Within the concept of MeVisLab the basic entities we are working with are graphical representations of modules with their specific functions for image processing, image visualization, and image interaction.

The three basic module types (ML, Inventor and macro) are distinguished by their colors:

Table 2.1. Module Types

Type	Look	Characteristics
ML Module (blue)		Page-based, demand-driven processing of voxels
Open Inventor Modules (green)		Visual scene graphs (3D); naming convention: all modules starting with “So” (for scene object)
Macro Module (brown)		Combination of other module types, allowing implementing hierarchies and scripted interaction

Most modules have connectors which are displayed on the module. These represent the inputs (bottom) and outputs (top) of modules.

In MeVisLab, three types of connectors are defined.

	Note
	In principle, every module type can have any kind of connector.

Table 2.2. Connectors

Look	Shape	Definition
	triangle	ML images
	half-circle	Inventor scene
	square	Base objects: pointers to data structures

By connecting these connectors and therefore establishing a so-called data connection, image data, or Open Inventor information is transported from one module to one or more others.

Besides connecting connectors, basically any field of modules can be connected to other compatible fields of modules with a parameter connection.

	Note
	A special case are Inventor engine fields; they have no value representation themselves unless connected to a fitting destination field. See Section 27.4, “Connecting Inventor Engines to ML Modules” for more details.

Table 2.3. Connections

Type	Look	Characteristics
Data connections (connector connections)		The direct connection between connectors. Depending on which connectors are involved, the connection is rendered in a different color: blue for ML, green for Open Inventor, brown for Base.
Parameter connections (field connections)		Connections created by connecting parameter fields within or between modules

	Tip
	For more display options, see the MeVisLab Reference Manual, chapter “Modules and Networks”.