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Run-time post-processing

The runTimePostProcessing function object generates images by assembling and compositing scene objects, typically produced via function objects.

  • Generate a static image, or a sequence of images
  • Render points, lines and surfaces
  • Optional scalar bar
  • Perspective and parallel camera modes
  • Various colour maps

This object has a dependency on the VTK libraries

Usage​

The runTimePostProcessing function object is specified using multiple sub-dictionaries that describe the desired output, camera and scene object settings:

runTimePostPro1
{
    type            runTimePostProcessing;
    libs            ("librunTimePostProcessing.so");

    // Image properties
    output
    {
        ...
    }

    // Visualisation properties
    camera
    {
        ...
    }

    // Default colours
    colours
    {
        ...
    }


    // Scene objects

    lines
    {
        ...
    }

    surfaces
    {
        ...
    }

    text
    {
        ...
    }
}

output​

The output sub-dictionary describes properties of the output png file

output
{
    name            image;
    width           2000;
    height          1200;
}

camera​

Basic operation of a static camera comprises:

camera
{
    // Parallel projection flag
    parallelProjection  no;

    // Camera geometry
    focalPoint      (1.2 1.1 0.2);
    up              (0 0 1);
    position        (3.6 5.1 -1.3);


    // Optional properties

    // Restrict the view to a clip box
    clipBox         (-0.2 -0.2 0)(1.65 0.2 1.25);
}

Optionally, the camera can move. Each of the camera geometry controls is a Foam::Function1 type, and can be set to vary as a function of scene time using e.g. tabulated, polynomial, sinusoidal profiles etc. The scene time is defined as a linear function between zero and one.

An example using tabulated entries is given by:

camera
{
    // Parallel projection flag
    parallelProjection  no;

    // Camera geometry
    focalPoint      (1.2 1.1 0.2);
    up              (0 0 1);
    position        (3.6 5.1 -1.3);


    // Optional properties

    // If camera is moving, optionally provide start and end times
    // Note: specified in scene time in range 0-1
    startPosition    0.2;
    endPosition      0.75;

    // Total number of frames to generate
    nFrameTotal      20;
}

colours​

The colours sub-dictionary defines the set of default colours to employ for the background, and scene objects when the colourBy entry is set to colour.

colours
{
    background      (1 1 1);

    text            (0 0 0);
    edge            (1 0 0);
    surface         (0.5 0.5 0.5);
    line            (1 0 0);


    // Optional

    // Set a second background colour to produce a graded background
    background2     (0 0 1);
}

Scene objects​

Scene objects provide the main focus of the image, e.g. lines, surfaces and text. All objects have a visible property to optionally hide the object.

lines​

The lines sub-dictionary describes line-based data, e.g. the output from stream lines. Valid line types include:

  • functionObjectLine: line based data produced by a function object
lines
{
    streamline
    {
        type            functionObjectLine;
        functionObject  streamLines;
        representation  tube;
        visible         yes;
        tubeRadius      0.01;
        colourBy        field;
        field           U;
        range           (0 20);
        opacity         1;
    }
}

Sample output​

  • Portable Network Graphic (PNG) images

Further information​

Related:

API:

Example usage:

History: Introduced in version v3.0+