Polygon_token Values in singapore-queenstown.json (nuScenes Map Expansion v1.3)

[bantouro]

Hi
I am using the official nuScenes map expansion pack (v1.3) downloaded from your website (https://www.nuscenes.org/). When loading the singapore-queenstown.jsonfile with the official nuscenes-devkit, I observed that in the road_block layer, all 676 records have their polygon_tokenfield set to null. However, the current map_api.py assumes that every non-geometric polygon layer has a valid polygon_token. Could you please confirm whether this is expected, or if the singapore-queenstown.json file might be corrupted / outdated on my side?Thank you very much for your help.

[whyekit-motional]

@bantouro pls provide a (working) code snippet to reproduce the issue

[bantouro]

@whyekit-motional Hey, sorry I didn’t include the reproduce code earlier. Here’s what happened: I tried to render only a few road_blocks with the devkit, but whatever token I pass, the road_block overlay looks the same and basically shows the whole Singapore-Queenstown map. I dug into the data and found that in data/sets/nuscenes/maps/expansion/singapore-queenstown.json, every road_block has polygon_token: null, unlike other maps (e.g., boston-seaport.json) where each road_block has a valid polygon_token. The devkit logic is fine; it just needs polygon_token to exist. It seems the Map expansion v1.3 Queenstown JSON is missing those polygons. I couldn’t find another way to reach the nuScenes team, so I’m asking here on GitHub. So I want to confirm whether this is as expected. Below is the reproduced code and result:

from nuscenes.map_expansion.map_api import NuScenesMap
import matplotlib.pyplot as plt

dataroot = r"D:\data\sets\nuscenes"
nusc_map = NuScenesMap(dataroot=dataroot, map_name="singapore-queenstown")

# Check if road_block entries have missing polygon_token.
null_polygon_tokens = [
    rb["token"] for rb in nusc_map.road_block
    if rb.get("polygon_token") is None
]
print(f"road_block total: {len(nusc_map.road_block)}, null polygon_token: {len(null_polygon_tokens)}")
if null_polygon_tokens:
    print("Example road_block token with null polygon_token:", null_polygon_tokens[0])

first_rb = nusc_map.road_block[0]
print("polygon_token of first road_block:", first_rb["polygon_token"]) 
# Try to render only this road_block
fig, ax = nusc_map.render_layers(['road_block'], tokens=[first_rb['token']])
plt.savefig('road_block-singapore-queenstown-0.png', dpi=400, bbox_inches='tight')

second_rb = nusc_map.road_block[1]
print("polygon_token of second road_block:", second_rb["polygon_token"])
# Try to render only this road_block
fig, ax = nusc_map.render_layers(['road_block'], tokens=[second_rb['token']])
plt.savefig('road_block-singapore-queenstown-1.png', dpi=400, bbox_inches='tight')

Output：

road_block total: 676, null polygon_token: 676
Example road_block token with null polygon_token: 002615fa-423c-464b-80e4-8bd3b85e6465
polygon_token of first road_block: None
polygon_token of second road_block: None

road_block-singapore-queenstown-0.png:

road_block-singapore-queenstown-1.png:

If you use nusc_map.render_record('road_block', nusc_map.road_block[0]['token'], other_layers=[]) to render the result:

If I were to draw it using another map, it would look like this. It appears to be a section of road, rather than the entire map: