---
license: other
pretty_name: ts-polyline
tags:
  - robotics
  - navigation
  - terrasentia
  - polyline
---

# ts-polyline

TerraSentia (wheeled robot) navigation trajectories from ROS bags,
packaged in a schema mirroring `adipotnis/scand-polyline`. Each row is
one image frame paired with a 60-waypoint future trajectory (next 15 m
of EKF odom sampled at 0.25 m steps), projected into the ZED camera
as a pixel-space polyline and rendered as an overlay PNG.

## Summary

- Total samples: **108491**
- Bags: **22**
- Frames flagged `collision`: **57156** (52.7%)
- Frames flagged `reversing`: **28860** (26.6%)
- Distinct collision events across all bags: **6057**

## Schema

| Field | Type | Notes |
|---|---|---|
| `traj_id` | string | bag stem |
| `robot` | string | constant `"Wheeled Robot"` |
| `run_id` | int32 | per-bag index |
| `sub_id` | int32 | `0` (schema parity with scand-polyline) |
| `n_frames` | int32 | total frames in this bag |
| `frame_idx` | int32 | per-bag frame index |
| `prefix` | string | same as `traj_id` |
| `image` | Image | rectified ZED left frame |
| `image_overlay` | Image | same frame with projected polyline drawn |
| `depth` | Image | nearest ZED registered depth frame, 16-bit PNG in millimeters (0 = invalid). Decode: `np.asarray(row['depth']).astype(np.float32) / 1000.0` to get meters. |
| `traversability` | Image | nearest `/terrasentia/traversability_map` frame, mono8 PNG, 336x188 (lower res than RGB). |
| `embodiments` | List[string] | `["Wheeled Robot"]` |
| `polyline_xy` | List[List[float64,2]] | projected pixel polyline (in-image segment) |
| `traj` | List[List[float64,3]] | up to 60 base-frame waypoints (next 15 m @ 0.25 m) |
| `ground_truth` | dict | `{"Wheeled Robot": [polyline_xy]}` |
| `image_width` / `image_height` | int64 | rectified frame dims |
| `collision` | bool | EKF speed drop in next 5 s (and not reversing) |
| `reversing` | bool | sustained reverse motion in next 5 s |

## Per-bag top-view maps

Forward motion in green, reverse motion in blue, detected collision events as red dots.

### `ts_2023_04_10_20h05m59s_filtered`

- frames: **4334**  ·  collision frames: **3089**  ·  reversing frames: **1682**  ·  collision events: **320**

![ts_2023_04_10_20h05m59s_filtered](topview_maps/ts_2023_04_10_20h05m59s_filtered.png)

### `ts_2023_04_10_20h12m46s_filtered`

- frames: **4508**  ·  collision frames: **2687**  ·  reversing frames: **1960**  ·  collision events: **316**

![ts_2023_04_10_20h12m46s_filtered](topview_maps/ts_2023_04_10_20h12m46s_filtered.png)

### `ts_2023_04_11_17h47m24s_filtered`

- frames: **2276**  ·  collision frames: **1112**  ·  reversing frames: **616**  ·  collision events: **134**

![ts_2023_04_11_17h47m24s_filtered](topview_maps/ts_2023_04_11_17h47m24s_filtered.png)

### `ts_2023_04_11_17h51m03s`

- frames: **6077**  ·  collision frames: **3277**  ·  reversing frames: **1130**  ·  collision events: **298**

![ts_2023_04_11_17h51m03s](topview_maps/ts_2023_04_11_17h51m03s.png)

### `ts_2023_04_11_17h53m56s_filtered`

- frames: **6478**  ·  collision frames: **3325**  ·  reversing frames: **1727**  ·  collision events: **416**

![ts_2023_04_11_17h53m56s_filtered](topview_maps/ts_2023_04_11_17h53m56s_filtered.png)

### `ts_2023_04_11_17h58m32s`

- frames: **9979**  ·  collision frames: **4918**  ·  reversing frames: **1840**  ·  collision events: **493**

![ts_2023_04_11_17h58m32s](topview_maps/ts_2023_04_11_17h58m32s.png)

### `ts_2023_04_11_18h00m20s`

- frames: **7276**  ·  collision frames: **3524**  ·  reversing frames: **1855**  ·  collision events: **338**

![ts_2023_04_11_18h00m20s](topview_maps/ts_2023_04_11_18h00m20s.png)

### `ts_2023_04_11_18h02m48s_filtered`

- frames: **6799**  ·  collision frames: **3194**  ·  reversing frames: **1951**  ·  collision events: **414**

![ts_2023_04_11_18h02m48s_filtered](topview_maps/ts_2023_04_11_18h02m48s_filtered.png)

### `ts_2023_04_11_18h13m59s`

- frames: **2983**  ·  collision frames: **1297**  ·  reversing frames: **537**  ·  collision events: **120**

![ts_2023_04_11_18h13m59s](topview_maps/ts_2023_04_11_18h13m59s.png)

### `ts_2023_04_11_19h57m53s`

- frames: **3693**  ·  collision frames: **1687**  ·  reversing frames: **950**  ·  collision events: **135**

![ts_2023_04_11_19h57m53s](topview_maps/ts_2023_04_11_19h57m53s.png)

### `ts_2023_04_11_20h02m40s`

- frames: **2022**  ·  collision frames: **708**  ·  reversing frames: **484**  ·  collision events: **41**

![ts_2023_04_11_20h02m40s](topview_maps/ts_2023_04_11_20h02m40s.png)

### `ts_2023_06_25_20h32m20s`

- frames: **6417**  ·  collision frames: **3838**  ·  reversing frames: **2181**  ·  collision events: **417**

![ts_2023_06_25_20h32m20s](topview_maps/ts_2023_06_25_20h32m20s.png)

### `ts_2023_06_25_23h24m19s`

- frames: **5280**  ·  collision frames: **2955**  ·  reversing frames: **1463**  ·  collision events: **360**

![ts_2023_06_25_23h24m19s](topview_maps/ts_2023_06_25_23h24m19s.png)

### `ts_2023_06_25_23h34m37s`

- frames: **7269**  ·  collision frames: **3477**  ·  reversing frames: **1706**  ·  collision events: **306**

![ts_2023_06_25_23h34m37s](topview_maps/ts_2023_06_25_23h34m37s.png)

### `ts_2023_06_25_23h56m10s`

- frames: **2050**  ·  collision frames: **1391**  ·  reversing frames: **491**  ·  collision events: **337**

![ts_2023_06_25_23h56m10s](topview_maps/ts_2023_06_25_23h56m10s.png)

### `ts_2023_06_25_23h56m47s`

- frames: **6002**  ·  collision frames: **2645**  ·  reversing frames: **1528**  ·  collision events: **213**

![ts_2023_06_25_23h56m47s](topview_maps/ts_2023_06_25_23h56m47s.png)

### `ts_2023_06_26_00h04m16s`

- frames: **973**  ·  collision frames: **437**  ·  reversing frames: **141**  ·  collision events: **44**

![ts_2023_06_26_00h04m16s](topview_maps/ts_2023_06_26_00h04m16s.png)

### `ts_2023_06_26_00h05m52s`

- frames: **2383**  ·  collision frames: **1319**  ·  reversing frames: **505**  ·  collision events: **153**

![ts_2023_06_26_00h05m52s](topview_maps/ts_2023_06_26_00h05m52s.png)

### `ts_2023_06_26_00h05m58s`

- frames: **4621**  ·  collision frames: **2681**  ·  reversing frames: **1482**  ·  collision events: **245**

![ts_2023_06_26_00h05m58s](topview_maps/ts_2023_06_26_00h05m58s.png)

### `ts_2023_06_26_00h14m59s`

- frames: **1989**  ·  collision frames: **1204**  ·  reversing frames: **564**  ·  collision events: **159**

![ts_2023_06_26_00h14m59s](topview_maps/ts_2023_06_26_00h14m59s.png)

### `ts_2023_06_26_00h15m21s`

- frames: **7259**  ·  collision frames: **3984**  ·  reversing frames: **1992**  ·  collision events: **377**

![ts_2023_06_26_00h15m21s](topview_maps/ts_2023_06_26_00h15m21s.png)

### `ts_2023_06_26_00h25m04s`

- frames: **7823**  ·  collision frames: **4407**  ·  reversing frames: **2075**  ·  collision events: **421**

![ts_2023_06_26_00h25m04s](topview_maps/ts_2023_06_26_00h25m04s.png)

## Detection heuristics

All event detection runs on the EKF stream using `msg.header.stamp` — the rosbag receipt timestamps for `/terrasentia/ekf` are batched in microseconds and don't reflect the true ~100 Hz sample times. The window is the 5 s of EKF following the frame.

**Currently applied (Option B — sharp-decel collision, both flags independent):**

- `reversing`: signed velocity along robot heading is `< -0.05 m/s` for more than 30 % of segments in the window.
- `collision`: speed transitions from `> 0.5 m/s` to `< 0.1 m/s` within `0.3 s` anywhere in the window. The two flags are **not** mutually exclusive — a bump-then-back-up event fires both.

**Alternative considered (Option A — strict, with mutual exclusivity):**

- `reversing`: same as above.
- `collision`: speed transitions from `> 0.5 m/s` to `< 0.05 m/s` within `0.5 s`, **and** stays below `0.05 m/s` for at least `1.0 s`, **and** the frame is not also `reversing`. On TerraSentia teleop this leaves `collision=True` for the rare truly-stuck events; most bumps were labeled `reversing=True` only.

Built with `datasets/ts_data/bags_to_hf_polyline.py`.