Module: Splats ()

Description:

This module visualizes scalar fields defined on tetrahedral grids using a direct volume rendering technique called cell projection splatting. The principle of this method is to display a kind of semi-transparent clouds. The higher the data values the brighter and more opaque these clouds are. Often, meaningful results are obtained if this technique is used in conjunction with a standard Isosurface module.

In order to get correct results for linearly varying functions a special texture mapping technique is applied. On machines where texture mapping is not supported in hardware this might be quite slow. As an alternative untextured splats may be used. However, In this case, the scalar field is assumed to be constant in each tetrahedron. To obtain such a piecewise constant function the vertex values of each tetrahedron are averaged. As a consequence artificial discontinuities might be observed.

Press the Apply button to start the computation.

Connections:

Data [required]
The tetrahedral scalar field to be visualized.

ROI [optional]
Connection to a module defining a region of interest.

Colormap [optional]
The colormap is used for pseudo-coloring the clouds.

Ports:

Alpha Scale

A global factor used to change the overall transparency of the individual splats. Higher values produce denser clouds.

Gamma

This value determines how the function value between the min and max values of port Range will be mapped to opacity and color. If the gamma value is 1 a linear mapping will be used. If the gamma value is smaller than 1 the overall appearance of the cloud gets more opaque. If the gamma value is bigger than 1 the cloud gets more transparent.

Range

Data range. Regions where the function value is below the min value will be completely transparent. Likewise, regions where the function value is above the max value will be opaque.

Interpolation

Lets you select the type of splats being used. Constant enables untextured splats. Linear enables textured splats. The latter setting will be able to correctly display linearly varying scalar fields.

Optical Model

Switches between different optical models: only light emission or emissive and absorptive light model or absorbing light only.

Colormap

In case a colormap is connected to the splats module, this colormap will be shown here. If no colormap is connected to the module the port's default color is used. To change this color, click into the color bar with the left mouse button. This will bring up the color selection dialog. To connect the port to a colormap, use the popup menu under the right mouse button. See also Colormap.

Commands:

setColor <color>

Lets you define the base color of the volume rendered clouds. On default an orange color will be used (0.8 0.6 0.1). The color may be specified by either an RGB triple in range 0...1 or by a common X11 color name, e.g., green.