1hew-ComfyUI-1hewNodes/web/docs/1hew_DetectGuideLine/en.md

Detect Guide Line - Vanishing-point guided line detection

Node Purpose: Detect Guide Line detects line segments, estimates the vanishing point via intersection clustering, and draws guide lines from segment endpoints to the vanishing point. Outputs the annotated image, a lines-only image, and a binary mask.

Inputs

Name	Port	Type	Default	Range	Description
image	-	IMAGE	-	-	Input image batch.
canny_low	-	FLOAT	0.2	0.0-1.0	Lower Canny threshold (scaled to 0–255).
canny_high	-	FLOAT	0.8	0.0-1.0	Upper Canny threshold; clamped ≥ canny_low.
seg_min_len	-	INT	40	1-300	Minimum line length for Hough (minLineLength).
seg_max_gap	-	INT	8	1-100	Maximum gap for Hough (maxLineGap).
guide_filter	-	FLOAT	0.6	0.1-1.0	Line selection strength (percentile-based).
guide_width	-	INT	2	1-100	Drawing thickness (pixels).
cluster_eps	-	INT	30	1-100	DBSCAN eps for intersection clustering.

Outputs

Name	Type	Description
image	IMAGE	Annotated image with red guide lines and vanishing point.
line_image	IMAGE	Lines-only image on black, with vanishing point.
line_mask	MASK	Binary mask (B×H×W) of guide lines and vanishing point.

Features

• Edge detection: Canny on blurred grayscale; HoughLinesP to get segments.
• Vanishing point: extend segments, compute pairwise intersections, cluster with DBSCAN to pick the dominant vanishing point.
• Line selection: scores lines by alignment to vanishing point directions; selects by percentile controlled by guide_filter.
• Rendering: draws lines from each endpoint to the vanishing point; adds a red dot at the vanishing point.
• Batch async: per-frame processing offloaded to threads with bounded concurrency.

Typical Usage

• Highlight perspective lines and estimate a vanishing point for composition guidance.
• Increase seg_min_len/decrease seg_max_gap to reduce short/noisy segments.
• Tune cluster_eps according to image scale so intersection clusters converge.

Notes & Tips

• When no lines or intersections are found, outputs are valid tensors with zeros.
• guide_filter affects the percentile: stronger values select fewer, stronger-aligned lines.