticed that my extension code does not set the eye icon to visible, but copy-pasting the code in the python console does that. In my extension, I also use the following displayNode functions to verify if the visibility was set properly and their output is all 1.
`print (' ------ [myUtil.set3DBackground()]: ', displayNode.GetVisibility(), displayNode.GetVisibility2D(), displayNode.GetVisibility3D())`
What may I be missing here?
* * *
Note: Prior to the volume rendering, my extension updates the 3D array that makes up the `vtkMRMLScalarVolumeNode` being rendered.
---
### Author:  [@mau\_igna\_06](https://discourse.slicer.org/u/mau_igna_06)
#### Post date: [May 2, 2022, 11:58pm UTC](https://discourse.slicer.org/t/volume-rendering-works-via-python-console-but-not-via-extension-code/23248/2 "2022-05-02T23:58:51Z")
May be use a timer callback to set up the volume rendering because you need to give some time to the scalar volume to update I think
---
### Author:  [@strider\_hunter](https://discourse.slicer.org/u/strider_hunter)
#### Post date: [May 4, 2022, 7:58am UTC](https://discourse.slicer.org/t/volume-rendering-works-via-python-console-but-not-via-extension-code/23248/3 "2022-05-04T07:58:42Z")
Thanks! It worked with the timer!
```auto
def set3DBackgroundTimed(node):
displayNode = volRenLogic.CreateDefaultVolumeRenderingNodes(node)
displayNode.SetVisibility(True)
qt.QTimer.singleShot(1000, lambda: set3DBackgroundTimed(node))
```