Question on maplibre example: Where does the source-layer id come from? #430

michaelkirk · 2024-08-06T19:24:46Z

michaelkirk
Aug 6, 2024

I assumed that source-layer was supposed to correspond to the id of one of the vector_layers in the pmtiles metadata.

But with regards to

PMTiles/js/examples/maplibre.html

Line 53 in 721c65e

"source-layer":"landuse",

...
layers: [                            
    {                            
        "id":"buildings",                            
        "source": "example_source",                            
        "source-layer":"landuse",   // <-- ❓what does this correspond to?
        "type": "fill",                            
        "paint": {                            
            "fill-color": "steelblue"                            
        }                            
    },  
...

From what I can see in the pmtiles metadata, there is no vector layer with id landuse. So then, where is this layer coming from?

pmtiles metadata via

$ pmtiles show protomaps\(vector\)ODbL_firenze.pmtiles --tilejson

{
	"attribution": "\u003ca href=\"https://protomaps.com\" target=\"_blank\"\u003eProtomaps\u003c/a\u003e © \u003ca href=\"https://www.openstreetmap.org\" target=\"_blank\"\u003e OpenStreetMap\u003c/a\u003e",
	"bounds": [
		11.154026,
		43.7270125,
		11.3289395,
		43.8325455
	],
	"center": [
		11.2414827,
		43.779779,
		0
	],
	"maxzoom": 14,
	"minzoom": 0,
	"name": "protomaps 2023-01-18T07:49:39Z",
	"scheme": "xyz",
	"tilejson": "3.0.0",
	"tiles": [
		"https://example.com/{z}/{x}/{y}.mvt"
	],
	"vector_layers": [
		{
			"fields": {},
			"id": "earth"
		},
		{
			"fields": {
				"boundary": "string",
				"landuse": "string",
				"leisure": "string",
				"name": "string",
				"natural": "string"
			},
			"id": "natural"
		},
		{
			"fields": {
				"aeroway": "string",
				"amenity": "string",
				"area:aeroway": "string",
				"highway": "string",
				"landuse": "string",
				"leisure": "string",
				"man_made": "string",
				"name": "string",
				"place": "string",
				"pmap:kind": "string",
				"railway": "string",
				"sport": "string"
			},
			"id": "land"
		},
		{
			"fields": {
				"landuse": "string",
				"leisure": "string",
				"name": "string",
				"natural": "string",
				"water": "string",
				"waterway": "string"
			},
			"id": "water"
		},
		{
			"fields": {
				"natural": "string",
				"waterway": "string"
			},
			"id": "physical_line"
		},
		{
			"fields": {
				"building:part": "string",
				"height": "number",
				"layer": "string",
				"name": "string"
			},
			"id": "buildings"
		},
		{
			"fields": {
				"ele": "number",
				"name": "string",
				"natural": "string",
				"place": "string"
			},
			"id": "physical_point"
		},
		{
			"fields": {
				"capital": "string",
				"country_code_iso3166_1_alpha_2": "string",
				"name": "string",
				"place": "string",
				"pmap:kind": "string",
				"pmap:rank": "string",
				"population": "string"
			},
			"id": "places"
		},
		{
			"fields": {
				"bridge": "string",
				"highway": "string",
				"layer": "string",
				"oneway": "string",
				"pmap:kind": "string",
				"ref": "string",
				"tunnel": "string"
			},
			"id": "roads"
		},
		{
			"fields": {
				"aerialway": "string",
				"aeroway": "string",
				"highspeed": "string",
				"layer": "string",
				"name": "string",
				"network": "string",
				"pmap:kind": "string",
				"railway": "string",
				"ref": "string",
				"route": "string",
				"service": "string"
			},
			"id": "transit"
		},
		{
			"fields": {
				"amenity": "string",
				"cuisine": "string",
				"name": "string",
				"railway": "string",
				"religion": "string",
				"shop": "string",
				"tourism": "string"
			},
			"id": "pois"
		},
		{
			"fields": {
				"pmap:min_admin_level": "number"
			},
			"id": "boundaries"
		},
		{
			"fields": {},
			"id": "mask"
		}
	]
}