Module: Point Cloud View ()

Description:

This module visualizes data objects of type Point Cloud. The vertices of the point cloud may be rendered using semi-transparent points or using spheres. Both points and spheres may be colored according to any data variable defined in the point cloud. Vertices of the point cloud may be selected or deselected by drawing a contour in the viewer window or by specifying an arithmetic filter expression. Finally, it is possible to display bonds between neighboring points. This is useful, for example, if the points represent atoms in a crystal lattice.

In spheres mode (see below) individual points may be deselected by shift-clicking them. Clicking them without the shift key pressed causes their ID to be printed in the console window.

Connections:

Data
The point cloud to be visualized.

Colormap
The colormap used for pseudo-coloring. The alpha channel of the colormap will be correctly taken into account unless the option opaque has been selected. However, note that many default colormaps are completely opaque. In this case, use the colormap editor to make them transparent.

Ports:

Color

An option menu containing all data variables which can be used for pseudo-coloring. The data variables' symbols are displayed in brackets following the names.

Options

The following options can be set:

Spheres activates the spheres mode. If this mode is active, each selected vertex is represented by a little sphere. For large numbers of points a significant amount of time may be required each time new colors are set. By default, the spheres mode is deactivated. Instead, simple points are rendered. The point size is constant regardless of the distance of a point from the camera.

Opaque influences the way point primitives are drawn. By default, anti-aliased semi-transparent points are rendered. If the opaque option is set, transparencies will be ignored. Opaque rendering is faster but gives less attractive results. In addition, you can't hide certain points by making them more transparent.

Bonds enables the display of bonds between neighboring points. If necessary, connectivity information is computed automatically. This may take some time, especially for large data sets.

Point Size

Specifies the point size in pixels. Only visible if point mode is activated, i.e., if no spheres are shown.

Sphere Scale

Allows you to adjust the size of spheres shown if option spheres has been selected. The default sphere radius is computed from the bounding box of the data set. If option scale spheres is enabled, the size is computed as the data variable selected in scale data multiplied by sphere scale.

Action

The Export button creates a new point cloud containing all selected points of the input point cloud together with the corresponding data variables.

After you press the Select button, you can draw a contour in the viewer window in order to deselect certain points. By default, all points inside the contour are deselected. If you keep the Ctrl key pressed down when starting to draw the contour, all points outside the contour are deselected. Using the Alt key allows you to define straight-line segments. In order to be visible, a point must pass the filter test (see above) and the contour selection test. Both options are independent of each other, i.e., if you change the filter, the current contour selection remains valid.

The Reset button resets contour selection mode. All points passing the filter test become visible.

The Undo button undoes the effect of the last interactive contour selection operation.

Filter

Filter

Switch ON this port causes a text field to be shown, which can be used to specify an arithmetic expression for selecting a subset of points.

Expression

This port allows you specify an arithmetic filter expression. The filter expression is evaluated for every point. Only points for which a non-zero result is obtained are drawn. The filter expression may contain any arithmetic and logical operator defined in the C programming language. All symbols listed in the color menu may be used in the filter expression. In addition, the symbols x, y, and z are defined. These symbols indicate the coordinates of a 3D point. For example, to select all points with positive x-coordinates and with an energy.

Scale Spheres

Scale Spheres

Switch ON this port to enable scaling of spheres by a data variable. The data variables' symbols are displayed in brackets following the names.

Scale Data

Selects the data variable used for scaling spheres. This port is visible if option spheres and option scale spheres are enabled.

Commands:

setBondColor <color>
Specifies the color used for drawing bonds between neighboring points. The color may be specified by either an RGB triple in the range 0...1 or by a common X11 color name, e.g., red or blue.

setBondWidth <width>
This command allows you to change the width of the lines representing the bonds between neighboring points. By default, lines are drawn one pixel wide.