Update countries geojson file to use ONS BFE

src/server/plugins/engine/components/helpers/geospatial.ts

@@ -16,7 +16,8 @@ import {
   type FeatureProperties,
   type Geometry
 } from '~/src/server/plugins/engine/types.js'
-import { countries } from '~/src/server/plugins/map/routes/index.js'
+import { countriesValidate } from '~/src/server/plugins/map/routes/index.js'
+import { CountryMap } from '~/src/server/plugins/map/types.js'
 
 const Joi = JoiBase.extend({
   type: 'array',
@@ -157,8 +158,8 @@ export function getGeospatialSchema(
   }
 
   const validateCountryBounds: CustomValidator = (value, helpers) => {
-    const countryFeature = countries.features.find(
-      (feature) => feature.id === country
+    const countryFeature = countriesValidate.features.find(
+      (feature) => feature.id === CountryMap[country]
     )
 
     if (!countryFeature) {
@@ -191,8 +192,8 @@ export function getEastingNorthingCountryValidator(
   country: GeospatialFieldOptionsCountry
 ) {
   const validateCountryBounds: CustomValidator = (value, helpers) => {
-    const countryFeature = countries.features.find(
-      (feature) => feature.id === country
+    const countryFeature = countriesValidate.features.find(
+      (feature) => feature.id === CountryMap[country]
     )
 
     if (!countryFeature) {

src/server/plugins/map/routes/index.js

@@ -7,18 +7,36 @@ import Joi from 'joi'
 
 import { getAccessToken } from '~/src/server/plugins/map/routes/get-os-token.js'
 import { find } from '~/src/server/plugins/map/service.js'
+import { CountryMap } from '~/src/server/plugins/map/types.js'
 import {
   get,
   request as httpRequest
 } from '~/src/server/services/httpService.js'
 
-const filePath = resolve(import.meta.dirname, './vts/countries.geojson')
+const countriesDisplayFilePath = resolve(
+  import.meta.dirname,
+  './vts/countries.geojson'
+)
+const countriesValidateFilePath = resolve(
+  import.meta.dirname,
+  './vts/countries-5dp.geojson'
+)
 
 /**
  * @type {FeatureCollection}
  */
 // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
-export const countries = JSON.parse(fs.readFileSync(filePath, 'utf8'))
+export const countries = JSON.parse(
+  fs.readFileSync(countriesDisplayFilePath, 'utf8')
+)
+
+/**
+ * @type {FeatureCollection}
+ */
+// eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+export const countriesValidate = JSON.parse(
+  fs.readFileSync(countriesValidateFilePath, 'utf8')
+)
 
 export const countrySchema = Joi.string().valid(
   ...Object.values(GeospatialFieldOptionsCountryEnum)
@@ -188,14 +206,18 @@ function getGeospatialCountries() {
       if (omit) {
         return {
           ...countries,
-          features: countries.features.filter((feature) => feature.id !== omit)
+          features: countries.features.filter(
+            (feature) => feature.id !== CountryMap[omit]
+          )
         }
       }
 
       if (only) {
         return {
           ...countries,
-          features: countries.features.filter((feature) => feature.id === only)
+          features: countries.features.filter(
+            (feature) => feature.id === CountryMap[only]
+          )
         }
       }
 

src/server/plugins/map/routes/vts/README.md

@@ -1,5 +1,43 @@
+# VTS
+
 File in this directory are sourced from https://github.com/OrdnanceSurvey/OS-Vector-Tile-API-Stylesheets
 
 VTS_OUTDOOR_URL=https://raw.githubusercontent.com/OrdnanceSurvey/OS-Vector-Tile-API-Stylesheets/main/OS_VTS_3857_Outdoor.json
 VTS_DARK_URL=https://raw.githubusercontent.com/OrdnanceSurvey/OS-Vector-Tile-API-Stylesheets/main/OS_VTS_3857_Dark.json
 VTS_BLACK_AND_WHITE_URL=https://raw.githubusercontent.com/OrdnanceSurvey/OS-Vector-Tile-API-Stylesheets/main/OS_VTS_3857_Black_and_White.json
+
+# Country boundaries
+
+The [Office for National Statistics provides full-resolution boundaries](https://www.ons.gov.uk/methodology/geography/geographicalproducts/digitalboundaries) in two coastal forms.
+We use "BFE" a full resolution — extent of the realm and generally extends to Mean Low Water rather than clipping at Mean High Water.
+
+The latest version of the data is from 2025 and can be found at the following links:
+
+https://geoportal.statistics.gov.uk/datasets/591803c2a3b94804a3d7895cc127d7c0_0/explore?location=50.529309%2C-4.098782%2C7
+
+Download from: http://geoportal.statistics.gov.uk/ or https://geoportal.statistics.gov.uk/datasets/ons::countries-december-2025-boundaries-uk-bfe/about
+
+The source data is for the 2025 revision is 179MB so needs to be reduced to allow rendering in a Web map and used for validation on the server. The downloaded file is named `boundaries-bfe.geojson`. `org2ogr` is used to produce two files:
+
+## Server-side validation (boundaries-bfe-5dp.geojson)
+
+This is the full file but with coordinate precision reduced from 14 to 5 decimal places, resulting in a smaller file of 83.7MB.
+This data is then used server-side to validate points, shapes and lines that include country restrictions.
+
+`ogr2ogr --config OGR_GEOJSON_MAX_OBJ_SIZE 0 -f GeoJSON boundaries-bfe-5dp.geojson boundaries-bfe.geojson -lco COORDINATE_PRECISION=5`
+
+## Client-side display on map (boundaries-bfe-5dp.geojson)
+
+To produce a file suitable for use in the map in the browser we use `ogr2ogr`'s `simplify` option.
+
+`-simplify 0.001` uses the units of the input CRS. In EPSG:4326, that's degrees, not metres so a tolerance of 0.001° is roughly 111 metres north–south, which is quite a substantial simplification for coastal boundaries. For 0.001 to mean approximately one metre, we have to reproject to a suitable projected CRS (BNG, EPSG:27700) before simplifying:
+
+The following command produces `boundaries-bng.geojson`, the source file reprojected to BNG.
+
+`ogr2ogr --config OGR_GEOJSON_MAX_OBJ_SIZE 0 -f GeoJSON boundaries-bng.geojson boundaries-bfe.geojson -t_srs EPSG:27700`
+
+We then use this to create a simplified dataset, `countries.geojson`, reprojected back in ESPG:4326:
+
+`ogr2ogr --config OGR_GEOJSON_MAX_OBJ_SIZE 0 -f GeoJSON countries.geojson boundaries-bng.json -simplify 100 -t_srs EPSG:4326 -lco COORDINATE_PRECISION=5`
+
+The result is a file of 940kB that is suitable to use in the web map.