Glossary
Common terms in the event-camera field (per our implementation). For principles see Fundamentals, and for data formats see Data Formats.
| Term / Abbreviation | Full name / English | Explanation |
|---|---|---|
| EVS | Event-based Vision Sensor | Event camera / event-vision sensor. Each pixel independently and asynchronously reports brightness changes. |
| APS | Active Pixel Sensor | Conventional frame-based image sensor that synchronously captures a full frame at a fixed frame rate. Our cameras fuse EVS + APS (HVS). |
| HVS | Hybrid Vision Sensor | Hybrid vision sensor that fuses RGB (APS) and event (EVS) outputs at the hardware level. |
| CD event | Change Detection event | Change-detection event — the most common "brightness change exceeds threshold" event, containing (x, y, t, p). |
| Polarity | Polarity | The direction of an event: brighten → ON (p=1), darken → OFF (p=0). |
| Timestamp | Timestamp | The instant the event occurred, in microseconds (μs). Type uint64_t. |
| EPS | Events Per Second | Event rate — the number of events generated per second, measuring how dynamically busy the scene is. |
| accumulation time | Accumulation Time | Accumulation time: the time window over which events are accumulated into one frame. Too short → sparse; too long → smear. See Fundamentals. |
| bias | Bias | Configurable pixel parameters of the event camera (sensitivity / threshold / refractory, etc.) that decide the trigger condition. See Bias & Tuning. |
| ROI | Region of Interest | Region of interest — emit events for only some pixels, reducing bandwidth and compute. |
| Denoise | Denoising | Decide whether an event is a real signal or background noise, and discard the noise. We provide 7 algorithms — see Algo. |
| Optical Flow | Optical Flow | The per-pixel motion direction and speed between adjacent event frames. |
| EVT2 | EVT2 format | Standard event-stream format, compatible with Metavision. See Data Formats. |
| RAW8 | RAW8 | MIPI raw packet, the on-board recording format; must be converted to EVT2 before the host software / algorithm library can read it. |
| HVEventsFormat | HV Events Format | Our 64-bit compact event encoding (43-bit timestamp + 10/10-bit coordinates + 1-bit polarity). |
| EVS Network Server | — | The TCP event-stream push service for USB cameras, default port 8888. See EVS Server. |
| EVS Time Sync | — | UDP-based multi-device time synchronization, default port 9999, microsecond-level. See Time Sync. |
| Heartbeat | Heartbeat | In Time Sync, the time-reporting message each device sends to the server once per second. |
| Offset | Offset | In Time Sync, the time deviation (microseconds) of a device relative to the reference device, used to calibrate timestamps. |
| Reference Device | Reference Device | In Time Sync, the first device to connect, which serves as the baseline for other devices' time calibration. |
Easily-confused concepts
Temporal resolution ≠ latency
- Temporal resolution (Timestamp Resolution): the precision of the event timestamp (microsecond-level), determined by the pixel circuit — describes "how finely it is recorded".
- Latency: the end-to-end lag from when an event is generated to when it is actually used downstream (algorithm, actuator), affected by transmission, processing, scheduling, etc.
The two are independent: an event camera can have microsecond temporal resolution while still having millisecond end-to-end latency (depending on the downstream processing chain). Conflating the two overstates the system's real-time performance.