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Chapter 4 - DOS Touchscreen Driver and Calibration Utility
Calibration Points Flag (-c)
This flag specifies the Calibration Points:
-c<XLow,XHigh,YLow,YHigh,ZLow,ZHigh>
The coordinates are specified in decimal.
Purpose
Calibration tells ELODEV the position and size of the video image in relation to
the touchscreen. This relationship varies not only between monitors, but also with
monitor adjustment. Only by knowing the position of the image can ELODEV and
the application software locate the user's touch. The need for calibration is
discussed at length in Chapter 2.
How the Calibration Points Are Determined
The ELOCALIB program is typically used to acquire the calibration points and
place them on the ELODEV command line in AUTOEXEC.BAT. (Sometimes an
application will include its own calibration program or procedure. See your
application documentation for details.) ELODEV then uses these calibration
points to map touch coordinates from the controller to screen coordinates.
ELODEV or the application program further maps the screen coordinates into
valid touch zones or on-screen buttons.
Hardware Axis Inversion
The calibration process used by ELOCALIB also forces the default origin to be
the upper-left corner. Because the touchscreen typically has its origin in the lower-
left corner, it is normal for ELOCALIB to indicate the Y (vertical) axis is being
inverted. If the touchscreen is installed on the CRT face rotated 180°, ELOCALIB
will indicate the X (horizontal) axis is being inverted.
Z-Axis Calibration
To insure compatibility, Z-Axis Calibration Points are required even for
controllers that only operate in two dimensions. In this case, any values may be
used for ZLow and ZHigh, such as 0,0 or 1,15.
When using an IntelliTouch controller, the Calibration Range for Z is actually a
sensitivity range. Values of 1,15 or 1,255 are normally used for ZLow,ZHigh,
since these ranges match the values returned by the controller.
This range can be decreased if the application requires fewer levels of Z. Before Z
scaling occurs, the value of Z returned by the controller is pushed within the
Calibration Points. For example, if ZHigh is reduced to 10, all touches harder than
