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

Opto Analysis

each subject has own folder with .mat output file (parameters, trial conditions), and also opto folder with raw data (one file per trial) opto reach analysis gets placed back into the .mat file (data_struct.fdaMat)

analyze reach, loads in the data and calls other functions

fopen(filename) function that reads in a byte at a time, read in header, then read in data function

rawdata matrix created, 6x3x400 400=data points(samples), 3=xyz, 6=markers

note- bad values not =0, but rather -3e28 -- so first convert these to NaN

transform coordinate frame (using .mat data file which has transform info)

make each marker a cell, 6 cells, each with 3 xyz coordinates x 400 samples (200 per second over the 2 seconds)

raw data has to be edited so that one marker can fill in gaps from other marker, then interpolation of missing samples