Merge pull request #114 from carbonplan/katamartin/crs-reading

Read `crs` information from metadata
carbonplan · Mar 26, 2024 · e94393c · e94393c
2 parents 9fa3ee3 + 6842eb7
commit e94393c
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Showing 3 changed files with 38 additions and 9 deletions.
diff --git a/src/initialize-store.js b/src/initialize-store.js
@@ -10,7 +10,7 @@ const initializeStore = async (source, version, variable, coordinateKeys) => {
   let chunks
   let fill_value
   let dtype
-  let levels, maxZoom, tileSize
+  let levels, maxZoom, tileSize, crs
   const coordinates = {}
   switch (version) {
     case 'v2':
@@ -21,7 +21,7 @@ const initializeStore = async (source, version, variable, coordinateKeys) => {
           resolve()
         })
       )
-      ;({ levels, maxZoom, tileSize } = getPyramidMetadata(
+      ;({ levels, maxZoom, tileSize, crs } = getPyramidMetadata(
         metadata.metadata['.zattrs'].multiscales
       ))
 
@@ -48,7 +48,7 @@ const initializeStore = async (source, version, variable, coordinateKeys) => {
       break
     case 'v3':
       metadata = await fetch(`${source}/zarr.json`).then((res) => res.json())
-      ;({ levels, maxZoom, tileSize } = getPyramidMetadata(
+      ;({ levels, maxZoom, tileSize, crs } = getPyramidMetadata(
         metadata.attributes.multiscales
       ))
 
@@ -114,6 +114,7 @@ const initializeStore = async (source, version, variable, coordinateKeys) => {
     levels,
     maxZoom,
     tileSize,
+    crs,
   }
 }
 

diff --git a/src/tiles.js b/src/tiles.js
@@ -46,7 +46,7 @@ export const createTiles = (regl, opts) => {
     setMetadata,
     order,
     version = 'v2',
-    projection = 'mercator',
+    projection,
   }) {
     this.tiles = {}
     this.loaders = {}
@@ -57,8 +57,6 @@ export const createTiles = (regl, opts) => {
     this.selector = selector
     this.variable = variable
     this.fillValue = fillValue
-    this.projection = projection
-    this.projectionIndex = ['mercator', 'equirectangular'].indexOf(projection)
     this.order = order ?? [1, 1]
     this.invalidate = invalidate
     this.viewport = { viewportHeight: 0, viewportWidth: 0 }
@@ -117,13 +115,31 @@ export const createTiles = (regl, opts) => {
           levels,
           maxZoom,
           tileSize,
+          crs,
         }) => {
           if (setMetadata) setMetadata(metadata)
           this.maxZoom = maxZoom
           this.level = zoomToLevel(this.zoom, maxZoom)
           const position = getPositions(tileSize, mode)
           this.position = regl.buffer(position)
           this.size = tileSize
+          // Respect `projection` prop when provided, otherwise rely on `crs` value from metadata
+          this.projectionIndex = projection
+            ? ['mercator', 'equirectangular'].indexOf(projection)
+            : ['EPSG:3857', 'EPSG:4326'].indexOf(crs)
+          this.projection = ['mercator', 'equirectangular'][
+            this.projectionIndex
+          ]
+
+          if (!this.projection) {
+            this.projection = null
+            throw new Error(
+              projection
+                ? `Unexpected \`projection\` prop provided: '${projection}'. Must be one of 'mercator', 'equirectangular'.`
+                : `Unexpected \`crs\` found in metadata: '${crs}'. Must be one of 'EPSG:3857', 'EPSG:4326'.`
+            )
+          }
+
           if (mode === 'grid' || mode === 'dotgrid') {
             this.count = position.length
           }
@@ -291,6 +307,11 @@ export const createTiles = (regl, opts) => {
     }
 
     this.updateCamera = ({ center, zoom }) => {
+      // Return early if projection not yet initialized
+      if (!this.projection) {
+        return
+      }
+
       const level = zoomToLevel(zoom, this.maxZoom)
       const tile = pointToTile(
         center.lng,

diff --git a/src/utils.js b/src/utils.js
@@ -1,5 +1,4 @@
 import { point, rhumbBearing, rhumbDestination } from '@turf/turf'
-import { select } from 'd3-selection'
 
 const d2r = Math.PI / 180
 
@@ -41,7 +40,7 @@ export const pointToTile = (lon, lat, z, projection, order) => {
       y = Math.max(Math.min(y, z2), 0)
       tile = [x, y, z]
     default:
-      break
+      return
   }
   tile[0] = Math.floor(tile[0])
   tile[1] = Math.min(Math.floor(tile[1]), z2 - 1)
@@ -349,13 +348,21 @@ export const getPyramidMetadata = (multiscales) => {
   const levels = datasets.map((dataset) => Number(dataset.path))
   const maxZoom = Math.max(...levels)
   const tileSize = datasets[0].pixels_per_tile
+  let crs = datasets[0].crs
 
   if (!tileSize) {
     throw new Error(
       'Missing required `pixels_per_tile` value in `multiscales` metadata. Please check your pyramid generation code.'
     )
   }
-  return { levels, maxZoom, tileSize }
+
+  if (!crs) {
+    console.warn(
+      'Missing `crs` value in `multiscales` metadata. Please check your pyramid generation code. Falling back to `crs=EPSG:3857` (Web Mercator)'
+    )
+    crs = 'EPSG:3857'
+  }
+  return { levels, maxZoom, tileSize, crs }
 }
 
 /**