f_directional

Note Master 25-07-2026

Does the person's small movement during the stay follow the direction of a street? Someone standing on a street often moves along it. Someone inside a building moves in more random directions.

For a street candidate, the score is high when the movement follows that street:

\[f_\text{directional}(E_k, C_i) = \frac{1}{n-1} \sum_{j=1}^{n-1} |\cos(\theta_j - \theta_{E_k})|\]

For a building or open-space candidate, movement along a nearby street counts against it. The score is 1 minus the best match with any nearby street, so every candidate gets a value:

\[f_\text{directional}(E_k, C_i) = 1 - \max_{s \in \text{Adjacent}(E_k)} \left\{ \frac{1}{n-1} \sum_{j=1}^{n-1} |\cos(\theta_j - \theta_s)| \right\}\]

\(\theta_j\) is the direction from point \(j\) to point \(j+1\). It is only computed for steps longer than 0.5 m, to ignore GPS noise. \(\theta_{E_k}\) is the direction of the street, taken from its shape on the map. \(\text{Adjacent}(E_k)\) means the street pieces within 30 m. If no step is longer than 0.5 m, the score is a neutral 0.5.

In the models: finding the right form took three tests: Directional scope ablation (3a vs 3b), its overlap with the ASC terms in Model 5: alternative-specific constants (rejected), and finally f_directional: shared vs split. The final answer is one weight shared by all three place types.

Part of Framework overview.

Linked from Assignment framework · Directional scope ablation (3a vs 3b) · Framework overview · Model 2: share-type and sigma · Model 5: alternative-specific constants (rejected) · f_directional: shared vs split