# Volume representation as categories
**URL:** https://discourse.paraview.org/t/volume-representation-as-categories/7262
**Category:** ParaView Support
**Created:** [May 20, 2021, 1:52pm UTC](https://discourse.paraview.org/t/volume-representation-as-categories/7262 "2021-05-20T13:52:14Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@schupin](https://discourse.paraview.org/u/schupin)
#### Post date: [May 20, 2021, 1:52pm UTC](https://discourse.paraview.org/t/volume-representation-as-categories/7262/1 "2021-05-20T13:52:14Z")
Hi,
I’m trying to view an image file (.vti) in wich each areas are identified by a unsigned int value (between 1 and 500 for instance). Unidentified areas have 0 as value.
When I use a volume representation of the data, i can’t clearly see areas identified by number 1 or 2 since I put opacity of 0 to 0.
At the contrary, if I put opacities of areas from 1 to 500 at 1, and interpolation is done between void area (0) and others → almost everything look the same :
I tried to use the “interpert values as categories” button but it seems to do nothing while using a volume representation.
Anyone knows how to get rid of the interpolation of how to look at these kind of data ?
Thanks by advance,
PS: a sample data can be downloaded here ftp://ftp.cea.fr/incoming/y2k01/chupin-sylvain-1621518551/32bits\_labels\_0.vti
---
### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [May 20, 2021, 3:27pm UTC](https://discourse.paraview.org/t/volume-representation-as-categories/7262/2 "2021-05-20T15:27:02Z")
I’m afraid this is a limitation of the Volume rendering representation.
Your dataset is perfectly adapted to the DigitalRocksPhysics plugin tools though. Using ExplodeMaterialCluster filter with a factor of 0 you can get this rendering:
---
### Author:  [@schupin](https://discourse.paraview.org/u/schupin)
#### Post date: [May 20, 2021, 7:24pm UTC](https://discourse.paraview.org/t/volume-representation-as-categories/7262/3 "2021-05-20T19:24:26Z")
Thanks a lot for your quick answer.
I didn’t know this plugin and it work very well for this kind of vizualisation.
Playing with ambient occlusion and tone mapping gave me something great !
---
### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [May 21, 2021, 8:17am UTC](https://discourse.paraview.org/t/volume-representation-as-categories/7262/4 "2021-05-21T08:17:19Z")
@LfxPaul🙂
---
### Author:  [@LfxPaul](https://discourse.paraview.org/u/LfxPaul)
#### Post date: [May 21, 2021, 8:41am UTC](https://discourse.paraview.org/t/volume-representation-as-categories/7262/5 "2021-05-21T08:41:51Z")
Woow nice visualization @schupin ! Love the way occlusion makes the data almost real
---
### Author:  [@steve\_r](https://discourse.paraview.org/u/steve_r)
#### Post date: [May 26, 2021, 1:38pm UTC](https://discourse.paraview.org/t/volume-representation-as-categories/7262/6 "2021-05-26T13:38:17Z")
Looks really cool!
Still, I would love to see “values as categories” being supported for volume data.
---
### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [November 22, 2022, 8:09am UTC](https://discourse.paraview.org/t/volume-representation-as-categories/7262/7 "2022-11-22T08:09:34Z")
A post was split to a new topic: [ExplodeMaterialCluster issue](https://discourse.paraview.org/t/explodematerialcluster-issue/10830)