# How to render multiBlock Image data by Volume representation

**URL:** https://discourse.paraview.org/t/how-to-render-multiblock-image-data-by-volume-representation/3238
**Category:** Development
**Created:** [December 28, 2019, 6:22am UTC](https://discourse.paraview.org/t/how-to-render-multiblock-image-data-by-volume-representation/3238 "2019-12-28T06:22:48Z")
**Posts on this page:** 6
**Page:** 1

<div class="post-metadata">

### Author: ![sharon](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/s/67e7ee/32.png) [@sharon](https://discourse.paraview.org/u/sharon)
#### Post date: [December 28, 2019, 6:22am UTC](https://discourse.paraview.org/t/how-to-render-multiblock-image-data-by-volume-representation/3238/1 "2019-12-28T06:22:48Z")

</div>

Dear Experts,

i found when i put several vtkImageData into vtkMultiBlockDataSet, i cannot select “Volume” representation.

It seems the output data type is “vtkMultiBlockDataSet” not “vtkImageData”, so in the paraview representation GUI, there is no “Volume” option to choose…?

How can i make such multi block image data to be rendered by volume representation?

Thanks and Best Regards,  
Sharon

---

<div class="post-metadata">

### Author: ![cory.quammen](https://discourse.paraview.org/user_avatar/discourse.paraview.org/cory.quammen/32/11193_2.png) [@cory.quammen](https://discourse.paraview.org/u/cory.quammen)
#### Post date: [January 2, 2020, 10:53pm UTC](https://discourse.paraview.org/t/how-to-render-multiblock-image-data-by-volume-representation/3238/2 "2020-01-02T22:53:03Z")

</div>

Alas, volume rendering of any multiblock data is not [well supported](https://gitlab.kitware.com/paraview/paraview/issues/15443). As a not terribly efficient workaround, you can use a **Resample to Image** filter to enable volume rendering. It is definitely not ideal, but works in a pinch.

---

<div class="post-metadata">

### Author: ![wascott](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/w/8e8cbc/32.png) [@wascott](https://discourse.paraview.org/u/wascott)
#### Post date: [January 2, 2020, 11:35pm UTC](https://discourse.paraview.org/t/how-to-render-multiblock-image-data-by-volume-representation/3238/3 "2020-01-02T23:35:13Z")

</div>

Cory, would another option be the Merge Blocks filter?

---

<div class="post-metadata">

### Author: ![cory.quammen](https://discourse.paraview.org/user_avatar/discourse.paraview.org/cory.quammen/32/11193_2.png) [@cory.quammen](https://discourse.paraview.org/u/cory.quammen)
#### Post date: [January 3, 2020, 4:23am UTC](https://discourse.paraview.org/t/how-to-render-multiblock-image-data-by-volume-representation/3238/4 "2020-01-03T04:23:09Z")

</div>

**Merge Blocks** would enable volume rendering, but it would greatly expand the memory footprint because all grids would be converted to unstructured grids. If you start with a multiblock of unstructured grids, then that’s not a big deal, but coming from image data it is a bigger deal.

---

<div class="post-metadata">

### Author: ![wascott](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/w/8e8cbc/32.png) [@wascott](https://discourse.paraview.org/u/wascott)
#### Post date: [January 4, 2020, 7:23pm UTC](https://discourse.paraview.org/t/how-to-render-multiblock-image-data-by-volume-representation/3238/5 "2020-01-04T19:23:33Z")

</div>

You are correct, of course. I keep forgetting that multiblock data can be non unstructured grid.

---

<div class="post-metadata">

### Author: ![sharon](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/s/67e7ee/32.png) [@sharon](https://discourse.paraview.org/u/sharon)
#### Post date: [January 7, 2020, 4:07am UTC](https://discourse.paraview.org/t/how-to-render-multiblock-image-data-by-volume-representation/3238/6 "2020-01-07T04:07:48Z")

</div>

@cory.quammen @wascott

Thank you Cory and Waltter very much!!  
Your information is very helpful for me!

Best Regards