- ☀️Daily Log:
- Lit review paper on inferring trip mode and purpose from GPS data
- Source: https://www.sciencedirect.com/science/article/pii/S1877042814041597
- GPS gives richer path data, but needs to be augmented with OD information to be useful
- Machine learning is often utilized to determine the mode, while rule based methods are popular for inferring purpose
- Error detection
- Outliers are identified with unlikely attributes like speed over 250 km/hr
- Successive filters to remove outliers: number of NSAT used to record (<3), HDOP (>5), heading and speed of 0 when GPS data trace is plotted, remove multipath error in urban canyons
- Track points whose distance is less than 10m of the previous one, track points with greater than 200 km/hr speed, track points with less than 5 km/hr and time gap with previous track point of at least 1 minute, delete trips with less than 4 track points
- Trip identification
- The combination of dwell time, speed, and visual checks on map to determine when a set of paths is a trip
- Mode detection
- Input features (from GPS, GIS, Accelerometer, and Respondent’s information)
- duration, speed, acceleration, distance, HDOP/NSAT, heading, street network, rail station, bus routes, bus stops, ownership of vehicle
- Machine learning (NN, Bayesian Network, Decision Tree, SVM)
- Probability Method (Fuzzy logic rules, probability matrix)
- Criteria based Method
- Accuracies of high 70-90% seems to be achievable
- Purpose inference
- Input features (From GIS, GPS, Respondents’ information, other information)
- Land use, POI information, duration of stay, trip ending time, frequent activity, key address, demographic data, transport mode
- Rule based Method (Land-use-and-purpose-matching table, heuristic rules, closest POI matching rules, single deterministic matching method, historical data matching method)
- Probabilistic method (multinomial logit model, probability calculation based on distance)
- Machine learning (classification/regression tree, discriminant analysis)
- Retrospective::
- Daily Stoic::
- Resign over fate is a consistent attitude for stoics
- Trails and triumph from one day doesn’t carry into the next, you can only do your best today