Adds render cross reference in links

This PR Adds render cross reference in links and fix #2
stac-extensions · Apr 17, 2024 · edaeaed · edaeaed
1 parent 9b57094
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -8,6 +8,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- Adds render cross reference in links ([#2](https://github.com/stac-extensions/render/issues/2))
+
 ### Changed
 
 ### Deprecated

diff --git a/README.md b/README.md
@@ -218,6 +218,22 @@ It is highly suggested to have a web map link in the `links` section of the STAC
 [Web Map Link extension](https://github.com/stac-extensions/web-map-links) to allow application to
 find the tiling endpoint of the dynamic tile server.
 
+### Additional Attributes
+
+A [web map link](https://github.com/stac-extensions/web-map-links) can be extended with the attribute `render`
+with a value corresponding to the key of the render object in the `renders` field
+in order to provide a cross link to the render object.
+
+```json
+{
+  "rel": "xyz",
+  "type": "image/png",
+  "title": "NDVI",
+  "href": "https://api.cogeo.xyz/stac/preview.png?url=https://raw.githubusercontent.com/stac-extensions/raster/main/examples/item-landsat8.json&expression=(B5–B4)/(B5+B4)&max_size=512&width=512&resampling_method=average&rescale=-1,1&color_map=ylgn&return_mask=true",
+  "render": "ndvi"
+}
+```
+
 ## Contributing
 
 All contributions are subject to the

diff --git a/examples/item-landsat8.json b/examples/item-landsat8.json
@@ -6,7 +6,8 @@
     "https://stac-extensions.github.io/projection/v1.0.0/schema.json",
     "https://stac-extensions.github.io/view/v1.0.0/schema.json",
     "https://stac-extensions.github.io/render/v1.0.0/schema.json",
-    "https://stac-extensions.github.io/virtual-assets/v1.0.0/schema.json"
+    "https://stac-extensions.github.io/virtual-assets/v1.0.0/schema.json",
+    "https://stac-extensions.github.io/web-map-links/v1.2.0/schema.json"
   ],
   "id": "LC08_L1TP_044033_20210305_20210312_01_T1",
   "properties": {
@@ -66,6 +67,19 @@
       "type": "image/png",
       "title": "RGB composite visualized through a XYZ"
     },
+    {
+      "rel": "xyz",
+      "type": "image/png",
+      "title": "NDVI",
+      "href": "https://api.cogeo.xyz/stac/preview.png?url=https://raw.githubusercontent.com/stac-extensions/raster/main/examples/item-landsat8.json&expression=(B5–B4)/(B5+B4)&max_size=512&width=512&resampling_method=average&rescale=-1,1&color_map=ylgn&return_mask=true",
+      "render": "ndvi"
+    },
+    {
+      "rel": "xyz",
+      "type": "image/png",
+      "title": "NDVI",
+      "href": "https://api.cogeo.xyz/stac/preview.png?url=https://raw.githubusercontent.com/stac-extensions/raster/main/examples/item-landsat8.json&expression=(B5–B4)/(B5+B4)&max_size=512&width=512&resampling_method=average&rescale=-1,1&color_map=ylgn&return_mask=true"
+    },
     {
       "rel": "collection",
       "href": "https://landsat-stac.s3.amazonaws.com/collections/landsat-8-l1.json",

diff --git a/json-schema/schema.json b/json-schema/schema.json
@@ -29,6 +29,37 @@
               }
             }
           }
+        },
+        {
+          "if": {
+            "properties": {
+              "stac_extensions": {
+                "contains": {
+                  "type": "string",
+                  "pattern": "https:\/\/stac-extensions\\.github\\.io\/web-map-links\/.*"
+                }
+              }
+            }
+          },
+          "then": {
+            "properties": {
+              "links": {
+                "type": "array",
+                "contains": {
+                  "type": "object",
+                  "required": [
+                    "rel",
+                    "render"
+                  ],
+                  "properties": {
+                    "render": {
+                      "type": "string"
+                    }
+                  }
+                }
+              }
+            }
+          }
         }
       ]
     },
@@ -55,8 +86,18 @@
         {
           "$comment": "This validates the fields in Collection Assets, but does not require them.",
           "anyOf": [
-            {"type": "object", "required": ["assets"]},
-            {"type": "object", "required": ["item_assets"]}
+            {
+              "type": "object",
+              "required": [
+                "assets"
+              ]
+            },
+            {
+              "type": "object",
+              "required": [
+                "item_assets"
+              ]
+            }
           ],
           "properties": {
             "renders": {
@@ -99,17 +140,72 @@
     "require_any_field": {
       "$comment": "Please list all fields here so that we can force the existence of one of them in other parts of the schemas.",
       "anyOf": [
-        {"type": "object", "required": ["assets"]},
-        {"type": "object", "required": ["title"]},
-        {"type": "object", "required": ["rescale"]},
-        {"type": "object", "required": ["nodata"]},
-        {"type": "object", "required": ["colormap_name"]},
-        {"type": "object", "required": ["colormap"]},
-        {"type": "object", "required": ["color_formula"]},
-        {"type": "object", "required": ["resampling"]},
-        {"type": "object", "required": ["expression"]},
-        {"type": "object", "required": ["minmax_zoom"]},
-        {"type": "object", "required": ["bidx"]}
+        {
+          "type": "object",
+          "required": [
+            "assets"
+          ]
+        },
+        {
+          "type": "object",
+          "required": [
+            "title"
+          ]
+        },
+        {
+          "type": "object",
+          "required": [
+            "rescale"
+          ]
+        },
+        {
+          "type": "object",
+          "required": [
+            "nodata"
+          ]
+        },
+        {
+          "type": "object",
+          "required": [
+            "colormap_name"
+          ]
+        },
+        {
+          "type": "object",
+          "required": [
+            "colormap"
+          ]
+        },
+        {
+          "type": "object",
+          "required": [
+            "color_formula"
+          ]
+        },
+        {
+          "type": "object",
+          "required": [
+            "resampling"
+          ]
+        },
+        {
+          "type": "object",
+          "required": [
+            "expression"
+          ]
+        },
+        {
+          "type": "object",
+          "required": [
+            "minmax_zoom"
+          ]
+        },
+        {
+          "type": "object",
+          "required": [
+            "bidx"
+          ]
+        }
       ]
     },
     "fields": {
@@ -138,7 +234,10 @@
           }
         },
         "nodata": {
-          "type": ["number","string"]
+          "type": [
+            "number",
+            "string"
+          ]
         },
         "colormap_name": {
           "type": "string"
@@ -161,7 +260,7 @@
             "type": "number"
           }
         },
-        "bidx":{
+        "bidx": {
           "type": "array",
           "items": {
             "type": "number"