We are trying to figure out a workflow for importing the results of a pedestrian simulation into Blender for visualization. During the simulation, pedestrians enter into the simulation at various times, walk around for a while, then disappear as they exit the simulation.

Simulation results are currently exported as an Alembic file. When we try to import that file into Blender, what we end up with is all pedestrians being visible at all times, even before they enter the simulation and after they exit.

The alembic objects have a visibility property, but even if I set that to false for all samples of all objects, they still show up in Blender.

Is there a way to either make Blender respect the visibility in the Alembic file, or else quickly keyframe the visibility after import (keeping in mind that a typical simulation will have thousands of pedestrians all entering at different times, making individual keyframing for each agent impractical)?

  • $\begingroup$ from my quick test of a round trip (export, then import), blender does not respect visibility animation in abc files, and also doesn't properly import a hidden mesh. This is a bug you should report. Unfortunately for your project, bugs take time to fix. $\endgroup$
    – james_t
    Jul 20 at 15:24
  • 1
    $\begingroup$ Thanks @james_t. There is an existing bug report about this issue: projects.blender.org/blender/blender/issues/69191. It would still be nice to have some workaround, but it looks like using Alembic just isn't going to work for this project. $\endgroup$
    – jsarup
    Jul 20 at 15:40
  • $\begingroup$ as an ex-software PM, i empathize with expensive planning that must be scrapped. $\endgroup$
    – james_t
    Jul 21 at 18:21


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