Simulation Options - Caronte

Here you can make basic adjustments to the rigid and soft body dynamics solver, called “Caronte”.

Quality

This parameter ranges from 0 to 100 and determines the solver’s accuracy. With higher settings, simulation times increase. The default value is 60.

Jittering

In previous versions of RealFlow, rigid bodies often showed an unwanted jitter at the beginning of, or after, a simulation. With this parameter it is possible to gradually reduce the effect in a range from 0 to 100, where 0 completely removes the tremble.

Characteristic object properties

RealFlow's body dynamics solver is completely scale-independent. This means that you can always choose the desired quality level without considering the scene's current scale. With a “Quality” level of 50, you have a very good balance between accuracy and simulation speed in most cases. The solver analyses the scene objects to find averages of several attributes – the “Characteristic object properties” values. Based on these results, Caronte will finally configure the best settings to guarantee a correct simulation.

When Do I Need “Characteristic Object Properties”?

A change of the “Characteristic object properties” is only needed when you want to simulate a scene in parts. But, what does “in parts” actually mean? In some cases, a simulation is not performed as a whole, but split into several separate parts. A very good example of this is a prefractured rigid body vase (the pieces are connected with MultiJoints) and soft body flowers falling on the floor. The combination of both rigid and soft bodies can be very time-consuming and this is the reason to use a split workflow:

In the first part, only the vase dynamics is simulated, because the soft flowers will hardly contribute to the complete simulation and the behaviour of the fragments. For this part, the flowers' “Simulation” option is simply set to “Inactive”. Now, the rigid body dynamics is simulated very fast and you will be able to perform many tests within a short period of time. Once you are satisfied with the behaviour of the vase's pieces, activate the flower objects and re-simulate.

What you might observe is a completely different behaviour of the fragments and the MultiJoints. Instead of nicely shaped fragments you have only small chunks, for example, and all of the previous work becomes useless. The reason is that Caronte adjusted scale automatically to react on the new situation. In this example, the small pieces of the vase and the flowers have completely different shapes. The fragments are more or less “spherical”, while the flowers are long and thin.

So, the purpose of the “Characteristic object properties” is to maintain the behaviour of a scene's elements when you perform simulations in parts.

How Do I Adjust “Characteristic Object Properties” ?

Fortunately, it is not difficult to find the working values and you do not have to start dozens of tests. Simply follow these few steps:

Start the simulation with all nodes (here: vase, flowers) set to “Active”.
When you see a change in the progress bar (e.g. 5%), you can stop the simulation. Please bear in mind that it can take some time until the simulation starts when the scene is large.
Check “Overwrite” and transfer the “Last used” values to their associated fields.
Reset and simulate the individual parts (here: a) vase only and b) vase + flowers)

With these four steps you fix the solver's scene adjustment and make sure that the individual elements will not lose their behaviour when simulated in parts. Once you have “pinned” the solver, you are free to do almost anything you want, because Caronte will always work with the pre-adjusted values. If you decide to add completely new elements to an existing scene, on the other hand, then it is possible that the values you have fixed in the original scene are not valid any more. In such a case you have to repeat the four steps and readjust the solver.

What Else Do I Have to Know?

As mentioned, the “Characteristic object distances” normally change when you work with very different objects and perform a simulation in parts: with each part or new elements, Caronte reacts on the modified conditions and this could result in a different behaviour. But, of course, you want to maintain the behaviour throughout the entire simulation and this is exactly what can be done with “Characteristic object distances”.

There are also many situations where it is not necessary to make any changes, for example in one-part simulations. There, you do not have to worry about “Characteristic object distances” at all. Another is, when you simulate in parts, but the objects have very similar sizes and shapes: a typical scene is a fragmented glass with candies.

It is also not mandatory to use the suggested “Last used” values, and you can enter your own settings or ignore this feature completely, but please bear in mind that your results might become unpredictable in such a case.

Override

When you activate “Override”, the “Thickness” and “Length” parameters will be unlocked and you can enter new values. With these new settings it is possible to adjust the simulation to your needs, but normally it is not necessary to perform any changes here. By default, the object properties are calculated automatically. If you are not sure whether you should apply changes or not, please read the subchapter “When Do I Need Characteristic Object Properties?” above for more information.

Thickness

This parameter is related to the scene’s objects thickness. Under “Last used” you can see the values the solver used during the last simulation. To make the solver work with a fixed value, enter a new value. We recommend using the associated “Last used” value, but you can enter any other value that suits your needs.

Length

The mode of operation is exactly the same as with “Thickness” and describes the scene’s characteristic object length.