# Discretization **URL:** https://simpeg.discourse.group/c/for-questions-related-to-meshes-and-operators/11.md [Latest](https://simpeg.discourse.group/latest.md) · [Categories](https://simpeg.discourse.group/categories.md) --- ## [About the Discretization category](https://simpeg.discourse.group/t/about-the-discretization-category/71)
**Author:** [@thibaut.astic](https://simpeg.discourse.group/u/thibaut.astic)\ **Replies:** 0
For questions related to Meshes and Operators Use the following paragraphs for a longer description, or to establish category guidelines or rules: Why should people use this category? What is it for? How exactly is th… --- ## [Gridded details](https://simpeg.discourse.group/t/gridded-details/611)
**Author:** [@Alex](https://simpeg.discourse.group/u/Alex)\ **Replies:** 0\ **Last updated:** [September 26, 2024, 2:20pm UTC](https://simpeg.discourse.group/t/gridded-details/611 "2024-09-26T14:20:29Z")
Dear developer, I’m facing challenges in creating a grid for geomagnetic inversion due to the vastness of my data research area, which spans 300,000 meters horizontally and vertically, yet only has a thickness of approxi… --- ## [Exporting models to UBC format](https://simpeg.discourse.group/t/exporting-models-to-ubc-format/502)
**Author:** [@ulrogo](https://simpeg.discourse.group/u/ulrogo)\ **Replies:** 2\ **Last updated:** [September 20, 2023, 4:16pm UTC](https://simpeg.discourse.group/t/exporting-models-to-ubc-format/502 "2023-09-20T16:16:34Z")
I know there are functions (like write\_model\_UBC) to save 2D and 3D models in UBC format. Can you share with me an example of how the function arguments should be defined, as well as the input and output files, please. T… --- ## [Remove some cells from a mesh](https://simpeg.discourse.group/t/remove-some-cells-from-a-mesh/495)
**Author:** [@amin](https://simpeg.discourse.group/u/amin)\ **Replies:** 3\ **Last updated:** [August 25, 2023, 3:07pm UTC](https://simpeg.discourse.group/t/remove-some-cells-from-a-mesh/495 "2023-08-25T15:07:55Z")
Hi everyone! Is there a way to remove arbitrary number of cells from a mesh? To add some context, I need this to “mimic” a domain with some holes. Thanks! --- ## [Using SimplexMesh in SimPEG problems](https://simpeg.discourse.group/t/using-simplexmesh-in-simpeg-problems/478)
**Author:** [@Hello](https://simpeg.discourse.group/u/Hello)\ **Replies:** 0\ **Last updated:** [July 9, 2023, 6:26pm UTC](https://simpeg.discourse.group/t/using-simplexmesh-in-simpeg-problems/478 "2023-07-09T18:26:36Z")
Tell me, please, is it possible to use unstructured (tetrahedral) meshes in any problems in SimPEG? I can read a SimplexMesh from a VTK file, but how can I use it to solve inversion problems? For example, in problems of … --- ## [How to divide octree levels](https://simpeg.discourse.group/t/how-to-divide-octree-levels/275)
**Author:** [@peterfen-eng](https://simpeg.discourse.group/u/peterfen-eng)\ **Replies:** 1\ **Last updated:** [June 6, 2022, 7:06pm UTC](https://simpeg.discourse.group/t/how-to-divide-octree-levels/275 "2022-06-06T19:06:12Z")
When I use Octree in SimPEG, I find that I do not know much about the mesh refinement. In the graph I draw with Octree levels in the example, the meshes are too dense in the middle. Can you tell me how to divide this lev… --- ## [Feedback on unstructured grids](https://simpeg.discourse.group/t/feedback-on-unstructured-grids/254)
**Author:** [@peruz](https://simpeg.discourse.group/u/peruz)\ **Replies:** 2\ **Last updated:** [September 13, 2021, 12:05pm UTC](https://simpeg.discourse.group/t/feedback-on-unstructured-grids/254 "2021-09-13T12:05:00Z")
Hello SimPEG community, I’m Luca Peruzzo, postdoc at the Berkeley Lab. First of all, thank you for this project, very educational, and yet powerful and with real-world applicability. I have worked a little bit with the… --- ## [Are there rules of thumb for defining the size of a mesh in magnetic or gravity inversions?](https://simpeg.discourse.group/t/are-there-rules-of-thumb-for-defining-the-size-of-a-mesh-in-magnetic-or-gravity-inversions/178)
**Author:** [@edur](https://simpeg.discourse.group/u/edur)\ **Replies:** 1\ **Last updated:** [January 19, 2021, 11:55pm UTC](https://simpeg.discourse.group/t/are-there-rules-of-thumb-for-defining-the-size-of-a-mesh-in-magnetic-or-gravity-inversions/178 "2021-01-19T23:55:52Z")
Hi All, I guess each problem is unique when it comes to discretizing the subsurface, nevertheless, I was wondering if there is any key literature on that, or, if some of you have a rule of thumb to explore simple models… --- ## [A warning message when plotting 3D cylindrical mesh](https://simpeg.discourse.group/t/a-warning-message-when-plotting-3d-cylindrical-mesh/171)
**Author:** [@jsun29](https://simpeg.discourse.group/u/jsun29)\ **Replies:** 2\ **Last updated:** [January 4, 2021, 5:24pm UTC](https://simpeg.discourse.group/t/a-warning-message-when-plotting-3d-cylindrical-mesh/171 "2021-01-04T17:24:09Z")
Following the code example on http://discretize.simpeg.xyz/en/master/api/generated/discretize.CylindricalMesh.html#discretize.CylindricalMesh, I created a simple 3D cylindrical mesh using the following code: from SimPEG… --- ## [How to define a difference operator mapping from cell center to cell center](https://simpeg.discourse.group/t/how-to-define-a-difference-operator-mapping-from-cell-center-to-cell-center/149)
**Author:** [@Astor](https://simpeg.discourse.group/u/Astor)\ **Replies:** 7\ **Last updated:** [November 17, 2020, 2:29am UTC](https://simpeg.discourse.group/t/how-to-define-a-difference-operator-mapping-from-cell-center-to-cell-center/149 "2020-11-17T02:29:01Z")
Hi, I would like to add a cross-gradient term in the joint inversion and need to calculate the spatial difference of the model, but I am not so familiar with the operators. Specifically, for a 2D model, the tensor mesh … --- ## [Using mesh\_builder\_xyz](https://simpeg.discourse.group/t/using-mesh-builder-xyz/66)
**Author:** [@RadhikaF](https://simpeg.discourse.group/u/RadhikaF)\ **Replies:** 3\ **Last updated:** [February 27, 2020, 11:21pm UTC](https://simpeg.discourse.group/t/using-mesh-builder-xyz/66 "2020-02-27T23:21:25Z")
Hello everyone, I have just started familiarising myself with SimPEG and looking at its FDEM forward modelling capabilities. I have been exploring examples that use a cylindrical mesh for such problems (thank you for th…