Northern Digital Polaris Vicra User Manual page 68

Setting the Infrared Light Sensitivity
Choosing a Sensitivity Level
Choose a sensitivity level of 5, 6 or 7 if:
• If the "IR Interference" flag in the Port Status flags is on persistently
AND
• tools don't track
AND
• re-arranging the scene doesn't help.
Choose a sensitivity level of 3, 2 or 1 if:
• If a tool doesn't track
AND
• all markers are clearly in view AND clean
AND
• no other error flags are giving any indication for why the tool is not tracking
(NDI experience shows that there should not be any reason for going to a level lower than 4.)
Note
The sensitivity levels do NOT change the way centroid extraction is performed and therefore can NOT solve
tracking problems with tools embedded in background IR. Sensitivity level adjustment only helps when tool and
background IR are in different physical locations.
Use the default sensitivity level 4 unless the system is experiencing interference from background
IR light. If the system is experiencing such interference, check the environment for causes (for
example, reflections). If it is not possible to eliminate the source of the background IR light, then
start with a low sensitivity level and increase the level until the tools track reliably.
The system may actually be tracking a tool even when the tool's IR interference flag is on. You
should still increase the sensitivity level, since the behaviour of the system in this case is dependent
on the setup. (For example, moving the tool to another part of the measurement volume may prevent
it from being tracked properly.)
Changing the Sensitivity Level
You can change the IR sensitivity of the Polaris Vicra System using either NDI ToolBox or the
SENSEL command.
The NDI ToolBox software can be used to select a sensitivity level, and to program a sensitivity
level as the default setting in the Position Sensor memory.
The SENSEL command is used to temporarily select a sensitivity level. The level set using the
SENSEL command persists until a RESET or INIT command is issued. The SENSEL command can
also be used to query the currently active level. For more information on the SENSEL command, see
the "Polaris Application Program Interface Guide".
56 Polaris Vicra User Guide - Revision 2