# Offscreen rendering of MPR window

**URL:** https://discourse.vtk.org/t/offscreen-rendering-of-mpr-window/15322
**Category:** Development
**Created:** [February 26, 2025, 3:42pm UTC](https://discourse.vtk.org/t/offscreen-rendering-of-mpr-window/15322 "2025-02-26T15:42:33Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![mcaa](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/m/bbe5ce/32.png) [@mcaa](https://discourse.vtk.org/u/mcaa)
#### Post date: [February 26, 2025, 3:42pm UTC](https://discourse.vtk.org/t/offscreen-rendering-of-mpr-window/15322/1 "2025-02-26T15:42:33Z")

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Hello dear vtk community,

I’m contributing to an application that uses vtk 9.1 to visualize volumes and MPR slices. The UI has 4 render windows (vtkRenderWindow) - one for the 3D volume and one window for each axial, coronal and sagittal slice. My task is to create a print document with the content of the render windows. Therefore I create a offscreen window and apply the process described here ([https://examples.vtk.org/site/Cxx/Utilities/OffScreenRendering/](https://examples.vtk.org/site/Cxx/Utilities/OffScreenRendering/)) to each of the four render windows.

The offscreen rendering works well for the 3D volume - here a bitmap with the 3D view is created. But the three MPR windows are not rendered. The resulting bitmaps are black.

Please advise me on how to offscreen-render the windows with MPR projections or how to debug the problem.