Optotrak Motion Tracking System

Using NDI Software

utilities > query system camera c3 - 3 sensors

to get feel for range of trackable space, green light = marker seen, vs. red light new experiment : next > next > ports (front of box) + how many markers 1 + 6 markers

cal frequency = 200hz for raipd reaching namicmaker power frequency- leave alone

finish

play around with markers to test where your capture volume is

Optotrack Matlab Code

optotrack matlab code, functions for interfacing with c api (not on cd, given by some guy) more in optomfiles, not more frequently used

runshapempt.m

optotrak_init, written by craig, set up (each subject)

create local coofdinate frame: dynamic and static

looking at only one marker (frontmost);

next ask for 3 points: 0,0 then x-axis (not amount, just positive x) then y (positive)

datagetnext3d- gets next available position of marker (must initialize pdtadest as single)- note: opto deals in single precision, matlab likes to work in double note: opto calls any missing value as high negative number, can call "nan" in matlab

setup opto activates markers, so then deactivate

T_glob_loc from global opto coordinate frame to local table coordinate frame

make folder for handling raw opto data (idiosyncratic to craig's subject folder structure)

realtime in actual experiment: line 50 - 88

line 375 0 make sure in right folder - activate

start position code - 379-399 get location, change to double from single, tranform it, then use it (1:3) = only one marker xyz, (4:6) -

data buffer start buffers on separate opto box

if want to use real time marker in matlab- can use velocity to see if moved - detectvelonset.m function, stores 4 samples at a time and calculates whether velocity exceeds threshold

end of trial: make sure finished writing buffer- spooling finished? then deactivate markers

analyze reach- for analysis, filter, fill in missing data

SUMMARY

beginning of experiment:

• initialize
• setup frame
• setup opto

trial loop:

• activate
• do stuff
• deactivate