Technical Specs

Internal acquisition
Camera image
Fig. 6.1.2: Images are internally always captured with 25 Hz. The fps parameter determines how many of them
are sent as camera images via GigE Vision.
exp
_
auto (Exposure Auto or Manual) This value can be set to 1 for auto-exposure mode, or to 0 for manual
exposure mode. In manual exposure mode, the chosen exposure time is kept, even if the images are overex-
posed or underexposed. In auto-exposure mode, the exposure time and gain factor is chosen automatically
to correctly expose the image. The last automatically determined exposure and gain values are set into
exp
_
value and gain
_
value when switching auto-exposure off.
exp
_
max (Max Exposure) This value is the maximal exposure time in auto-exposure mode in seconds. In the Web
GUI, this exposure time can be conveniently entered in milliseconds. The actual exposure time is adjusted
automatically so that the images are exposed correctly. If the maximum exposure time is reached, but the
images are still underexposed, the rc_visard stepwise increases the gain to increase the images’ brightness.
Limiting the exposure time is useful for avoiding or reducing motion blur during fast movements. However,
higher gain introduces noise into the image. The best trade-off depends on the application.
exp
_
offset
_
x, exp
_
offset
_
y, exp
_
width, exp
_
height (Exposure Region) These values define a rectangular
region in the left rectified image for limiting the area used for computing the auto exposure. The exposure
time and gain factor of both images are chosen to optimally expose the defined region. This can lead to
over- or underexposure of image parts outside the defined region. If either the width or height is 0, then the
whole left and right images are considered by the auto exposure function. This is the default.
The region is visualized in the Web GUI by a rectangle in the left rectified image. It can be defined using
the sliders or by selecting it in the image after pressing the button Select Region in Image.
exp
_
value (Exposure) This value is the exposure time in manual exposure mode in seconds. This exposure time
is kept constant even if the images are underexposed. In the Web GUI, this exposure time can be entered in
milliseconds for convenience.
gain
_
value (Gain) This value is the gain factor in decibel that can be set in manual exposure mode. Higher gain
factors reduce the required exposure time but introduce noise.
wb
_
auto (White Balance Auto or Manual) This value can be set to 1 for automatic white balancing or 0 for
manually setting the ratio between the colors using wb
_
ratio
_
red and wb
_
ratio
_
blue. The last automat-
ically determined ratios are set into wb
_
ratio
_
red and wb
_
ratio
_
blue when switching automatic white
balancing off. White balancing is without function for monochrome cameras.
wb
_
ratio
_
red and wb
_
ratio
_
blue (Red | Green and Blue | Green) These values are used to set red to green
and blue to green ratios for manual white balance. White balancing is without function for monochrome
cameras.
These parameters are also available over the GenICam interface with slightly different names and partly with
different units or data types (see GigE Vision 2.0/GenICam image interface, Section 8.1).
6.1.4 Services
The stereo camera component offers the following services for persisting and restoring parameter settings.
save
_
parameters (Save) With this service call, the stereo camera component’s current parameter settings will
be made persistent to the rc_visard. That is, these values are applied even after reboot.
This service requires no arguments.
This service returns no response.
reset
_
defaults (Reset) Restores and applies the default values for this component’s parameters (“factory re-
set”).
6.1. Stereo camera 32