# Forcing rendering

**URL:** https://discourse.vtk.org/t/forcing-rendering/5692
**Category:** Support
**Created:** [May 3, 2021, 5:20pm UTC](https://discourse.vtk.org/t/forcing-rendering/5692 "2021-05-03T17:20:23Z")
**Posts on this page:** 2
**Page:** 1

<div class="post-metadata">

### Author: ![Luis\_Carlos\_Carneiro](https://discourse.vtk.org/user_avatar/discourse.vtk.org/luis_carlos_carneiro/32/1360_2.png) [@Luis\_Carlos\_Carneiro](https://discourse.vtk.org/u/Luis_Carlos_Carneiro)
#### Post date: [May 3, 2021, 5:20pm UTC](https://discourse.vtk.org/t/forcing-rendering/5692/1 "2021-05-03T17:20:23Z")

</div>

Dear All,

I do the rendering of several volumes in same 3D image.  
Some of them are over the others and shadow the previous rendered ones.  
How I force re-render the previous ones (volumes) to appear the shadowed areas? (and to shadow the new ones areas instead)  
I tried to do the following (to the previous ones). I added again the volume (the volumeMapper and volume was not reallocated but used the previous allocation)

```
    volumeMapper.SetInputConnection(reader.GetOutputPort())
    renderer.AddVolume(volume)
    renderWindow.Render()

```

But the new volumes remains over the old ones (previous ones) contrary to what I want.

Thanks,

Luís Gonçalves

---

<div class="post-metadata">

### Author: ![Luis\_Carlos\_Carneiro](https://discourse.vtk.org/user_avatar/discourse.vtk.org/luis_carlos_carneiro/32/1360_2.png) [@Luis\_Carlos\_Carneiro](https://discourse.vtk.org/u/Luis_Carlos_Carneiro)
#### Post date: [May 4, 2021, 4:04pm UTC](https://discourse.vtk.org/t/forcing-rendering/5692/2 "2021-05-04T16:04:56Z")

</div>

renderer.RemoveVolume(volume)

And re-render the previous volume again.