Lane path not matching lane polygon length

When I retrieve the arcline_path_3 associated with a given lane, their length don’t seem to match. Am I doing something wrong? Is this expected?

The screenshot below shows a lane polygon (green) and its associated arcline_path_3 using nusc_map.arcline_path_3.get(my_lane) and discretized points (in orange).


Hi. Could you print the entire code to reproduce this example (incl. loading nuScenes) ?

from nuscenes.map_expansion.map_api import NuScenesMap
import nuscenes.map_expansion.arcline_path_utils as path_utils

import numpy as np
import matplotlib.pyplot as plt

nusc_map_bos = NuScenesMap(dataroot= my_data_root, map_name='boston-seaport')

lane_token = '0a4ae01a-16e1-4366-afe9-1f9d2f1c5480'

lane_path = nusc_map_bos.arcline_path_3.get(lane_token, [])

resolution_meters = 0.5
discretized = np.array(path_utils.discretize_lane(lane_path, resolution_meters))
nusc_map_bos.render_layers(['lane'], 1.0, (8,8), lane_token)

ax = plt.gca()
ax.plot(discretized[:,0], discretized[:,1], 's', color='orange')

ax.set_xlim([840, 900])
ax.set_ylim([1385, 1400])

Hi, the lanes of the map and the arcline paths are not meant to be identical. The lanes are general polygon map information that indicates which area is part of a lane. The arcline or centerline paths are a guide where the AV should drive assuming no obstacles.