HYM - Filters

Filters are an important method for influencing the final look of a mesh. With filters it is possible to eliminate rounded borders, create thinner or thicker areas and give the mesh a more vivid appearance. The "Filters" section is subdivided into two parts: one section provides parameters that have been particularly developed for this mesh type to catch all the fine details from grid fluids. The other part contains global filters – they are exactly the same as in the "Particle Mesh" tool and are very fast. By default, the Hybrido-specific filters are active and we recommend using them instead of the settings of the “Global filter” section. The parameters of the "Filters" panel support the "Interactive Meshing" feature.

When you take a look at a grid fluid simulation (without secondary elements) you will recognize areas with splashes and fine structures and a larger main body of fluid with less detail. This differentiation is very important, because with the following parameters it is possible to filter these areas individually. You can even adjust the “ratio” between splashes and the core fluid using separate threshold values. You should create some test meshes in any case, before you decide to mesh the entire simulation.

Please read the introduction to the “Hybrido Mesh” engine, because there you will find essential information about how to configure and adjust the filters. To get there, click here.

Splash thinning filter

If this parameter is active, you will be able to control the amount of filtering for the splashy parts of the grid fluid simulation. Please read the “Splash thinning” section in the introduction before you start. There you will find important information about how to use this filter and its associated parameter.

@ splash threshold

Each mesh vertex carries a value that defines whether it is considered a splash or not: 0 means that the vertex does not have any splash attributes and 1 has full splash characteristics. With “@ splash threshold” you can determine when the splash thinning filter should start working and all vertices with values below the given value will be ignored.

@ thinning size

This parameter accepts values between 0 and 1. It is used to scale the thinning effect and good values are close to the particles' radius values of the used grid fluid in splash areas.

Core smoothing filter

To smooth and flatten the core fluid areas, set this option to “Yes” and unlock the associated parameters. Before you start, we recommend reading the “Core smoothing” chapter in the introduction.

@ core threshold

The mode of operation is very similar to “@ splash threshold” and here, a range between 0 and 1 is used. Each mesh vertex has a core-attribute value. With 0, the vertex does not have any core properties, and with 1 it is considered a “full” core vertex. The core smoothing filter will not be applied to points with values smaller than the given threshold. Vertices with values equal or greater than “@ core threshold” will receive an appropriate amount of smoothing.

@ smoothing steps

If you have already worked with the “Particle Mesh's” filter then you should be familiar with this parameter, because it works exactly as the “@ Steps” value: higher settings create sharper and thinner fluid borders. The number of steps also depends on the mesh's resolution and with higher polygon counts (= small “@ polygon size” values) you have to increase this value. For high-resolution meshes, values between 100 and 150 are sufficient.

Global filter

By default, this option is set to “No”, because we recommend using the core smoothing and splash thinning filters instead. If you decide to apply the global filters, choose “Yes” to unlock the associated parameters.

@ thinning

This filter affects the entire mesh, not just particular areas as, for example the Hybrido mesh engine's “Splash thinning filter” option. The effect is that all areas of the mesh become thinner and create the impression of a mesh with a higher resolution. “@ thinning” is very fast and gives great results. Valid values range between 0 (no thinning) to 1 (maximum). We recommend low settings between 0.1 and 0.3.

@ relaxation

This type stretches and sharpens the mesh’s edges and gives you a much more natural look. The result is a more watery and realistic appearance. “@ Relaxation” helps you to get quality meshes even from low resolution emitters. The default value is a very good starting point and it is very likely that you will not have to alter it at all. “@ Relaxation” is very sensitive, so instead of changing the filter’s strength it is often better to lower or raise "@ Steps". Though “@ Relaxation” is very effective, it has limits: emitters with just a few hundred or thousand particles are not really suited to create a perfect mesh – even with filtering.

“@ Relaxation” should also be used with care in terms of creating a believable fluid. An overdone effect can lead to very sharp and unnatural edges, and the entire mesh starts shrinking. The higher the settings, the more details get lost. Of course, this is sometimes wanted – for example for a liquid metal look one would expect from mercury or similar substances with high surface tension. Also sponge-like tissues are a very nice field of application for high “@ Steps” settings and the “@ Relaxation” filter. Higher “@ Relaxation” values should be compensated with lower “@ Steps” settings.

@ tension

If you can see unwanted high frequency structures on your mesh, then it is a good idea to activate this filter type. “@ tension” flattens the mesh surface and removes these artefacts. Similar to “@ relaxation”, this type is also very sensitive and strongly depends on the according “@ steps” settings. Normally, high-frequency patterns do not occur very often, so the “@ tension” filter is rarely used.

@ steps

Each filter is affected by this parameter. Higher settings strengthen only the influence of “@ relaxation” and “@ tension”, and they can lead to completely over-filtered meshes. Values above approximately 120 may produce unrealistic results, unless you really want to achieve a certain effect. Another issue is that very high settings will reduce the amount of details. A range between 8 and 32 seems to work best for most applications.