Concepts

This page is compact list of concepts and glossary used in FAST.

• Process object - A pipeline object (PO) which performs processing on zero or more input data and generates zero or more output data.
• Pipeline - A set of process objects connected together to form an execution graph.
• Renderer - A process object which draws the input data on screen using OpenGL shaders
• Importer - A process object which imports some data, for instance reading an image from disk. Usually have zero input ports, and one output port.
• Exporter - A process object which exports some data, for instance storing an image to disk. Usually have one input port, and zero output ports.
• Streamer - A special process object which inherits from Streamer, and generates data asynchronously. This can for instance be streaming data from an ultrasound scanner in real-time or from disk.
• View - An object that represents a scene/viewport. It has a list of renderers, which it calls upon to draw its scene sequentially in order. It inherits from the QGLWidget which is an Qt OpenGL rendering widget, and may therefore be used as a regular Qt widget.
• Text pipeline - A pipeline defined in a text file, uses the extension .fpl (fast pipeline). It can be executed with the runPipeline executable.
• Output port - A process object may have 0 or more output ports which provides data when executed. Identified by an unsigned integer starting at 0.
• Data object - Every data object that flows over pipeline connections inherit from the FAST class DataObject. These objects are meant to represents data which can be stored on multiple processors and in different storage formats/memory types.
• Access object - Since data objects in FAST can exist on multiple processors and in different memory, data is accessed through access objects which in general uses the RAII (resource allocation is initialization) concept. You have to specify whether you want READ or READ_WRITE access to data. If a thread already has write access to this data object, the access request will block until the writing access object is done.
• Execution order - When you call the update() method on a process object you will potentially execute the entire pipeline ending at this process object. Update will first call update() on every input connection of the current process object in a recursive manner. After its input connections are finished updating the process object will call execute() if the following conditions hold:
  • One of its input connections have new/updated data OR
  • The process object is marked as modified (e.g. a parameter has changed) OR
  • One of its input connection is a Streamer AND that streamer has not sent a data object with the last frame flag set