Glossary

Technical terms used throughout the PiTrac documentation.

A

ActiveMQ

Legacy message broker previously used for inter-process communication between PiTrac components. Replaced by HTTP POST in current versions.

ADC (Analog-to-Digital Converter)

Circuit that measures an analog voltage and outputs a digital value. Used on the PiTrac connector board to read strobe-LED current during calibration.

APT (Advanced Package Tool)

Command-line package manager on Debian and Raspberry Pi OS (apt install ...). PiTrac's build script installs ~80 system dependencies through APT.

ASGI (Asynchronous Server Gateway Interface)

Python interface standard between async web servers and applications. PiTrac's FastAPI dashboard runs on top of an ASGI server (uvicorn).

Auto-calibration

PiTrac feature that automatically determines focal length and camera angles empirically using a physical calibration rig with golf balls at known positions. Available as a 4-step wizard through the web UI.

B

Ball Speed

One of the three primary measurements provided by PiTrac -- the velocity of the golf ball as measured by the launch monitor system.

BOM (Bill of Materials)

Complete list of every part required to build a PCB or assembly. PiTrac's Parts List serves as the project BOM.

Boost

Large collection of peer-reviewed C++ libraries. PiTrac uses Boost for timers, logging, threading, filesystem access, and regex.

C

Camera Calibration

Process of determining camera angles, focal lengths, and distortion correction matrices needed for PiTrac to accurately locate balls in 3D space.

Calibration Rig

Physical device that positions golf balls at known, fixed distances and angles from PiTrac cameras for the auto-calibration process.

ChArUco Board

Printed calibration pattern that combines a checkerboard with ArUco fiducial markers. PiTrac uses it for distortion correction -- the embedded markers let the detector locate the board even when part of it is occluded or clipped by the frame.

Connector Board

Custom PCB that provides strobe-light switching, camera trigger connections, and power distribution for PiTrac. The current version uses a single +5V input with an integrated boost converter for LED voltage and hardware-enforced duty cycle limiting.

CSI (Camera Serial Interface)

Ribbon-cable interface between a Raspberry Pi and its cameras, built on the MIPI specification. The Pi 5 uses a different connector pitch than older Pi models, so older camera cables need an adapter (FPC).

D

DAC (Digital-to-Analog Converter)

Circuit that converts a digital value into an analog voltage. PiTrac's connector board uses a DAC to set strobe-LED current.

DEB Package

Debian binary package format (.deb). PiTrac distributes pre-built OpenCV and lgpio as DEB packages so installers don't have to compile them.

De-distortion

Process of correcting fish-eye-like lens distortions using matrices calculated during camera calibration. Particularly evident around image edges.

Distortion Matrix

Mathematical matrices used by PiTrac to correct lens distortions in camera images during calibration and operation.

Duty Cycle

Fraction of time a pulsed signal is "on" relative to its total period. PiTrac's strobe LEDs are hardware-limited to a safe maximum duty cycle to prevent overheating.

E

E6/TruGolf

Golf simulator software that PiTrac can interface with. Uses port 2483 for communication.

Extrinsic Calibration

Camera calibration process that determines camera position and orientation in 3D space relative to the scene.

F

FastAPI

Modern asynchronous Python web framework. Powers the PiTrac dashboard and control API.

Flight Camera

Camera 2 in the PiTrac system -- points straight ahead to capture the ball in flight after being hit.

Focal Length

Camera parameter that determines the field of view and magnification. Calculated during camera calibration process.

G

Gerber Files

Standard PCB fabrication format consumed by board houses (JLCPCB, OSH Park, and similar). The PiTrac connector board Gerbers are available in the GitHub repository.

Global Shutter Camera

Type of camera sensor that captures the entire image simultaneously, avoiding rolling shutter artifacts. Required for PiTrac's high-speed ball tracking.

GPIO (General-Purpose Input/Output)

Raspberry Pi pins that can be set high/low or read as digital input. PiTrac drives strobe triggers and talks to the connector-board ADC/DAC over GPIO (via SPI).

GSPro

Golf simulator software that PiTrac can interface with for golf course simulation. Uses port 921 for communication.

H

Hough Transform

OpenCV algorithm used by PiTrac for circle detection in strobed ball images. Can be sensitive and may require tuning for reliable operation. YOLO-based detection is available as an alternative.

HSA (Horizontal Side Angle)

One of the launch angle measurements provided by PiTrac, indicating the ball's horizontal trajectory direction.

I

IMX296

Sony 1.6MP global-shutter CMOS sensor and the standard PiTrac camera sensor. Used in both the Innomaker B0310 module and the Raspberry Pi Global Shutter Camera.

Intrinsic Calibration

Camera calibration process that determines internal camera parameters like focal length and lens distortion characteristics.

IR LED

Infrared light-emitting diode. PiTrac's strobes are high-power IR LEDs that illuminate the ball without being visible to the human eye.

IR-Pass Filter

Optical longpass filter that blocks visible light and transmits infrared (typically >= 700nm). Mounted over the flight camera so only strobe light reaches the sensor, cutting ambient visible-light interference.

J

journalctl

Systemd's log viewer. Use journalctl -u pitrac-web to see web server logs. (The launch monitor itself is not a systemd service -- it runs on demand from the web UI and logs to ~/.pitrac/logs/pitrac.log.)

JSON

JavaScript Object Notation -- lightweight text data format. Used by PiTrac's REST API and generated configuration files such as generated_golf_sim_config.json.

L

Launch Angle

Ball trajectory angle measurements provided by PiTrac, including both vertical and horizontal components.

Launch Monitor

Device category that measures ball-flight parameters (speed, launch angle, spin) for golf simulation and practice. PiTrac is an open-source, DIY launch monitor.

LDO (Low-Dropout Regulator)

Linear voltage regulator that works even when its input voltage is only slightly higher than its output. Used on PiTrac's connector board to supply clean voltage to sensitive components.

lgpio

Modern GPIO library that works with the Raspberry Pi 5's RP1 chip. PiTrac links against lgpio for GPIO access; older libraries (pigpio, wiringPi) don't support the Pi 5.

libcamera

Open-source camera stack and framework used by PiTrac for camera control on Raspberry Pi systems. Commands use rpicam-* on Pi 5.

M

M12 Lens

Miniature threaded lens mount (12mm diameter, 0.5mm pitch) -- the small, inexpensive lens format used by most Pi security cameras. PiTrac typically uses 3.6mm or 6mm M12 lenses.

Meson

C++ build system used to compile PiTrac's pitrac_lm binary (with Ninja as the backend).

MIPI

Mobile Industry Processor Interface. The specification family behind CSI camera and DSI display connectors on the Raspberry Pi and most phones.

MOSFET

Metal-Oxide-Semiconductor Field-Effect Transistor. Fast-switching transistor used on the PiTrac connector board to drive the strobe LEDs.

Motion Blur

Image smearing caused by sensor exposure during object motion. Rolling-shutter cameras also add geometric distortion of moving objects. PiTrac uses global-shutter cameras and short strobes to eliminate both effects.

N

NCNN

Lightweight neural-network inference framework from Tencent. PiTrac uses NCNN to run YOLO ball-detection models directly on the Pi.

Ninja

Small, fast build tool. Meson uses Ninja as its default backend to actually compile PiTrac.

NVMe (Non-Volatile Memory Express)

High-speed SSD storage protocol. Booting the Pi 5 from an NVMe drive (via an NVMe HAT) is substantially faster than booting from an SD card. See Advanced Configuration.

O

OpenCV

Computer vision library used by PiTrac for image processing, including circle detection via Hough transforms and YOLO neural network inference.

Opto-coupler

Component that passes a signal optically rather than electrically, providing galvanic isolation between circuits. Used in the legacy V1 PiTrac connector board; current boards use different isolation.

P

PCB (Printed Circuit Board)

Fiberglass board with etched copper traces that holds electronic components. PiTrac has one custom PCB -- the connector board -- which drives the strobes and routes power.

PID File

Small file holding the process ID of a running service (for example /run/pitrac.pid). PiTrac's services write PID files so management commands can tell whether the launch monitor is already running.

R

REST API

HTTP-based API style where URLs name resources and verbs (GET, POST, PUT, DELETE) act on them. The PiTrac web server exposes a REST API for configuration, shot data, and system status.

Rolling Shutter

Camera-sensor readout mode where rows of pixels are exposed sequentially rather than simultaneously. Causes moving objects to appear sheared or warped and is unusable for high-speed ball tracking. Compare with Global Shutter Camera.

rpicam-apps

Raspberry Pi camera command-line tools (rpicam-hello, rpicam-still, rpicam-vid) that replaced the older libcamera-* utilities on Pi 5.

S

SBC (Single Board Computer)

Complete computer on a single board (CPU, RAM, I/O). The Raspberry Pi 5 is the SBC at the heart of a PiTrac build.

SMD (Surface Mount Device)

Electronic components soldered to pads on the PCB surface rather than inserted through drilled holes. Smaller and harder to hand-solder than through-hole. PiTrac's current connector board mixes SMD and through-hole parts to stay hand-solderable.

SPI (Serial Peripheral Interface)

Synchronous serial protocol that runs over a small set of GPIO pins. PiTrac uses SPI to talk to the strobe DAC on the connector board. Must be enabled in /boot/firmware/config.txt.

Spin Rate

Measurement of golf ball rotation in three axes provided by PiTrac's analysis system.

Stereo Imaging

Using two cameras with known geometry to recover 3D position from pixel disparity. PiTrac uses stereo imaging between Camera 1 (teed ball) and Camera 2 (flight) to derive 3D launch data.

Strobe Light

Infrared LED lighting system that provides short, high-intensity pulses to illuminate the golf ball for high-speed imaging.

Strobed Image

Photograph taken during strobe light pulse showing multiple ball positions for motion analysis.

systemd

Linux service and unit manager. PiTrac's launch-monitor and web-server processes run as systemd services (pitrac, pitrac-web) so they start on boot and can be managed with systemctl.

T

3D Trajectory

The ball's flight path expressed as x/y/z position over time. PiTrac computes a 3D trajectory from the strobed ball images and derives speed, launch angle, and spin from it.

Tee Camera

Camera 1 in the PiTrac system -- angled to watch for the initial ball hit and teed-up ball position.

Through-Hole

Components whose leads pass through drilled holes in the PCB and are soldered on the opposite side. Easier to hand-solder than SMD.

U

uvicorn

Fast ASGI server. Runs PiTrac's FastAPI web dashboard.

V

VSA (Vertical Side Angle)

One of the launch angle measurements provided by PiTrac, indicating the ball's vertical trajectory angle.

W

WebSocket

Bidirectional persistent connection over a single HTTP upgrade. PiTrac's web dashboard uses WebSockets to stream live logs and shot updates from the Pi to the browser without polling.

Y

YAML

Indentation-based human-readable configuration format. PiTrac uses YAML for libcamera pipeline configuration (for example rpi_apps.yaml).

YOLO

Neural network-based ball detection method available as an alternative to the traditional Hough Transform approach. Generally faster and more robust, especially in challenging lighting conditions. Configurable via Configuration > Ball Detection > Detection Method.