Timestamp Processing

The C++ backend (rko_lio::core::process_timestamps) tries to automatically decide whether a LiDAR timestamp sequence is absolute (already aligned to wall-clock time) or relative (offsets that must be shifted by the message header time). If the data cannot be confidently classified as either, a std::runtime_error is thrown:

Runtime Error: TimestampProcessingConfig does not cover this particular
case of data. Please investigate, modify the config, or open an issue.

When this error occurs, you can potentially adjust the timestamps section of your configuration file to fix the issue. Typically, specifying one of force_absolute or force_relative should do the trick.

Example (default configuration)

your other configuration keys here
timestamps:
  multiplier_to_seconds: 0.0
  force_absolute: false
  force_relative: false
  absolute_start_threshold: 1
  absolute_end_threshold: 1
  relative_start_threshold: 10
  relative_end_threshold: 10

Description of parameters

• multiplier_to_seconds:

  Factor applied to raw timestamp values to convert them to seconds. Secondsd and nanoseconds are detected automatically when this is 0.0 (default). Specify this for any other case. For example, if timestamps are in microseconds, use 1e-6.

• force_absolute:

  If set, timestamps are always treated as absolute, bypassing heuristics.

• force_relative:

  If set, timestamps are always interpreted as relative to the LiDAR message header time, bypassing heuristics.

• absolute_start_threshold:

  A tolerance around the earliest measured timestamp compared to header time. If its absolute difference to the header time is below this threshold, the scan is treated as absolute.

  Units: milliseconds.

• absolute_end_threshold:

  Similar to the above, but applied to the latest scan timestamp. the absolute difference is compared to this threshold.

  Units: milliseconds.

• relative_start_threshold:

  Used to check for relative timestamps. If the scan’s absolute minimum time is below this threshold, the timestamps are considered relative.

  Units: milliseconds.

• relative_end_threshold:

  Also used for relative checks. If the scan’s absolute maximum time is below this threshold, the timestamps are considered relative. The expectation is the max time is either a very small negative or positive value.

  Units: milliseconds.

Note

First, absolute timestamps are checked for. Then, relative. If the threshold checks are still not satisfied, then the above described error is thrown.