Tracing Single Spline Paths Through a CFD Velocity Field

You can generate one or more splines by advecting specific positions through the velocity field of a CFD simulation.

1. Import a Simulation CFD file as described here.
2. Add a helper object, such as a point or dummy helper.
3. Move the helper to the position from which you want to start the spline.
4. Choose Create > AEC Objects > CFD Visualization > MCG Create CFD Spline.
5. When prompted, first pick the CFDImportData object and then pick the helper.

   A CFDSplineNode object is created in the scene.

6. On the Modify panel, adjust the CFDSplineNode's Spline Parameters as desired. The length of the spline is controlled by a combination of Spline Vertices and Field Sampling.
7. You can continue to adjust the helper's position as desired.
8. If you want to save out a spline, click Bake Spline. This creates a separate editable spline that is no longer connected to the helper.

   You can continue to move the helper, adjust the settings, and save out more splines.

Spline Parameters

Sim CFD Data

(CFD Points)

Click to pick a different CFDImportData object in the scene.

Refresh Data

Click in case the CFDSplineNode object does not update properly when you make changes.

Spline Controls

(Spline Origin Helper)

Click to pick a different CFDImportData object in the scene.

Spline Vertices

The number of vertices in the generated spline.

Interpolation Settings

Nb. Vertices

The number of nearby CFD data points to sample per vertex.

Smoothing

Controls the weighting of the nearby CFD data points: 1.0 gives a linear falloff, 2.0 gives an inverse-square falloff, and so on.

Field Sampling

A divisor for the velocity vector used to extend the spline at each step. Values above 1.0 result in shorter, more accurate segments between spline vertices, while values between 1.0 and 0.0 result in longer segments.

Material Controls

Controls the material ID assigned to each spline segment. By default, a Multi/Sub-Object material is applied to the spline, and successive spline segments can cycle through the sub-materials based on the material ID.

Material count

Controls the number of sub-materials that successive splines cycle through. If this value is 1 or less, all segments use the first sub-material; if it is 2, the segments cycle through the first two sub-materials; and so on.

Material animation

Offsets the material cycle by the specified number of places. You can animate this value to move the sub-materials along the spline.