The Birth Voxels operator allows you to birth particles inside the volume or surface of scene objects, at uniform spatial intervals.
Start/End: controls the time range in which to birth new particles.
Enable every nth: when enabled, particles will be birthed at regular frame intervals, instead of at every frame.
Nth value: the interval value at which to birth particles.
Mode: controls where particles will be birthed, relative to the surface or volume of a particular input object.
Sample type: controls the quality of samples used to determine surface proximity, when birthing particles in “Surface” mode.
Voxel size X/Y/Z: the size of individual voxels, in which particles will be birthed.
Accuracy: controls the accuracy of the raycaster used to compute information about whether a particle is inside or outside of an object’s volume. Increase this value for meshes that are self-intersecting or have holes in them.
If an input object’s surface is not closed, or is self-intersecting, increasing the accuracy value can improve results and reduce artifacts.
Inflate: pushes source mesh vertices along their normals by the specified amount, prior to particle birth. Increasing this value will expand the volume of birthed particles around the source mesh.
Split elements: when enabled, the elements of the source mesh will be split into sub-meshes and processed independently. This can improve results when sub-elements are overlapping, however, if the source mesh is a thin shell (composed of two non-contiguous surfaces representing the inside and outside of the mesh), this should be disabled (otherwise the inside/outside will be processed as two independent meshes, rather than the sides of a single mesh).
Scale type: controls which size value particle will derive their scale from.
Mult: a global scale multiplier applied to all particles.
Grains: choosing this preset will apply a progressive offset to particles, such that their positions in space will form a tightly-knit overlapping grid.
Grid: choosing this preset will remove all offsets from particles, such that their positions in space will form a uniform, aligned grid.