Nastasha Wijers

The 3D version of this grid deposition [pixelization_routines.pyx, line 1607 onwards](https://github.com/yt-project/yt/blob/8ef156989728d1b6af6c24c342974e3d352cdf9f/yt/utilities/lib/pixelization_routines.pyx#L1607): `pixelize_sph_kernel_arbitrary_grid` seems to handle the 3D part just find, but again sets minimum smoothing lengths (for the kernel evaluation,...

I think I have the `ProjectionPlot` issues fixed on this branch: [https://github.com/nastasha-w/yt/tree/sph_proj_backend](https://github.com/nastasha-w/yt/tree/sph_proj_backend). This means both the fixes to the on-axis projection plots for SPH datasets, and the addition of an...

I did put the tests I used in a script (attached): [sph_pixelization_tests_2024-07-03.py.zip](https://github.com/user-attachments/files/16090389/sph_pixelization_tests_2024-07-03.py.zip) I haven't put those into the main test suite yet, but that should hopefully not be too difficult....

Thanks! Here's the PR: #4939

Based on some tests with PR #4939 ([this comment](https://github.com/yt-project/yt/pull/4939#issuecomment-2243898838)), I can now confirm that on test datasets from OWLS and Arepo, the resolution effects I showed in a test case...

Thanks @JBorrow! I had seen that paper a while ago. The backend here uses a bit of a different approach from that paper: instead of dividing the mass/number of ions/other...

Honestly, a bigger worry for me is currently the periodic edge handling. The way this currently works is that, if a simulation is periodic in a particular coordinate direction, particles...

I've addressed the periodicity concern above in PR #4939 now ([comment describing the effect](https://github.com/yt-project/yt/pull/4939#issuecomment-2248468277)).

I've brought up a possible issue with the `ProjectionPlot` pixelization routine on the development slack channel, but that's to do with the handling of small SPH particles (smoothing length <...

The small-particle issue for the SPH `ProjectionPlot`s is a separate one, but I can open a different pull request for it. I feel like I might need to think that...