Module: Isocontour Slice ()

Description:

This module computes isolines and their annotations for an arbitrary 3D scalar field on a 2D cutting plane. The plane itself is defined by another module which must be connected to port Module. Isocontour Slice are computed using two different algorithms depending on the type of the incoming scalar field. If the scalar field is defined on a tetrahedral grid then all tetrahedra intersecting the plane are determined first. The straight isoline segments are generated for these tetrahedra according to the requested threshold values. If the incoming scalar field is not a tetrahedral one then the field is sampled on a regular 2D raster first. Each rectangular cell of the raster is then checked for isolines. Note, that this approach may lead to artifacts if the sampling density is too low.

To execute a demo script illustrating the isoline module click here.

Connections:

Data [required]
Scalar field for which isolines are to be computed.

Module [optional]
Module defining cutting plane used for isoline computation.

Colormap [optional]
Colormap used for pseudo-coloring. If no colormap is connected all isolines have equal color. This port is hidden if the Data port is connected to an Unstructured Model Field. In that case, the colormap of the data set is used for the display.

Ports:

Spacing

Control how isoline thresholds are being defined. In uniform a certain number of isovalues are distributed equidistantly within a user-defined interval. In explicit mode the threshold for each isoline has to be set manually.

Values

In uniform mode this port contains three text fields allowing the user to define the lower and upper bound of the isoline interval as well as the number of isolines being computed in this interval.

Values

In explicit mode an arbitrary number of blank-separated threshold values can be defined in this text field. For each threshold a corresponding isoline is displayed.

Colormap

Port to select a colormap. See Connections section.

Annotate

Annotate

When Annotate is ON,annotations are drawn on isolines, and ports Text Alignment, Font, Text Scale, Text spacing and Annotate Every ports are enabled below.

Text Alignment

Indicates how annotations are drawn on isolines. If choice is tangential path then annotations are drawn according the tangent line of isolines. Camera aligned means that annotations are drawn always facing the camera. If the contour clip is checked then the contour below annotations is erased.

Font

Select the font and color of annotations of contour lines. The font size is a multiplicative factor of the domain size. The font size impacts annotations position and number of annotations. As much as possible, the annotations are placed to avoid crossing mesh lines or mesh contours.

Text Scale

Font size factor of annotations of contour lines. It's a multiplicative factor of font size. Useful when using projection, a heuristic is applied to keep a ratio font size / mesh size. Sometimes to obtain a better effect the default factor must be customized.

Text Spacing

Curvilinear distance between two annotations of a same contour line. It is a multiplicative factor of the domain size.

Annotate every

The Annotate every [number] line defines the period of major contour lines. Only major contour lines can be annotated. The second part of Annotate every , starting with line [number] defines the first major contour line.

Advanced

Quality

Port quality contains four options. There are 3 default Qualities (low/medium/high) which compute automatically the resolution depending on the number of voxels along each axis in the local plan. With custom, you can choose the resolution yourself.

This port will be hidden if the resolution can't be computed (depending on connected data and connected planar module).

If the connected planar module is a Slice, options of this port will be the same that options of the port sampling in the slice.

Parameters

The resolution value determines the resolution of the sampling raster used for computing isolines. This parameter is ignored if the incoming scalar field is defined on a tetrahedral grid and the Resample option is off. The second input of this port determines the width of the isolines in pixels.

Options

Two toggle buttons are provided. If update min-max is set then the isoline thresholds are automatically reset to some default values whenever the data range of the incoming scalar field changes. The toggle called Resample allows you to compute isolines using the resampling approach even if the incoming scalar field is defined on a tetrahedral grid.