Pyvista mesh generator

[Josh Rackham (jrackham-mo)]

Closes #92 . Closes #59

To be completed prior to review request and updated as required during the review process.

If the answer to an item on the list is not applicable, feel free to replace the checkbox with 'N/A' to give extra clarity.

All developers are reminded to follow the ancil working practices

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Branch

Related branches (e.g. ug-ancillary-file-science):
N/A

UG-ANTS rose stem logs
UG-ANTS/run2

ug-ancillary-file-science rose stem logs
ug-ancillary-file-science/run4

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Testing

For core UG-ANTS only tests, the bare minimum that will be accepted is the group=unittests but many, if not most, changes will need to test other groups to ensure they meet reviewer expectations. In general, it should be possible and is advised to run the group=all group prior to review submission as this will catch any consequential issues. Additionally you must run the ug-ancillary-file-science tests, pointing at your branch, with group=all to capture any behaviour changes affecting Science codes.

If your change will alter existing science results, you will need to seek appropriate Scientific validation and confirm that the model has been initialised with your new development. Inspecting a change in xconv/pyplot/visualiser of choice is not sufficient to demonstrate the model can be initialised from your file.

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Impact of change

• This will maintain results for UG-ANTS cylc vip ./rose-stem -z group=all tests
• This will this maintain results for ug-ancillary-file-science cylc vip ./rose-stem -z group=all tests
• If this change adds a new capability, evidence has been supplied to show testing of ancillary generation across different resolutions e.g. For global ancillary generation capabilities for use in NWP C896 is expected to have been tested
• This change has significantly impacted required resources (runtime and memory) in existing ancillary generation (if yes, give details)
• This change alters existing ancils

Add further comments/details for your reviewers here on the impacts of the change......

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Approvals for this change

• I have approval from the UG-ANTS core development team for these changes

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New functionality further testing

• If adding new functionality to existing codes, I confirm that the new code doesn't change results when it is switched off and ''works'' when switched on
• Unittests have been added
• Rose stem tests have been added for any new functionality
• I have not encountered any failures in my rose-stem output(s)
  These tasks must succeed for your ticket to pass review.
• I have remembered to run the code style check tasks/tools

Add details of any further testing here.

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Other

• I have read the Contributor Licence Agreement
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• The ticket labels, milestones, etc. are correct
• Links to all related tickets have been provided in the ticket description
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• Source data has been added or changed - please include a link to the license

I confirm that all code is my own and that my contributions are not subject to copyright or license restrictions (see Contributor Licence Agreement).	Josh Rackham
I confirm I have not knowingly violated intellectual property rights (IPR) and have taken sensible measures to prevent doing so, including appropriate attribution for usage of Generative AI. I confirm that this work is my own, and I understand that it is my responsibility to ensure I am not violating others’ IPR. This includes taking reasonable steps to ensure that all tools used while creating this contribution did not infringe IPR.	Josh Rackham

Please add any further notes here. If Generative AI tools have been used, a brief summary should be provided.
GitHub copilot used to add unit tests for the new stock mesh/cube generators

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Rose stem logs

Please copy in the contents of your trac_status.log file(s) below (found in the cylc-run directory for your rose stem run) to your rose-stem testing here. Note: if your changes lead to a change in answers, you must run cylc vip ./rose-stem -z group=all to help ensure all affected configurations has been flagged up.

Add workflow_status.log contents for UG-ANTS rose-stem here. Mon 17 Aug 13:38:20 BST 2026 Git status: [ "" ] Commit: 302a055

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Test Results - Summary

tasks	total
succeeded	65

Test Results - Detail

task	status
install_cold	succeeded
ruff	succeeded
ancil_regrid_mesh_to_mesh_bilinear	succeeded
ancil_regrid_grid_to_mesh_use_input_weights_nearest	succeeded
ancil_regrid_mesh_to_mesh_conservative	succeeded
ancil_regrid_mesh_to_mesh_nearest	succeeded
ancil_regrid_grid_to_mesh_output_weights_nearest	succeeded
ancil_regrid_grid_to_mesh_output_weights_conservative	succeeded
ancil_regrid_mesh_to_grid_nearest	succeeded
ancil_regrid_mesh_to_mesh_conservative_tolerance	succeeded
ancil_split_by_latitude_grid_to_mesh	succeeded
ancil_fill_missing_points_with_target_mask	succeeded
ancil_regrid_mesh_to_grid_output_weights_conservative	succeeded
ancil_regrid_grid_to_mesh_conservative	succeeded
build_docs	succeeded
black	succeeded
ancil_generate_mask_sea	succeeded
ancil_regrid_mesh_to_grid_use_input_weights_conservative	succeeded
ancil_regrid_mesh_to_grid_bilinear	succeeded
ancil_ugrid_to_XIOS	succeeded
ancil_fill_missing_points_no_target_mask	succeeded
ancil_regrid_grid_to_mesh_conservative_tolerance	succeeded
ancil_regrid_mesh_to_grid_conservative	succeeded
ancil_regrid_mesh_to_grid_output_weights_bilinear	succeeded
ancil_generate_mask_land	succeeded
ancil_regrid_grid_to_mesh_bilinear_tolerance	succeeded
ancil_ugrid_to_XIOS_single	succeeded
ancil_regrid_grid_to_mesh_use_input_weights_conservative	succeeded
ancil_regrid_grid_to_mesh_output_weights_bilinear	succeeded
ancil_split_by_latitude_mesh_to_grid	succeeded
unittests	succeeded
ancil_regrid_mesh_to_grid_output_weights_nearest	succeeded
ancil_regrid_mesh_to_grid_use_input_weights_bilinear	succeeded
ancil_regrid_mesh_to_mesh_bilinear_tolerance	succeeded
ancil_regrid_grid_to_mesh_use_input_weights_bilinear	succeeded
ancil_regrid_mesh_to_grid_use_input_weights_nearest	succeeded
ancil_regrid_grid_to_mesh_nearest	succeeded
ancil_extract_mesh	succeeded
ancil_regrid_grid_to_mesh_bilinear	succeeded
rose_ana_extract_mesh	succeeded
rose_ana_generate_mask	succeeded
rose_ana_fill_missing_points	succeeded
rose_ana_regrid_grid_to_mesh	succeeded
rose_ana_regrid_mesh_to_grid	succeeded
rose_ana_ugrid_to_XIOS	succeeded
rose_ana_regrid_mesh_to_mesh	succeeded
ancil_band_regrid_grid_to_mesh_conservative_tolerance	succeeded
ancil_band_regrid_grid_to_mesh_nearest	succeeded
ancil_band_regrid_grid_to_mesh_bilinear_tolerance	succeeded
ancil_band_regrid_grid_to_mesh_bilinear	succeeded
ancil_band_regrid_grid_to_mesh_conservative	succeeded
ancil_band_regrid_mesh_to_grid_conservative	succeeded
ancil_band_regrid_mesh_to_grid_nearest	succeeded
ancil_band_regrid_mesh_to_grid_bilinear	succeeded
linkcheck	succeeded
ancil_recombine_mesh_bands_bilinear_tolerance	succeeded
ancil_recombine_mesh_bands_nearest	succeeded
ancil_recombine_grid_bands_bilinear	succeeded
ancil_recombine_mesh_bands_bilinear	succeeded
ancil_recombine_mesh_bands_conservative	succeeded
ancil_recombine_grid_bands_nearest	succeeded
ancil_recombine_mesh_bands_conservative_tolerance	succeeded
ancil_recombine_grid_bands_conservative	succeeded
rose_ana_band_regrid_grid_to_mesh	succeeded
rose_ana_band_regrid_mesh_to_grid	succeeded

Mon 17 Aug 11:45:43 BST 2026 Git status: [ " M app/install_cold/rose-app.conf" ] Commit: f59312e886fb320c5dfb12228a1438e2e5627777

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Test Results - Summary

tasks	total
succeeded	46

Test Results - Detail

task	status
install_cold	succeeded
subgrid_orography_unittests	succeeded
ancil_apply_mask_invert	succeeded
apply_mask_unittests	succeeded
ancil_regrid_zonal_mean	succeeded
ancil_apply_mask_replacezero	succeeded
ancil_soils_hydrology_dominant_parameters	succeeded
regrid_zonal_mean_unittests	succeeded
add_zeroth_level_unittests	succeeded
ancil_soil_dust	succeeded
soil_params_unittests	succeeded
ancil_lai	succeeded
add_lakes_unittests	succeeded
canopy_heights_unittests	succeeded
soil_roughness_unittests	succeeded
black	succeeded
ostia2nwp_unittests	succeeded
ancil_apply_mask_default	succeeded
ruff	succeeded
ancil_soil_roughness_postproc	succeeded
ancil_lct	succeeded
example_unittests	succeeded
ancil_example	succeeded
ancil_lct_unittests	succeeded
ancil_soil_roughness_postproc_land	succeeded
ancil_subgrid_orography	succeeded
ancil_canopy_heights	succeeded
ancil_add_zeroth_level	succeeded
soil_dust_unittests	succeeded
build_docs	succeeded
lai_unittests	succeeded
rose_ana_apply_mask	succeeded
rose_ana_add_zeroth_level	succeeded
rose_ana_example	succeeded
rose_ana_canopy_heights	succeeded
rose_ana_subgrid_orography	succeeded
rose_ana_soil_roughness_postproc_land	succeeded
rose_ana_soil_roughness_postproc	succeeded
rose_ana_regrid_zonal_mean	succeeded
rose_ana_ancil_lct	succeeded
rose_ana_lai	succeeded
rose_ana_soil_dust	succeeded
ancil_soils_hydrology_average_parameters	succeeded
linkcheck	succeeded
ancil_soils_hydrology_make_consistent	succeeded
rose_ana_soil_params	succeeded

[Josh Rackham (jrackham-mo)]

Noting that there was a failing unit test in the split mesh-to-grid regrid (lib/ugants/tests/regrid/applications/test_integration.py::TestConsistentResults::test_no_tolerance[bilinear-4]). Difference plot attached (expected - actual):

Expected: global-to-global mesh-to-grid regrid.
Actual: split-regrid-recombine mesh-to-grid regrid, with 4 bands.
Both using bilinear method.

There are a bunch of masked points (the white points in the plot), which appear masked in both the expected and actual (due to SciTools/iris-esmf-regrid#391, now fixed in later versions of iris-esmf-regrid). There are also a few points where there are actual differences.

As a result I have decided to increase the source data resolution for this test from C4 to C12 (splitting a C4 into 4 bands is a fairly unrealistic test of our banded regrid): 302a055