When emitting points in a Lagoa simulation, there are different options that you can choose that have a big impact on the resulting simulation. This includes the type of Emit node, the number of emitter objects, the size and shape of the emitter objects, and the Resolution Per Unit value you set for the emission.
You can use multiple emitter objects to have create several particle emissions in one ICE tree using one point cloud. The emitter objects must be in a group. Groups allow you to easily add objects to, or delete objects from, the group while keeping the same Get Data node plugged into the ICE tree.
Because the group is plugged into the same Lagoa Emit node, all the settings there apply to both emitter objects. For example, if their sizes are different, the same Resolution Per Unit is still used, so you will get fewer particles emitted from a smaller object.
When you are using multiple volume emitter objects, you need to plug the compound into an ICETree node for each of the volume emitter objects. This compound allows the Lagoa Emit Volume compound to properly compute the proper transform and bounding box limits of each emitter so that it can create particles.
When you emit Lagoa particles, the emitter object is the region in which the particle volume is initially contained and calculated. This region is divided up into Softimage units, and each unit is subdivided into cells. Each unit represents a fixed space of 10 cm and cannot be changed.
The Resolution Per Unit parameter in the Lagoa Emit nodes (see for details) sets the density (points per unit ratio) of the particles based on the number of units into which the emitter object can be divided, and then scales the particles appropriately.
A value of 1 means that one point is created per unit inside the volume. A lower value means that the density that is trying to be achieved per unit will require more (and smaller) points to fill the same volume. The point size is updated at emission, and shows you the granularity of the simulation. The smaller the point, the more detail in the simulation.
You can think of the Resolution parameter as your particle "budget": if you have a budget for many, many particles, then use as small a Resolution Per Unit value as you need! If not, then you need to balance the Resolution Per Unit value with the desired effect for your particle simulation.
As you can imagine, the size and shape of the emitter object has a large part to play in the size and number of particles that are created in the volume. This matters whether the emitter is a volume object or a null. For nulls, you can set their shape in their property editor.
The Lagoa Emit node tries to put in as many points of mass as can fit inside the emitter volume's space. The points are arranged into a neat grid (Uniform Placement) within this volume upon creation by default, but you can change the formation using the Generate options in the Lagoa Emit node.
The Tetrahedral option creates four times more points around each cell center. This results in smaller points with little space between them, so you can create highly incompressible matter this way or very high friction materials.
This is useful for creating fluid effects, when you need many particles, but you don't want to lower the Resolution Per Unit value. It's also the best choice if you want to simulate volume-preserving soft bodies.