View_AB

 

VIEW_AB.EXE allows to display and analyse the contents of rawdata files (V*.AB).

All Operations like opening files, certain display modes etc. could be done right within the program.

 

VIEW_AB.EXE will quit when <ESC> is pressed. Alternatevely the program quits when clicking the “Close”-option within the File-Menu.

 

The Menu-Option “Rawdat Parameter” controls the behaviour of the program.

There you can start and stop displaying raw-data and you can also choose the

appropriate kind of view.

 

 

Display and analysis of raw data

 

1. Asynchronous display

 

 

The asynchronous raw data display is called by starting RAWDAT with the Menu-Option “Asynchrone view” (could be found in Rawdat Parameter). The two data streams of the two cameras are visualized in the left and the right half of the

screen (upper system = cam A = front view = left half of screen, lower system = cam B = side view = right half). The two displays are not synchronized.

The x-axes represent the 512 pixel of each of the cameras. The y-axis represents a time scale, one line corresponds to around 29 microseconds (at a line scan frequency of approx. 34.5 kHz). The full height of the picture corresponds to around 1800 lines, i.e. approx. 52 milliseconds. Periods with no data are omitted in the display, a horizontal line indicates such a time jump.

After having detected shadowed areas within one line it is the next task of data

preprocessing to identify valid elements in each of the cameras data streams. The result of this procedure is visualized in this display. Elements recognized as valid are shown in red resp. blue colour. Invalid elements are shown in grey colour.

 

 

 

 

 

 

 

Fig. 1   Asynchronous View

 

 

 

 

2.  Synchronous display

 

 

The synchronous raw data display is called by invoking RAWDAT with with the Menu-Option “Synchrone view” (could be found in Rawdat Parameters).

The two data streams of the two cameras are visualized in the left and the right half of the screen (upper system = cam A = front view = left half, lower system = cam B = side view = right half). The two displays are synchronized. The x-axes represent the 512 pixel of each of the cameras. The y-axis represents a time scale, one line corresponds to around 29 microseconds (at a line scan frequency of approx. 34.5 kHz). Periods with no data are omitted in the display, a horizontal line indicates such a time jump.

Elements discarded as invalid in the first preprocessing step are not displayed here.

As the next task elements of the two cameras have to be linked to pairs. If such a pair is considered to be a valid one, it is displayed in red and blue colour. In case of an invalid pair (e.g. big front view element, small side view element) the colour is grey. Particles outside the intersecting measuring area are seen in only one camera, they are displayed in grey color.

Valid pairs found in here go into the hydrometeor data file (V*.HYD) which may be displayed by OFFL.

 

Fig. 2 Synchronous View

 

 

3. Access to the raw data

The user may access the raw data files. A full sample how to decompress the file format is given in the subdirectory TYPE_AB. TYPE_AB has been prepared to be compiled by the Microsoft Visual C++-compiler (Version 6.0 and higher).