Add Ship detection custom script

sentinel-2/sentinel-2.md

@@ -135,6 +135,8 @@ Dedicated to supplying data for [Copernicus services](https://www.esa.int/Our_Ac
  - [Water In Wetlands Index (WIW)](/sentinel-2/wiw_s2_script)
  - [Simple Water Bodies' Mapping - SWBM ](/sentinel-2/simple_water_bodies_mapping-swbm)
  - [MAGO Water Quality Monitoring Tool](/sentinel-2/mago_water_quality_monitoring_tool)
+ - [Ship detection](/sentinel-2/ship_detection) - highlights ships at sea and their wakes
+
 
 #### Urban planning algorithms
  - [Green city](/sentinel-2/green_city)

sentinel-2/ship_detection/README.md

@@ -0,0 +1,61 @@
+---
+title: Ship detection
+parent: Sentinel-2
+grand_parent: Sentinel
+layout: script
+permalink: /sentinel-2/ship_detection/
+nav_exclude: true
+examples:
+- zoom: '14'
+  lat: '35.39643'
+  lng: '13.21956'
+  datasetId: S2L2A
+  fromTime: '2026-06-02T00:00:00.000Z'
+  toTime: '2026-06-02T23:59:59.999Z'
+  platform:
+  - CDSE
+  - EOB
+  evalscripturl: https://custom-scripts.sentinel-hub.com/custom-scripts/sentinel-2/ship_detection/script.js
+---
+
+## General description
+
+This script highlights **ships** on the open sea in Sentinel-2 L2A optical imagery, and is a
+quick-look / spotting tool for the Copernicus Browser. It is especially useful for fishing
+vessels: alongside the hulls it brings out their **wakes** and - when a purse-seine set is in
+progress - the thin curved **net floatline** arc a seiner pays out around a school.
+
+Vessels are picked out with a simple per-pixel test: over open water the near-infrared (B08) and
+short-wave infrared (B11/B12) reflectances are very low, while a hull is comparatively bright in
+those bands, so a pixel is flagged as a likely vessel when
+
+```
+B08 > SHIP_T_NIR  OR  B11 > SHIP_T_SWIR  OR  B12 > SHIP_T_SWIR
+```
+
+A gamma-stretched true-color base (`WATER_MAX`, `GAMMA`) brings out wakes, slicks and the sunglint
+texture in which floatline arcs are visible.
+
+The script has four modes (set `MODE` at the top):
+
+- `MODE = 0` - **Enhanced true color**: wakes, slicks and sunglint texture.
+- `MODE = 1` - **Vessel highlighter** (default): likely hulls flagged red on a dimmed base.
+- `MODE = 2` - **NIR/SWIR false color**: hulls glow, water goes black.
+- `MODE = 3` - **Glint-stretch (mono)**: maximum surface texture for nets and wakes.
+
+**Tuning:** sunglint varies strongly between scenes, so raise `SHIP_T_NIR` / `SHIP_T_SWIR` over
+bright, glinty water and lower them over calm, dark water. Note this is a *per-pixel* script
+(Sentinel Hub evalscripts have no access to neighbouring pixels), so it spots candidates but does
+not measure or filter them by cluster size - that kind of spatial analysis is a downstream step.
+
+## Description of representative images
+
+Fishing vessels (tuna purse seiners) working SE of Lampedusa (Strait of Sicily) during the
+bluefin season; vessels flagged red with `MODE = 1`. Acquired 2026-06-02.
+
+![Ships highlighted in the Strait of Sicily](fig/fig1.png)
+
+## References
+
+- Sentinel-2 bands: [Sentinel-2 L2A documentation](https://docs.sentinel-hub.com/api/latest/data/sentinel-2-l2a/)
+- Custom scripts evalscript reference: [Evalscript V3](https://docs.sentinel-hub.com/api/latest/evalscript/v3/)

sentinel-2/ship_detection/script.js

@@ -0,0 +1,36 @@
+//VERSION=3
+// ============================================================
+// Purse-seiner / wake / net interpreter for Sentinel-2 L2A
+// Paste into Copernicus Browser -> Custom script. Pick a MODE.
+//   0 = Enhanced true color   -> wakes, slicks, sunglint texture
+//   1 = Vessel highlighter     -> hulls flagged red on a dim base
+//   2 = NIR/SWIR false color   -> hulls glow, water goes black
+//   3 = Glint-stretch (mono)   -> max surface texture for nets/wakes
+// Tune WATER_MAX / GAMMA / SHIP_T_* below.
+// Note: per-pixel only (no spatial filtering in-browser). For wake/net
+// edge enhancement and detection, use the offline toolkit (Run-SeinerScan.ps1).
+// ============================================================
+
+const MODE = 1;
+
+const WATER_MAX = 0.06;   // reflectance mapped to white for water bands (raise to see more texture)
+const GAMMA     = 0.6;    // <1 brightens wakes/slicks
+const STRETCH   = 1.0;    // overall gain
+
+const SHIP_T_NIR  = 0.045; // B08 threshold (hull bright in NIR vs dark water)
+const SHIP_T_SWIR = 0.020; // B11/B12 threshold (water ~0 in SWIR)
+
+function setup() {
+  return { input: ["B02","B03","B04","B08","B11","B12","dataMask"], output: { bands: 3 } };
+}
+function s(x){ let v=Math.max(0,Math.min(1,(x/WATER_MAX)*STRETCH)); return Math.pow(v,GAMMA); }
+function isShip(p){ return (p.B08>SHIP_T_NIR)||(p.B11>SHIP_T_SWIR)||(p.B12>SHIP_T_SWIR); }
+
+function evaluatePixel(p){
+  let tc=[s(p.B04),s(p.B03),s(p.B02)];          // S2 order: R=B04 G=B03 B=B02
+  if (MODE===0) return tc;
+  if (MODE===1){ if(isShip(p)) return [1.0,0.1,0.0]; return [tc[0]*0.5,tc[1]*0.5,tc[2]*0.7]; }
+  if (MODE===2) return [Math.min(1,p.B12*12), Math.min(1,p.B08*12), s(p.B03)];
+  if (MODE===3){ let g=s(p.B03); if(isShip(p)) return [1.0,0.7,0.0]; return [g,g,g]; }
+  return tc;
+}