Module: Particle Plot ()

Description:

ParticlePlot is a replacement for the older Cone Plot module. For compatibility reasons the old Cone Plot module is still available.

This module visualizes scalar vector fields by particles (cones) pointing in the direction of the local flow. The placement of particles can be done similar to the distribution modes of the Illuminated Streamlines module. The particles are animated to generate a sequence of objects "walking" through the vector field. An example project can be found at share/demo/basic/HxParticlePlot.hx. ParticlePlot uses Open Inventor render caching. All animation steps are pre-computed and played back by making the appropriate parts of the scene visible. This technique requires little CPU computation but larger amounts of memory and a fast graphics card. Notice that the first pass through the animation may be slow but subsequent render passes speed up. To control the overall speed of the animation use the setRealTimeDuration command of the time slider.

Note that you must press the Apply button for every change in the parameters. Only the objects' Height and Radius are updated without you needing to explicitly press the Apply button.

Connections:

Data [required]
The 3D vector field to be visualized.

ROI [optional]
A connection to a ROI Box module which specifies a rectangular region of interest. The seed points will be restricted to its region of interest.

Shape data [optional]
Supply a custom shape to be replicated instead of the cones. Any geometry displayed in can be used.

Distribution [optional]
An optional scalar field which can be used to control the distribution of seed points.

Color field [optional]
An optional scalar field which, if present, will be used for pseudo-coloring. Often it is useful to create a scalar field from a vector field using the Magnitude module.

Colormap [optional]
The Colormap used to encode the color field. If no color field is connected, the magnitude of the vector field at each position will be used for pseudo-coloring. This port is hidden if the Data or Colorfield port is connected to an Unstructured Model Field. In that case, the colormap of the data set is used for the display.

Animate [optional]
A time slider which controls the currently shown step of the animation. To control the overall speed of the animation use the setRealTimeDuration command of the time slider.

Ports:

Distribute

This port provides an option menu specifying how seed points are distributed inside the seed box. By default, a homogeneous distribution will be used. Alternatively, seed points may be distributed according to the vector field's magnitude or according to the value of the distribution field, if such a field is connected to the module. The Adaptive Histogram Equalization option provides a mixture of homogeneous and proportional seed point distribution.

The regular option distributes the objects at regular intervals in the bounding box using the information in the Resolution port. For this last setting, the length of integration is set initially to 1 in order to restrict the number of cones produced.

Resolution

For proportional and equalized distribute settings, this port specifies the resolution at which the vector field will be sampled. If the regular mode for the distribution is selected, this port will specify the number of objects distributed in the bounding box.

Colormap

A colormap which specifies the pseudo-coloring used. Please note that the maximum magnitude detected is printed out by the module after each Apply button action. See Connections section.

Options

This port specifies the number of traces computed, the number of cones per trace which are displayed at each point in time, and the number of steps of the vector field integration.

Options2

This port specifies the initial step size of the Runge-Kutta solver and the height and radius of the cones. If a shape object is attached to the module, only the height setting will be used to specify its isotropic scaling.

If you want to change the default data range of each of the Options ports, you can use the following Tcl command:
  Particle Plot Options setMinMax 2 0 500
which will for example set the minimum and maximum values of the Length text field to 0 and 500.

Threshold

This port specifies an expression field similar to the one used in Arithmetic. The value x is defined as the magnitude of the vector field evaluated at each position of the field.

Animate

A time slider which controls the currently shown step of the animation. To control the overall speed of the animation use the setRealTimeDuration command of the time slider.

Commands:

createLineSet
Generates a line set object from the current particle trace.

getStepsToBlend
Returns the current number of steps that will be used at the begin and end of each particle trace to blend out the objects.

setStepsToBlend x
Sets the number of steps that will be used at the begin and end of each particle trace to blend out the objects.