Module: Point Cloud Difference ()

Description:

This module displays displacement vectors between corresponding points in two different data objects of type Point Cloud. The displacement vectors may be colored according to their lengths or according to any data variable defined in one of the input point clouds. Like in the Point Cloud View module, subsets of points may be selected by drawing a contour in the viewer window or by specifying an arithmetic filter expression.

Connections:

Data
The first point cloud.

Data2
The second point cloud. Initially, this port will not be connected to any data set. In order to use the module you have to establish a connection manually by activating the popup menu over the white square on the left side of the module's icon.

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 that can be used for pseudo-coloring. The data variables' symbols are displayed in brackets after the names.

Options

The following two options can be set:

Filter causes a text field to be shown, which can be used to define an arithmetic expression for selecting a subset of points.

Opaque influences the way how the displacement vectors are drawn. By default, anti-aliased semi-transparent lines are rendered. If the opaque option is set, transparencies will be ignored. Opaque rendering is faster but gives less nice results. In addition, you can't suppress certain lines my making them more transparent.

Filter

This port allows you specify an arithmetic filter expression. The filter expression is evaluated for every pair of points. A displacement vector will only be drawn if for both points a non-zero result is obtained. 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. For example, in order select all vectors shorter than 0.2 and with an energy larger than -4 use .

Action

The button labeled Export A creates a new point cloud containing all selected points of the first input point cloud together with the corresponding data variables. Similarly, the button labeled Export B creates a new point cloud containing all selected points of the second input point cloud.

After pressing the Select button you may 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.

The Reset button causes all points matching the filter expression to be shown again.

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

Commands:

setLineWidth <width>
Specifies the width of the displacement vectors. By default, the vectors are one pixel wide.

setLineSmooth {0|1}
Enables or disables line smoothing. By default, smoothing is on unless the opaque option has been selected.