Microenvironment T racker
(MicroTrac)
MicroTrac
Version 1.0
User Guide
Michael Breen
Email: breen.michael@epa.gov
U.S. Environmental Protection Agency
National Exposure Research Laboratory
Research Triangle Park, NC 27711
EPA Document Number: EPA/600/B-16/207
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Table of Contents
Introduction 1
Installing MicroTrac 1
Running MicroTrac 2
MicroTrac Results 4
MicroTrac Example Run 6
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Introduction
MicroTrac is a classification model that estimates time of day and duration spent in eight
microenvironments (indoors and outdoors at home, work, school; inside vehicles; other
locations) from global positioning system (GPS) data and geocoded building boundaries. The
details of the MicroTrac algorithm are described in the peer-reviewed publication: Breen et al.,
GPS-basedMicroenvironment Tracker (MicroTrac) Model to Estimate Time-Location of
Individuals for Air Pollution Exposure Assessments: Model Evaluation in Central North
Carolina. J Expo Sci Environ Epidemiol. 2014 24:412-420.
MicroTrac is available as a standalone executable, which was developed and compiled using
Matlab (version: R1015a, manufacturer: MathWorks, Natick, MA, USA). All Matlab
functionality required by the model is provided by the MATLAB Components Runtime package
that is automatically downloaded during installation of MicroTrac.
MicroTrac executes on the user's local computer, and no input or output data is transferred on
the internet. Therefore, no personal identifiable information within the input or output files is
transferred from the user's computer.
MicroTrac has some limitations. First, MicroTrac does not run on Apple computers since it was
compiled on a Windows computer. Second, MicroTrac requires specific GPS input data that may
not be available from all types of GPS data loggers. See Section "Running MicroTrac" for input
data requirements. Third, MicroTrac requires GPS samples every 5 seconds. These input data
requirements are needed to match those used during our evaluation of MicroTrac (Breen et al, J
Expo Sci Environ Epidemiol. 2014 24:412-420). Finally, users must provide local dawn and
dusk times for the days with GPS data. Future versions of MicroTrac will address these
limitations.
Installing MicroTrac
MicroTrac must be installed on a 64-bit Windows computer. User needs system administrator
privileges on computer. Computer needs internet connection during installation to download
Matlab runtime software from Mathworks.
To start the installation, download installation file (MicroTrac 1.0 Installation.exe). After
download has completed, double click installation file (MicroTrac 1.0 Installation.exe) and
follow these steps:
1. The 'Destination Location' screen will automatically appear. The default destination
folder is displayed on the screen (C:\Program Files\ MicroTrac 1.0). To change the drive
or location of the folder for the MicroTrac program, press the 'Browse' pushbutton. To
install the program in the default location or user-specified location, press the 'Next'
pushbutton.
2. If this is the first installation of the MicroTrac on the computer, a 'MATLAB Runtime is
required' screen will appear. The installation folder for MATLAB runtime will
automatically appear. The default destination folder is displayed (C:\Program
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Files\MATLAB\MATLAB Runtime). To change the drive or location of the folder for
the program, press the 'Change' pushbutton. Press the 'Next' pushbutton to continue.
3. The "License agreement" screen will appear. Click "Yes" and press the "Next"
pushbutton to continue.
4. The "Confirmation" screen will display the destination folders for the MicroTrac and
MATLAB runtime, also the download size (around 470MB) for the installation. Press
the "Install" pushbutton to begin the installation process.
5. The 'Downloading' screen will automatically appear displaying progress as the files for
the installation are downloading.
6. Wait while a progress bar is displaying. This may take more than several minutes (less
than 30 minutes) to finish.
7. Then a final window "installation completed successfully" confirming successful
installation will appear. Press the 'Finish' pushbutton to close the window.
After installation is complete, the following icon will be placed on desktop.
icroTrai
Running MicroTrac
1. To start MicroTrac, double click on MicroTrac desktop icon. After start-up, MicroTrac
displays the main graphical user interface (GUI) shown in Figure 1. Note: program start-
up time may be a few minutes for first run after installation, and much shorter for
subsequent runs.
2
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@ MicroTrac_vl
-Load input files '
GPS file
Dawn dusk file
Home outline file School outline file Work outline file
Loaded input files -
GPS file
Dawn dusk file
Home outline file
School outline file
Work outline file
Save outputs as
0
Run
r Outputs
Figure 1. MicroTrac GUI
2. To load input files, click push buttons in "Load Input Files" panel of GUI. There are three
types of input files: (1) GPS text file (.csv format) that contains location, speed, and GPS
signal quality data; (2) dawn and dusk file (.csv format) that includes astronomical dawn
and dusk time for each day with GPS data; (3) building outline files (.kml format) for
home, school, and work. All loaded input files should be displayed under the "Loaded
input files" panel of GUI.
Note: A minimum of one building outline file must be loaded to run MicroTrac. If no
outline files are loaded before pushing the "Run" button, the following error message will
be displayed:
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A Error Dialog
en
0
-tZ-
please loa
d at least
OK
ine building outline file
For the GPS file, MicroTrac requires GPS data samples every 5 sec, and uses the file
format created by the GPS data logger used in our studies (model: BT-Q1000XT,
manufacturer: QStarz International, Taiwan). To create a GPS file, copy the column
headers from the example GPS data file: "test gps data.csv". The input data used by
MicroTrac includes: column 5 - local data, column 6 - local time, column 9 - latitude,
column 11 - longitude, column 14 - speed (km/h), column 18 - position dilution of
precision (PDOP); column 21 - number of satellites used (NSAT). The other columns of
data are not used by MicroTrac, but "dummy" values must be included for MicroTrac to
correctly read the GPS file.
For the dawn and dusk file, MicroTrac uses the following file format: column 1: month
(MM), column 2: day (DD), column 3: year (YYYY), column 4: astronomical dawn
(HHMM), column 5: astronomical dusk (HHMM). See example file:
("dawn_dusk_times.csv").
To create building outline files using Google Earth:
1) Open Google Earth
2) In the Search field, enter the address of the building
3) Zoom in until the building outline is visible
4) From the 'Add' pull-down menu, select 'Path'
5) Enter building filename but do not click 'OK' yet
6) Outline building with cursor and left-click at the corners of building
7) When building outline is complete, click 'OK'
8) Go to the 'File' pull-down menu and select 'Save', then scroll over and select 'Save
Place As'. Make sure saved filename is correct, and choose .kml file type.
3. To run MicroTrac, click on "Run" button in GUI. A wait bar will appear ("please wait
MicroTrac is running"). When MicroTrac is done, wait bar will close and MicroTrac
results will be displayed in "Outputs" panel of GUI (Figure 2), which shows percentage
of time spent in each microenvironment.
4. To save MicroTrac results, click on "Save outputs as" and specify filename and location
of output file. Note: a default output file is automatically saved in the folder where
MicroTrac is installed, and named: "MicroTrac_results_mm-dd-yyyy.txt".
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,4- MicroTrac_vl
rLoad input files
S \^3m\
GPS file
Dawn dusk file
Home outline file School outline file Work outline file
Loaded input Tiles
GPS file
Dawn dusk file
Home outline file
School outline file
Work outline file
test_gps_data.csv
dawn dusk times.csv
test home.kml
test school.kml
test work.kml
Save outputs as
Run
-Outputs
HOMEJN = 61.14 Percentage
HOME_OUT = 0.01 Percentage
SCHOOLJN = 0.8B Percentage
SCHOOL_OUT = 0.53 Percentage
WORK_IN = 31.79 Percentage
WORK_OUT = 0.49 Percentage
OTHER = 0.00 Percentage
IN_VEHICLE = 5.17 Percentage
Figure 2. Example MicroTrac outputs in GUI
MicroTrac Results
MicroTrac output file (Figure 3) includes: (1) chronological list of microenvironments entered
with corresponding date and time of day when entering, (2) duration (number of samples) and
percentage of time spent in each microenvironment.
HOMEJN 2010/11/02 09:02:26
INVEHICLE 2010/11/02 09:08:39
SCHOOLOUT 2010/11/02 09:18:04
SCHOOLIN 2010/11/02 09:19:24
SCHOOLOUT 2010/11/02 09:20:52
INVEHICLE 2010/11/02 09:21:36
WORK OUT 2010/11/02 09:34:31
WORKIN 2010/11/02 09:38:38
WORK OUT 2010/11/02 10:17:38
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WORKJN 2010/11/02 10:17:43
WORK OUT 2010/11/02 10:20:58
WORKJN 2010/11/02 10:21:08
IN_VEHICLE 2010/11/02 17:15:23
SCHOOLOUT 2010/11/02 17:32:38
SCHOOL IN 2010/11/02 17:33:08
SCHOOL OUT 2010/11/02 17:44:18
IN_VEHICLE 2010/11/02 17:49:09
HOMEIN 2010/11/02 18:00:09
HOMEOUT 2010/11/03 08:34:54
IN_VEHICLE 2010/11/03 08:34:59
WORK OUT 2010/11/03 08:58:59
WORKJN 2010/11/03 09:01:38
WORKJN 2010/11/03 09:02:28
HOMEJN = 10573 Samples
HOMEOUT = 1 Samples
SCHOOLJN = 152 Samples
SCHOOLOUT = 91 Samples
WORKJN = 5497 Samples
WORK OUT = 85 Samples
OTHER = 0 Samples
INVEHICLE = 894 Samples
HOMEJN = 61.14 Percentage
HOMEOUT = 0.01 Percentage
SCHOOLJN = 0.88 Percentage
SCHOOL OUT = 0.53 Percentage
WORKJN = 31.79 Percentage
WORK OUT = 0.49 Percentage
OTHER = 0.00 Percentage
IN VEHICLE = 5.17 Percentage
Figure 3. Example MicroTrac output file
MicroTrac Example Run
To test MicroTrac, user should run MicroTrac with example input files ("test gps data.csv",
"dawn_duskjime.csv", "test_home.kml", "test_school.kml", "test_work.kml"). Then,
MicroTrac results can be compared with example MicroTrac output file ("test_results.txt"), as
shown in Figure 3.
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