Case Study


We conducted a study in which we asked 30 participants to take a leisure walk in the neighborhood of Wiedikon district of Zurich, Switzerland. We recorded environmental conditions and the corresponding participant's physiological responses to investigate the relationship between environmental conditions and the corresponding participant's physiological responses.

Anything in the urban environment can influence participants' physiological responses. Thus, the dynamically changing environmental conditions were measured simultaneously with the participant's physiological arousal state measures.

Example of two participants during the study:

Fig A participant at a crossing
Fig A participant walking on street

Urban Environment

Dynamic environmental conditions such as noise, temperature, illuminance, field of view, walkable area and traffic speed have the potential to influence an individual’s perception.

Environmental features
Logo Noise (soundscape) sensor: Smart Cities Board
Manufacturer: Libelium Comunicaciones Distribuidas S.L., Zaragoza (Spain)
Measurement range:50-100 dB
Frequency: 0.4 Hz
Accuracy: ± 2.5 dB
Physical meaning: Visit
Logo Dust sensor: Smart Cities Board
Manufacturer Libelium Comunicaciones Distribuidas S.L., Zaragoza (Spain)
Measurement range: 0.5V/(0.1 mg/m3)
Frequency: 0.4 Hz
Accuracy: Operating supply voltage 5±0.5V
Logo Temperature sensor: HOBO U12 Logger
Manufacturer: Onset Computer Corporation, Bourne, MA, USA
Measurement range: -20°C -70°C
Frequency: 1 Hz
Accuracy: ± 0.35°C from 0°C to 50°C
Logo Relative Humidity Sensor: HOBO U12 Logger
Manufacturer: Onset Computer Corporation, Bourne, MA, USA
Measurement range: 5%-95% (non-condensing)
Measurement unit: %
Frequency: 1 Hz
Accuracy: : ± 2.5% typical, ± 3.5% max
Logo Illuminance sensor: HOBO U12 Logger
Manufacturer: Onset Computer Corporation, Bourne, MA, USA
Measurement range: 10-32,200 lux
Frequency: 1 Hz
Physical meaning: Visit
Logo Global Navigation Satellite System (GNSS)/ Global Positioning System (GPS): Ducat 10 uBlox NEO-M8N, TW2410 Antenna
Manufacturer: Tallysman Wireless Inc.
Measurement: WGS84 spherical coordinates
Frequency: 1Hz
Accuracy: Visit
Logo Computed values as per morphology of urban environment a GPS location.
Isovist area
Isovist perimeter
Isovist occlusivity
Isovist compactness


An Isovist is defined as the area that can be seen from a single vantage point. Benedikt (1979) suggested several properties that can be derived from an Isovist polygon for the characterization of spatial situations. In this study, we are using four Isovist properties: area, perimeter, compactness, and occlusivity. Instead of a 360°­Isovist, we calculated directed 180°­Isovists in order to be able to take account of different evaluations in different directions.

Area: Surface area of the isovist polygon.
Perimeter: Length of the perimeter of the isovist polygon.
Compactness: Ratio of area to perimeter (related to an ideal circle).
Occlusivity: Length of occluding edges.

Fig Explanation of Isovist measures by Benedikt, (1979)

Human Perception

Skin conductance responses of participants were measured with an Emapatica E4 wearable device and processed to detect arousal levels as an indicator of perception.

Fig2 Typical skin conductance response explained by Braithwaite et al., (2013)

Wearable Device: Empatica E4

Electro-dermal Activity (EDA) sensor: sympathetic nervous system arousal measurement of skin conductance
Measurement range: 0.10 to 100 µSiemens
Frequency: 4 Hz

Photoplethysmography Sensor (PPG) sensor: Blood Volume Pulse (BVP) measurements for heart rate variability (HRV) calculations
Photodiodes: 2 Units of Photodiodes consisting of 2 Green LEDs and 2 Red LEDs (15.5 mm2 sensitive area)
Sensor output resolution: 0.9 nW/Digit
Frequency: 64 Hz

Infrared Thermopile: skin temperature measurement
Measurement range: -40 to 115 °C for skin temperature
Frequency: 4 Hz
Accuracy: ± 0.2°C within 36-39°C
Resolution: 0.02°C

Description: The Collected sensor data-sets are uploaded to the Empatica server where Empatica filters the data to remove motion-based artifacts. The processed sensor data are downloadable at emapatica

Research Questions


Our designed sensor kit for collecting environmental and physiological data:

Sensor kit: (download)
HOBO U12 Logger: (download)
E4 Empatica Wearable device: (download)


Benedikt, M. L. (1979) To take hold of space: isovists and isovist fields, Environment and Planning B Planning and Design. Pion Ltd, 6(1), pp. 47–65.

Braithwaite, J. J., Watson, D. G., Jones, R., & Rowe, M. (2013). A guide for analysing electrodermal activity (EDA) & skin conductance responses (SCRs) for psychological experiments. Psychophysiology, 49, 1017-1034.

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