# How to set GroupIds (c1) in object (.obj) file?
**URL:** https://discourse.paraview.org/t/how-to-set-groupids-c1-in-object-obj-file/1946
**Category:** Web Support
**Created:** [May 28, 2019, 3:42pm UTC](https://discourse.paraview.org/t/how-to-set-groupids-c1-in-object-obj-file/1946 "2019-05-28T15:42:05Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@bamazap](https://discourse.paraview.org/u/bamazap)
#### Post date: [May 28, 2019, 3:42pm UTC](https://discourse.paraview.org/t/how-to-set-groupids-c1-in-object-obj-file/1946/1 "2019-05-28T15:42:05Z")
I have an object file and am trying to use ParaViewWeb Visualizer to visualize it. I would like to use GroupIds to present different sections of the surface in different colors. How can I set these in an object file?
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [June 3, 2019, 12:51pm UTC](https://discourse.paraview.org/t/how-to-set-groupids-c1-in-object-obj-file/1946/2 "2019-06-03T12:51:57Z")
You do not seem to be in the right category, I’ve moved your topic.
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### Author:  [@jourdain](https://discourse.paraview.org/u/jourdain)
#### Post date: [August 5, 2019, 3:49pm UTC](https://discourse.paraview.org/t/how-to-set-groupids-c1-in-object-obj-file/1946/3 "2019-08-05T15:49:01Z")
The VTK reader of OBJ does not actually split the geometry in group such as a multi-block. But in vtk.js we do have that freedom. Taking the vtk.js implementation of the OBJ reader and converting it in Python as a Python Plugin Source would allow you to produce a multiblock and start leveraging coloring and visibility control within ParaView and therefore in Visualizer.