# what are the minimum requirements for ghosting (halo cells)?

**URL:** https://discourse.paraview.org/t/what-are-the-minimum-requirements-for-ghosting-halo-cells/1138
**Category:** ParaView Support
**Created:** [January 14, 2019, 5:47pm UTC](https://discourse.paraview.org/t/what-are-the-minimum-requirements-for-ghosting-halo-cells/1138 "2019-01-14T17:47:07Z")
**Posts on this page:** 1
**Showing post:** 2

<div class="post-metadata">

### Author: ![Andy\_Bauer](https://discourse.paraview.org/user_avatar/discourse.paraview.org/andy_bauer/32/5442_2.png) [@Andy\_Bauer](https://discourse.paraview.org/u/Andy_Bauer)
#### Post date: [January 14, 2019, 6:00pm UTC](https://discourse.paraview.org/t/what-are-the-minimum-requirements-for-ghosting-halo-cells/1138/2 "2019-01-14T18:00:47Z")

</div>

Before starting a long discussion, VTK made a change a while back to be consistent with VisIt’s way of marking ghost entities – [https://blog.kitware.com/ghost-and-blanking-visibility-changes/](https://blog.kitware.com/ghost-and-blanking-visibility-changes/).

This can get complex quite fast, especially when considering trying to handle multiple levels of ghost cells. Also, many filters use ghost information quite differently so a simplification for one filter wouldn’t work for another and this information would have to be passe through the pipeline (e.g. ghost level one requires simplification A while ghost level two requires simplification B, which probably just means that you could only do simplification B on the second ghost level).

I thought about going down the route of just saying what types of ghost adjancies would be requested at a level (e.g. face ghosts which are only needed for determining the exterior surface vs. edge ghosts which I can’t think of a good example off the top of my head vs. point ghosts which are needed for the point data to cell data filter) but even that’s quite a bit of work.

I’d be happy to give feedback but I fear that the conclusion will be that this is going to be too much of a change and will also break compatibility with VisIt.

Best,  
Andy

---

_[View the full topic](https://discourse.paraview.org/t/what-are-the-minimum-requirements-for-ghosting-halo-cells/1138)._