Project Background
The customer needed a single camera to observe smoke changes at an industrial site and output an electrical signal when black-smoke alarm conditions were confirmed. The system had to run locally on an RK3588 industrial computer to reduce dependence on external networks and cloud inference.
Algorithm and System Implementation
The system uses a two-stage path. A three-frame MobileNetV3-Small ONNX model first detects smoke. During daylight, a second-stage color classifier distinguishes black smoke from non-black smoke. The server reads RTSP, HTTP or local video sources through OpenCV and FFmpeg and converts them to browser-previewable MJPEG.
False-Positive Guards and Regression
The current model configuration is smoke_acceptance_model_v2.6. It includes fixed-camera clear-background protection, structure-constrained static-scene gating, pure-black/pure-color/near-binary graphic guards and an overall_dark guard for extremely dark abnormal frames. In v2.0.3, the new rule was checked against 1,760 readable images without hitting real samples, and 70 automated tests passed.
Site Deployment and Output Linkage
In v2.0.0, image and video tests were verified with MCP2221A output linkage. A single black-smoke test image produced 98.53 percent smoke confidence and 99.99 percent color confidence. A video test sampled 74 frames: 74 were classified as smoke and 73 entered black-smoke candidates. GP0 output high during the test and returned low after the hold period. These results apply only to this test material and site configuration.
Video Stream and Camera Integration
During site troubleshooting, the original 4K H.265 main stream reproduced continuous read failures after about 36 seconds. After switching to a 1080p H.264 substream at about 10 FPS, the MJPEG preview output 235 frames in 40 seconds and remained connected. The finding applies to this camera encoding and network condition.
Applicable Scenarios and Boundaries
This pattern fits fixed-camera industrial smoke observation, edge AI warning, LAN console preview and GPIO alarm output projects. The black-smoke result is a project algorithm output and does not replace official environmental monitoring, emission-grade measurement or regulatory evidence. Formal acceptance should cover no-smoke, smoke onset, continuous black smoke, stream loss, reboot, lens occlusion, rain/fog and backlight conditions.