This section is intended as short road-map though TEMPO source code files. TEMPO code is pretty much populated with comments, and, as with any other open source project, source code is ultimate reference. Also, Doxygen format is used for commenting TEMPO classes interfaces, so Doxygen tool could be employed along with tempo.cfg Doxygen configuration file in TEMPO distribution root directory to generate documentation for these interfaces in various formats.
Source code files are grouped in src subdirectory of TEMPO distribution. Subdirectory data contains files with face and scalp models, as well as file with electrode names and positions and sample EDF file. Subdirectory manual contain help files (what you are reading now) in HTML format. Subdirectory resources contains artwork (icon files). Subdirectory tmp is where compilation artifacts are stored (note however that executable is generated in TEMPO distribution root directory. File tempo.pro is Qt project file. Other files in TEMPO distribution root directory are rather standard files for any open source project.
TEMPO is written in C++ programming language, using OpenGL library for 3D graphics and Qt toolkit for graphical user interface. Thus, familiarity with these technologies is necessary in order to be able to understand source code.
When examining src subdirectory, one should start with vector.*, color.*, bounding_box.*, vertex.*, material.* and triangle.* files. These files contain definition of simple data structures to be used for constructing geometry model.
One should proceed with object.* files then. These files contain definition of data structure and accompanying operations for geometry model. Two operations related to this data structure are especially important: creating model from given data file and rendering model using OpenGL routines. Input format for object geometry is simple ASCII format; input file contains arrays of vertices, normals, materials and triangles. Each array is preceded by number designating array length. Array elements are groups of numbers corresponding to fields of data structures mentioned above. Subdirectory data of TEMPO distribution contains files face.mo and scalp.mo with face and scalp models in above format. OpenGL code rendering object model is (as emphasized in comments) for simplicity left without any optimization (nevertheless, this code works pretty fast even on software-only OpenGL implementations).
Files scene.* contain definition of data structure and accompanying operations for scene object. Scene object contains instances of face and scalp objects. Visualization created by TEMPO is pretty generic in the sense that this code could be utilized for any kind of visualization where some parts of scene are color coded from some interpolated values and other parts of scene rendered as is. Thus, instead of "face" and "scalp", terms "not mapped" and "mapped" are utilized through TEMPO code. Also, term "sensor" is utilized later instead of term "electrode". It would be actually very easy to utilize TEMPO rendering code to create visualization of say interpolated statical load across the bridge given measured loads in some points; but that is unrelated story.
Geometry related parts of TEMPO code are completed with quaternion.* and rotation.* files. These files contain definition of rotation data structures and corresponding operations. Quaternions are used to calculate cumulative scene rotation after user interaction with mouse.
Files exception.* contain definition of exceptions that could be thrown from TEMPO for error handling purposes.
Signal processing related parts of TEMPO code begin with fft.* files. These files contain implementation of FFT procedure, together with caching of auxiliary data for faster execution.
Files sensors.* contain data structure definition for electrodes ("sensors" in TEMPO terminology, as above explained) names and positions. These information are read from file in simple ASCII format: first line of file contains number of electrodes, and then follows lines with electrode information where length of electrode name is given first, then electrode name between quotation marks and finally electrode positions (in same coordinate system as face and scalp models are given). Subdirectory data of TEMPO distribution contains file 10_10.ms with corresponding information for electrode arrangement according to 10-10 and 10-20 international standards.
Reading of input EDF file and calculating EEG scores is distributed between input.* and signal.* files. Former files contain definition of data structure and operations to read EDF file header and to calculate array of EEG score values given needed set of samples on each electrode. Later files contain definition of data structure representing individual EEG channel and operations to read corresponding signal header from EDF file and provide set of signal samples of given length at given position in EDF file (this operation is used by above mentioned function from input.cpp file calculating array of EEG score values). Important to note is that function from input.cpp file reading EDF header is also looking at signal headers and comparing signal names to names known to above discussed sensors object (an instance of this object is passed to this function). Thus, signal objects are created only for channels from EDF file whose names corresponds to names of electrodes known to TEMPO.
Mapping of score values to colors is encapsulated in interpolation object, defined in interpolation.* files. Weight coefficients for each scalp vertex according to vertex distance from set of nearest electrodes are calculated during initialization of this object and used later to actually perform interpolation. Mapping of values to color pallette is also defined here.
Two simple Qt widgets are defined in gradient_widget.* and visualization_widget.* files respectively. First widget is drawing color legend and is later instantiated in legend frame of TEMPO main window. Second widget is actually showing OpenGL rendering and is later instanced in left half of TEMPO main window.
Set of files info_widget.*, score_widget.*, legend_widget.* and time_widget.* contain code for creating graphical user interface and handling appropriate events for corresponding frames on right half of TEMPO main window. This code is bulky, but is rather simple actually.
Files main_widget.* contain code for TEMPO application main widget, that is uniting highest level components of above together. Files manual_widget.* contain implementation of simple browser for TEMPO help files.
Finally, main.cpp is file containing program main() function
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