Question on Traffic light face

[adilce009]

Hi there,

May I have some help understanding the following issue?

I have been trying to understand the traffic light features in the dataset. There are two sets of information about it: 'traffic_ligth_face_index_interval' inside frame data and 'tl_faces' arrays. The document refers to the protobuf file for information about traffic_ligth_face_index_interval, but I did not comprehend it quite after reading it.

My question is, given a frame what does the traffic_ligth_face_index_interval refer to (i have observed that in most frames there are 18 indices)? How can I use traffic_llight_face_status of tl_face array to find which traffic light face (red/yellow/green) is active for a lane in a frame?

Thanks