A free online tool for measuring hedge porosity from a photograph. Drop in side-on photos of a hedgerow, get a defensible structural-condition figure, per-photo confidence, a heatmap, and a PDF report for SFI HRW1/HRW2 evidence, BNG hedgerow condition, hedgelaying tracking, or natural capital baselines.
2 FREE TRIAL SCANS · NO CARD REQUIRED · SIGN UP FREE FOR 20 PHOTOS / MONTH
Each photograph is measured individually - the fraction of the hedge’s side-on silhouette that is sky-visible, with a confidence label reflecting capture quality.
A typical hedge run is 8–15 photographs. Low-confidence frames are filtered out automatically; the result is a defensible mean for the full hedge.
An optional questionnaire captures what the hedge is being measured for - livestock shelter, drift containment, BNG, runoff, air quality, or general health - so the recommendations land on the right use case.
Designed to survive audit: SFI HRW1/HRW2 evidence packs, BNG hedgerow condition assessments, catchment-sensitive farming payments, natural capital baselines.
Stand 5–10 m back, perpendicular to the hedge, with sky behind. Capture one frame every 5–10 m. A 100 m hedge produces 10–20 photos.
Drag the band on the preview to mask grass, dropped flailings, or ditch margins. The algorithm measures only the hedge.
Per-photo porosity, filtered batch average, confidence label, structural heatmap, and a hedgerow-mode PDF. Export as CSV, attach to your evidence pack.
The photograph-based porosity method has been the field standard for measuring linear vegetation structure since Heisler & DeWalle (1988) and Cornelis & Gabriels (2005). The fluid-dynamic principle is geometry-agnostic - what matters is the silhouette’s gap fraction. Hedgerows are shorter, denser at the base, and usually have grass or crop right against the bottom of the hedge rather than open ground. The capture rules adapt: shorter working distance (5–10 m), more aggressive ground masking, and a relaxed sky-position-at-top rule because hedge photographs routinely include bright wildflower foreground that defeats heuristics tuned for shelterbelts.
The agronomic 20–50% optimum applies to hedgerow shelter the same way it applies to shelterbelts. For purpose-specific hedge functions, the target band shifts: BNG Good-condition basal density correlates with 25–40% porosity; runoff-control hedges aim for 15–35% basal; PM2.5 capture and livestock shelter both peak around 30–50%.
Detailed guides cover each function and the methodology adaptations:
TWO FREE TRIAL SCANS · 20 PHOTOS / MONTH FREE WITH AN ACCOUNT · NO CARD
Try the hedgerow analyser nowA hedgerow analyser measures the optical porosity of a hedge - the fraction of the hedge’s side-on silhouette that is sky-visible - from a photograph. Porosity is the structural-condition number that backs SFI HRW1/HRW2 evidence, BNG hedgerow condition assessments, hedgelaying before/after tracking, spray-drift buffer-zone compliance, runoff control under catchment-sensitive farming, and natural capital baselines. ShelterMetrics is a web-based hedgerow analyser: drop in side-on photos and get a per-hedge porosity figure, batch summary, heatmap, and a branded PDF.
Same Cornelis & Gabriels (2005) methodology, but quality heuristics, working distances, recommendations, and report copy are tuned for hedge geometry. Working distance is 5–10 m back rather than 15–30 m. The aerial-photograph rejection rule and the sky-position-at-top rule are both relaxed in hedgerow mode because they false-positive on hedge shots that include bright wildflower foreground. The PDF talks “hedge” and “hedgelaying” instead of “shelterbelt” and “thinning”.
Yes. HRW1 and HRW2 both reward measurable structural improvement. A measured porosity figure plus dated photographs is the kind of quantitative evidence Defra inspectors increasingly expect, replacing subjective “is it gappy” assessments. See the HRW1/HRW2 evidence guide for the workflow.
It supports the structural side of the assessment - basal density and gappiness - which are two of the criteria a competent ecologist scores under the statutory biodiversity metric. A 25–40% porosity figure is associated with Good-condition basal density. See the BNG hedgerow guide.
No. A phone at chest or waist height covers a hedge of any normal height. Drones earn their keep on shelterbelts above ~5 m. If you do have drone imagery (e.g. ground-truthing a LiDAR survey), the analyser handles it directly. See the drone LiDAR ground-truth guide.
Two scans without signup. The Free tier allows 20 photographs per month with a free account. Pro removes the cap at £19/month or £152/year.