This C++ sample has a corresponding Python sample.

Inference Pipeline of Detection and Tracking using C++

This sample allows you to quickly set up an inference pipeline for object detection and tracking. You can use our pre-trained TorchScript model for detection and tracking of vehicles and pedestrians. Check our pre-trained models page to find out how to retrieve the model depending on your Metavision SDK Package.


Note that the network was trained on a dataset recorded by a camera positioned on top of a car facing forward. Its performance might be quite degraded in other settings.

The source code of this sample can be found in <install-prefix>/share/metavision/sdk/ml/cpp_samples/detection_and_tracking_pipeline when installing Metavision SDK from installer or packages. For other deployment methods, check the page Path of Samples.

Expected Output

The pipeline takes events as input and outputs detected objects with bounding boxes and their corresponding confidence level.

The detected and tracked bounding boxes will be shown in two windows set side by side: the detection is shown on the left pane, with colors indicating the class membership; the tracking is drawn on the right with colors indicating the trackID and confidence level.

Setup & requirements

To run the sample, you will need:

  • a pre-trained TorchScript model with a JSON file of hyperparameters. Check our pre-trained models

  • an event-based camera or an event file (RAW, DAT or HDF5). We suggest you to start with driving_sample.raw, downloadable from our Sample Recordings

How to start

First, you need to compile the sample. You should use the compilation guide as a baseline, but the cmake .. step needs to be customized to properly reference libtorch. Here, we assume you followed the Machine Learning Module Dependencies in the installation guide that requires to deploy libtorch in a LIBTORCH_DIR_PATH directory. If so, use those cmake commands to compile:

cmake --build . --config Release

For example, on Windows, if libtorch was installed in C:\libtorch (where you should have, among others, the folders C:\libtorch\cmake and C:\libtorch\lib), then the compilation steps are going to be:

cmake .. -DCMAKE_PREFIX_PATH=C:\libtorch -DTorch_DIR=C:\libtorch -DCMAKE_BUILD_TYPE=Release
cmake --build . --config Release

To start the sample based on recorded data, you need to provide the full path to an event file and the path to the pre-trained model:


metavision_detection_and_tracking_pipeline --record-file <event file to process> --object-detector-dir /path/to/model --display


metavision_detection_and_tracking_pipeline.exe --record-file <event file to process> --object-detector-dir /path/to/model --display

The sample comes with extensive functionalities covering the following aspects:

  • Input: Define the input source, sampling period, start and end timestamp

  • --object_detector_dir: path to a folder containing a model.ptjit torchjit model and a info_ssd_jit.json file containing a few hyperparameters.

  • Output: Produce inference video (.avi), export detected and tracked bbox (in csv format)

  • if --output-video-filename is set, the corresponding file is created.

  • if --output-detections-filename is set, the corresponding file is created. It contains the output boxes of the object detector (the neural network). The format is a csv with one detection box per line, each line containing the following fields (separated by spaces): timestamp, class_id, 0, x, y, width, height, class_confidence

  • if --output-tracks-filename is set, the corresponding file is created. It contains the output boxes of the tracking. The format is a csv with one tracked box per line, each line containing the following fields (separated by commas): timestamp, class_id, track_id, x, y, width, height, class_confidence, tracking_confidence, last_detection_update_time, nb_detections

  • Object Detector: Define the pre-trained detection model and its calibrated hyperparameters; Set up inference thresholds for detection confidence and NMS-IoU level

  • Geometric Preprocessing: Provide geometric preprocessing of event stream: input transposition, filter events outside of a RoI

  • Noise Filtering: Trail and STC filters

  • Data Association: Define matching thresholds for tracking confidence and NMS-IoU level, together with other association parameters

To find the full list of options, run:


metavision_detection_and_tracking_pipeline -h


metavision_detection_and_tracking_pipeline.exe -h