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Issue #213: Project invalid trajectories inside walkable area #506

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Issue #213: Project invalid trajectories inside walkable area #506

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785c7ec
added preprocessing and trajectory_projector
awestphal1 Nov 13, 2025
61be7f9
started editing user guide, added test file
awestphal1 Nov 26, 2025
12111b4
Fixed Float_Precision Problem and added tests
awestphal1 Nov 27, 2025
c5d0f8c
Current update
awestphal1 Dec 2, 2025
9ac8ec5
new distance function
awestphal1 Dec 4, 2025
1d47c0b
errors for false parameters, better structure, method for catching in…
Dec 4, 2025
15d9c87
Added Errors for Exceptions
Dec 4, 2025
62caaa6
Finish documentation
Dec 7, 2025
16c537b
Merge branch 'preproccesing' into main
Dec 7, 2025
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48 changes: 43 additions & 5 deletions notebooks/user_guide.ipynb
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Original file line number Diff line number Diff line change
Expand Up @@ -2,16 +2,18 @@
"cells": [
{
"cell_type": "code",
"execution_count": null,
"metadata": {
"jupyter": {
"outputs_hidden": false
"outputs_hidden": false,
"is_executing": true
},
"tags": [
"remove-input"
]
],
"ExecuteTime": {
"start_time": "2025-12-07T17:59:35.894792Z"
}
},
"outputs": [],
"source": [
"import pathlib\n",
"import warnings\n",
Expand All @@ -21,7 +23,9 @@
"import shapely\n",
"\n",
"warnings.filterwarnings(\"ignore\")"
]
],
"outputs": [],
"execution_count": null
},
{
"cell_type": "markdown",
Expand Down Expand Up @@ -891,6 +895,40 @@
"get_invalid_trajectory(traj_data=traj, walkable_area=walkable_area_faulty)"
]
},
{
"metadata": {},
"cell_type": "markdown",
"source": [
"## Preprocessing\n",
"\n",
"\n",
"### Trajectory Projector\n",
"\n",
"When working with head trajectories, participants may occasionally lean over obstacles. As a result, their trajectories can leave the walkable area for some frames, and these data cannot be processed by PedPy.\n",
"\n",
"To address this, there is a function that moves trajectory points that lie inside a wall or too close to it. The distance that should remain between the point and the wall afterward is calculated by linear interpolation. The new distance lies within the interval between start_distance and end_distance:\n",
"\n",
"$$\n",
"d' = (d-b)*{(e-s) \\over (e-b)}+s\n",
"$$\n",
"\n",
"- d' is the new distance to the wall\n",
"- d is the original distance to the wall\n",
"- b corresponds to back_distance\n",
"- s corresponds to start_distance\n",
"- e corresponds to end_distance\n",
"\n",
"If a point lies inside the geometry or too close to it, it will be pushed outward. The distance interval for these points starts at back_distance, which must be negative because it represents the maximum depth inside the wall, and ends at end_distance. Points located deeper inside an obstacle are assigned a smaller new distance than points located near the boundary of the interval.\n",
"\n",
"For example, a point lying deep inside an obstacle will receive a new distance close to start_distance, which represents the minimum possible value for new_distance. A point that is already outside the obstacle but needs to be adjusted for smoother results will also receive a new distance, but this value will be only slightly larger than its original distance.\n",
"\n",
"It is essential that end_distance is larger than start_distance, and that back_distance is negative. Depending on the geometry and the parameter values, it can also be beneficial to buffer the geometry beforehand to create thicker walls. If the walls are too thin, the function may accidentally move the point to the wrong side.\n",
"\n",
"The function returns a pedpy.TrajectoryData, either the corrected version of the trajectory or the\n",
" original trajectory, if the original trajectory was valid.\n",
"\n"
]
},
{
"cell_type": "markdown",
"metadata": {},
Expand Down
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