5 posts tagged with "anpr"

📌 Key Takeaways (TL;DR)

• Problem: Single-frame OCR inevitably suffers from transient misreadings (e.g., 64아1511, 24가1511) due to vehicle yaw, glare, and vibration.
• Solution: Implemented Korean plate regex validation (^\d{2,3}[가-힣]\d{4}$) coupled with a temporal sliding window majority voting engine across a 7-frame buffer (plate_confirm_threshold=3).
• Result: Advanced through 11 system iterations (v01 to v11), transitioning from initial gibberish (ACCIIXOY-1Z01...) on June 5 to deterministic confirmation of 64가1511 on June 7 with 99.4% reliability.

📌 Key Takeaways (TL;DR)

• Problem: Cropped license plates from dashcam footage often measure under 40x20 pixels with heavy H.264 macroblocking; standard bicubic interpolation fails to resolve character contours.
• Solution: Integrated EDSR_x4 deep residual networks (EDSR_x4.pb) that omit batch normalization to preserve dynamic range, combined with temporal multi-frame image stacking across 3 to 5 consecutive frames.
• Result: Quadrupled plate pixel density and sharpened stroke edges, lifting downstream EasyOCR accuracy on Korean characters from 32% to over 91%.

📌 Key Takeaways (TL;DR)

• Problem: Searching for tiny plates (30x15 pixels) across the raw 640x480 frame generates massive false positives from roadside signs and drops inference speed below 10 FPS.
• Solution: Designed a two-stage hierarchical architecture: broad vehicle detection (YOLOv3-tiny) crops the vehicle ROI, within which a fine-tuned YOLOv5 (lp_det.pt, conf=0.6) locates the license plate. Integrated OpenCV CSRT correlation filter tracking with a 15-frame redetection interval.
• Result: Eliminated 98% of background false positives and slashed GPU overhead by 80%, sustaining real-time 50+ FPS continuous tracking.

📌 Key Takeaways (TL;DR)

• Problem: Dashcam footage contains heavy pavement specular reflection, tar cracks, and road shadows that induce false lane lines; simple coordinate checking cannot reliably catch the exact moment of lane encroachment.
• Solution: Implemented vanishing-point trapezoidal ROI masking, slope thresholding (|slope| > 0.5), and a 7-frame temporal moving average queue. Formulated intrusion as geometric IoU between vehicle tire footprints and lane boundaries.
• Result: Filtered out >95% of road texture noise while capturing vehicle lane crossing events with sub-frame accuracy.

📌 Key Takeaways (TL;DR)

• Problem: Low-resolution dashcam footage suffers from severe vehicle vibration, nighttime backlighting, and heavy motion blur, making direct license plate recognition and lane violation tracking extremely error-prone.
• Solution: Designed a unified 6-stage vision architecture: Canny/Hough lane extraction -> YOLOv3 vehicle detection -> polygon IoU lane violation calculation -> YOLOv5 plate localization -> EDSR_x4 super-resolution -> EasyOCR temporal voting.
• Result: Constructed an end-to-end Python pipeline achieving robust vehicle tracking and lane boundary monitoring even under degraded dashcam conditions.