DATA_PIPELINE.md

Alpasim data

This document is meant to describe data handling in Alpasim to help test and data engineers build the test cases they want and troubleshoot issues.

asl files

The output of simulation in alpasim are asl files (it stands for AlpaSim Log). These are a size-delimited protobuf stream with a custom schema defined here. Each rollout will create its own asl file with three types of messages:

• A metadata header (see RolloutMetadata) aiming to help with reproducibility and book keeping
• Actor poses (see ActorPoses) messages which inform about the location of all actors (including 'EGO') in global coordinate space
• Microservice requests and responses (see *_request/*_return messages) which enable reproducing behavior of a given service in replay mode without starting up the entire simulator

📗 RolloutCameraImage requests allow for assembling an .mp4 video out of an .asl log.

⚠️ The simulation header doesn't specify the usdz file uuid.

Reading asl logs

alpasim-grpc provides async_read_pb_log for reading asl logs as a stream of messages. An example usage to print the first 20 messages in a log (since async_read_pb_log is an async function it needs to be executed from a jupyter notebook or submitted to an async runtime loop):

from alpasim_grpc.utils.logs import async_read_pb_log

i = 0
async for log_entry in async_read_pb_log("<path_to_log>.asl"):
    print(log_entry)
    i += 1
    if i == 20:
        break

results in

rollout_metadata {
  session_metadata {
    session_uuid: "a5823758-a782-11ef-aa43-0242c0a89003"
    scene_id: "clipgt-3055a5c9-53e8-4e20-b41a-19c0f917b081"
    batch_size: 1
    n_sim_steps: 120
    start_timestamp_us: 1689697803493732
    control_timestep_us: 99000
  }
  actor_definitions {
  }
  force_gt_duration: 1700000
  version_ids {
    runtime_version {
      version_id: "0.3.0"
      git_hash: "83bf78502c43dabac683d68b3712cdca17f6a810+dirty"
      grpc_api_version {
        minor: 24
      }
    }
    egodriver_version {
      version_id: "0.0.0"
      git_hash: "mock"
      grpc_api_version {
        minor: 23
...
    image_bytes: "\377\330\377\340\000\020JFIF\000\001..."
  }
}

Output is truncated.