I have a problem visualising a large system of 188M atoms. Up to 134M atoms, everything works fine. But when the system is 135M atoms or more, Ovito (v3.14, free) opens the file, sees there are 188M in it, but doesn’t show any of the atoms. When I reduce the system to the first or last 100M atoms, both show fine, so it doesn’t appear that the issue is in the lines with atom data. I also tried opening the files as both lammps datafiles and dump files, but I get then same problem with both formats.
I’m running Ovito on an Apple Silicon Macbook Pro running macOS Sequoia 15.6.1, 32GB or RAMM.
Are there any Ovito users on Apple Silicon who can open 135M+ atom lammps files? Would anyone be willing to try opening my large file?
As of OVITO 3.14, The software can render a maximum of 134,217,727 spherical particles with the OpenGL renderer. This is a limitation imposed by the OpenGL rendering interface, which can process data buffers with a maximum size of 2^31 bytes (~2 GB). Since each sphere requires 12 bytes (x, y, z, radius), only 134M fit into an OpenGL memory buffer.
To overcome this limit, we would have to implement a more complex rendering system that sends the particle data to the GPU in chunks. If there is a need for this, we would be happy to check how much development work such an extension would require.
Thanks for letting me know about the maximum atom limit.
You mentioned ‘As of version 3.14’. Am I correct in thinking that olders versions do not have this limit? That would be a very good workaround for me, as I don’t use any of the latest features. I could very well use an older version if that lets me go up to half half a billion atoms.
Can older versions go to higher numbers of atoms, and iif so, what is the latest version for Apple Silicon Macs that does not have the 134M atom limit?
No, sorry, all previous versions of OVITO are subject to the same limitation. I just wanted to mention which version is the current one - in case anyone reads this in the future when things may have changed.
Ok. In that case, let me add one vote to the tally of those who would like to see the GPU rendering done in multiple 2GB chunks, to remove the atom number limit. At 134M atoms, Ovito still handles systems pretty smoothly, so hardware capability is not a narrow bottleneck. It would be nice if the software could push the hardware to its limits.
I have now found time to improve the OpenGL code for the rendering of particles and overcome the limit of 134M spheres. The new hard limit for the OpenGL renderer is now ~2.1 billion particles (on the software side). Feel free to give it a try. Here you can find a new dev build:
Oh excellent! The developer version 3.14.1 works like a charm for me. I can visualise a 206.5M atom system fine and there is only a modest time lag when rotating, zooming, etc. Hardware used for that is an early 2023 Macbook Pro with M2 Pro cpu, 32 GB of memory. So it doesn’t even require the latest top model to smoothly handle hundreds of millions of atoms.
Many thanks for the quick action to my post only a few days ago. 
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