geopython
Add Support for OGC API - Styles
The OGC API - Styles Draft Standard enables map servers, clients as well as visual style editors, to manage and fetch styles. The styles consist of symbolizing instructions that can be applied by a rendering engine on features and/or coverages. The API implements the conceptual model for style encodings and style metadata.
As discussed, an initial iteration could be listing/access of styles via /styles. Future iterations would include association of a style to a resource and transaction interfaces.
I have a question regarding how styles should be configured in the pygeoapi configuration YAML file. Specifically, how should styles be associated with a collection?
For example, should the style be configured under the providers section of a collection, and how would this work for both Mapbox and SLD 1.1 styles? Could you provide a sample configuration for both vector tiles (Mapbox style) and GeoJSON (SLD 1.1)?
Here are two example configurations I'm trying to achieve:
resources:
bathingwater-estonia:
type: collection
title: Bathing water sources
description: Data of bathing water sources used by water supply systems under the supervision of the Health Board from the Water Health Information System.
keywords:
- Water
- Water bodies
- Drilled wells
- Surface water
- Groundwater
- Environmental health
- Health
- Bathing water
links:
- type: text/html
rel: canonical
title: information
href: https://avaandmed.eesti.ee/api/datasets/slug/supluskohad
hreflang: en-US
extents:
spatial:
bbox:
[
22.2290936066586440,
57.6912449743385451,
28.2024877654160555,
59.6097269178904412,
]
crs: http://www.opengis.net/def/crs/OGC/1.3/CRS84
temporal:
begin: null
end: null # or empty
providers:
- type: feature
name: GeoJSON
data: tests/data/tartu/bathingwater-estonia.geojson
id_field: id
styles:
- name: water-bodies
title: Water Bodies SLD Style
style:
type: sld
version: 1.1
data: tests/styles/bathing_water_sources.sld
- type: tile
name: MVT-tippecanoe
data: tests/data/tiles_es/ # local directory tree
options:
zoom:
min: 0
max: 16
format:
name: pbf
mimetype: application/vnd.mapbox-vector-tile
styles:
- name: mapbox style test
title: style title
style:
type: mapbox
data: tests/styles/bathing_water_sources.json
Could you confirm if this is the right way to configure the styles, and if there's anything else that should be included for proper style support?
Additionally, I'm curious about the compatibility of certain style types with specific providers (assuming that it will be under providers). From what I understand, it's possible to define a GeoJSON source (either inline or as a remote URL) within a Mapbox style JSON, but it's not possible to define an SLD style for a vector tiles (PBF) provider. Could you clarify if this assumption is correct?
If there are limitations on which style types (e.g., Mapbox vs. SLD) can be applied to specific providers (e.g., GeoJSON vs. PBF), it would be helpful to understand how pygeoapi handles this, and whether these limitations are enforced in the configuration.
Should we add XML support in https://github.com/geopython/pygeoapi/blob/master/pygeoapi/api/init.py#L81-L101 for SLD ?
Or it will be a different query parameter like ?f=mbsor ?f=sld for example ?
I have a question regarding how styles should be configured in the pygeoapi configuration YAML file. Specifically, how should styles be associated with a collection?
For example, should the style be configured under the providers section of a collection, and how would this work for both Mapbox and SLD 1.1 styles? Could you provide a sample configuration for both vector tiles (Mapbox style) and GeoJSON (SLD 1.1)?
Here are two example configurations I'm trying to achieve:
resources: bathingwater-estonia: type: collection title: Bathing water sources description: Data of bathing water sources used by water supply systems under the supervision of the Health Board from the Water Health Information System. keywords: - Water - Water bodies - Drilled wells - Surface water - Groundwater - Environmental health - Health - Bathing water links: - type: text/html rel: canonical title: information href: https://avaandmed.eesti.ee/api/datasets/slug/supluskohad hreflang: en-US extents: spatial: bbox: [ 22.2290936066586440, 57.6912449743385451, 28.2024877654160555, 59.6097269178904412, ] crs: http://www.opengis.net/def/crs/OGC/1.3/CRS84 temporal: begin: null end: null # or empty providers: - type: feature name: GeoJSON data: tests/data/tartu/bathingwater-estonia.geojson id_field: id styles: - name: water-bodies title: Water Bodies SLD Style style: type: sld version: 1.1 data: tests/styles/bathing_water_sources.sld - type: tile name: MVT-tippecanoe data: tests/data/tiles_es/ # local directory tree options: zoom: min: 0 max: 16 format: name: pbf mimetype: application/vnd.mapbox-vector-tile styles: - name: mapbox style test title: style title style: type: mapbox data: tests/styles/bathing_water_sources.jsonCould you confirm if this is the right way to configure the styles, and if there's anything else that should be included for proper style support?
Additionally, I'm curious about the compatibility of certain style types with specific providers (assuming that it will be under providers). From what I understand, it's possible to define a GeoJSON source (either inline or as a remote URL) within a Mapbox style JSON, but it's not possible to define an SLD style for a vector tiles (PBF) provider. Could you clarify if this assumption is correct?
If there are limitations on which style types (e.g., Mapbox vs. SLD) can be applied to specific providers (e.g., GeoJSON vs. PBF), it would be helpful to understand how pygeoapi handles this, and whether these limitations are enforced in the configuration.
Hi @Youssef-Harby these are all valid questions, but they regard the application of styles in other Standards (e.g: tiles) and we may be stepping ourselves ahead a bit, as we do not have any support for serving the actual style, yet (:
The PR I am working on aims for support for publishing styles, starting from a very simple case (e.g.: SLDs on a folder). Once we are able to provide a list of styles and styles metadata, we can start thinking about calling these styles from other APIs (:
If you have some sample style files that you can provide, as examples, I would be very grateful! ☺️
Thanks, @doublebyte1 . I am using the exercise data from https://dive.pygeoapi.io/setup/ (bathingwater-estonia) to generate a very simple style using QGIS for SLD 1.1 and Maputnik for Mapbox GL style.
tests/styles/bathing_water_sources.json:
{
"version": 8,
"name": "Empty Style",
"metadata": {"maputnik:renderer": "mlgljs"},
"sources": {
"earth": {
"type": "raster",
"tiles": ["https://tile.openstreetmap.org/{z}/{x}/{y}.png"],
"minzoom": 0,
"maxzoom": 16
},
"pygeoapi": {
"type": "vector",
"tiles": [
"https://localhost/collections/bathingwater-estonia/tiles/WebMercatorQuad/{z}/{x}/{y}?f=pbf"
],
"minzoom": 0,
"maxzoom": 16
}
},
"sprite": "",
"glyphs": "https://orangemug.github.io/font-glyphs/glyphs/{fontstack}/{range}.pbf",
"layers": [
{"id": "earth", "type": "raster", "source": "earth"},
{
"id": "bathingwaterestonia",
"type": "circle",
"source": "pygeoapi",
"source-layer": "bathingwaterestonia",
"paint": {"circle-color": "rgba(255, 0, 0, 1)", "circle-radius": 10}
}
],
"id": "oi0gcaa"
}
tests/styles/bathing_water_sources.sld:
<?xml version="1.0" encoding="UTF-8"?>
<StyledLayerDescriptor xmlns="http://www.opengis.net/sld" version="1.1.0" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:ogc="http://www.opengis.net/ogc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:se="http://www.opengis.net/se" xsi:schemaLocation="http://www.opengis.net/sld http://schemas.opengis.net/sld/1.1.0/StyledLayerDescriptor.xsd">
<NamedLayer>
<se:Name>bathingwater-estonia</se:Name>
<UserStyle>
<se:Name>bathingwater-estonia</se:Name>
<se:FeatureTypeStyle>
<se:Rule>
<se:Name>Single symbol</se:Name>
<se:PointSymbolizer>
<se:Graphic>
<se:Mark>
<se:WellKnownName>star</se:WellKnownName>
<se:Fill>
<se:SvgParameter name="fill">#b80808</se:SvgParameter>
</se:Fill>
<se:Stroke>
<se:SvgParameter name="stroke">#b80808</se:SvgParameter>
<se:SvgParameter name="stroke-width">1</se:SvgParameter>
</se:Stroke>
</se:Mark>
<se:Size>24</se:Size>
</se:Graphic>
</se:PointSymbolizer>
<se:PointSymbolizer>
<se:Graphic>
<se:Mark>
<se:WellKnownName>star</se:WellKnownName>
<se:Fill>
<se:SvgParameter name="fill">#ff0000</se:SvgParameter>
</se:Fill>
<se:Stroke>
<se:SvgParameter name="stroke">#ff0000</se:SvgParameter>
<se:SvgParameter name="stroke-width">1</se:SvgParameter>
</se:Stroke>
</se:Mark>
<se:Size>26</se:Size>
<se:Rotation>
<ogc:Literal>34</ogc:Literal>
</se:Rotation>
</se:Graphic>
</se:PointSymbolizer>
</se:Rule>
</se:FeatureTypeStyle>
</UserStyle>
</NamedLayer>
</StyledLayerDescriptor>
Also, I have started working on https://github.com/Youssef-Harby/pygeoapi/tree/styles , incorporating your changes/boilerplate, and began drafting from that point. However, since your plan involves serving only simple SLDs from a directory, I would like to ask if you could provide an example configuration YAML showing how you would prefer the SLD to be defined, so we're aligned on the same page.
@Youssef-Harby: sure, based on your example, I was thinking of something like this (but open to feedback!): 😁
bathingwater-estonia:
type: collection
title: Bathing water sources
description: Data of bathing water sources used by water supply systems under the supervision of the Health Board from the Water Health Information System.
keywords:
- Water
- Water bodies
- Drilled wells
- Surface water
- Groundwater
- Environmental health
- Health
- Bathing water
links:
- type: text/html
rel: canonical
title: information
href: https://avaandmed.eesti.ee/api/datasets/slug/supluskohad
hreflang: en-US
extents:
spatial:
bbox:
[
22.2290936066586440,
57.6912449743385451,
28.2024877654160555,
59.6097269178904412,
]
crs: http://www.opengis.net/def/crs/OGC/1.3/CRS84
temporal:
begin: null
end: null # or empty
providers:
- type: feature
name: GeoJSON
data: tests/data/tartu/bathingwater-estonia.geojson
id_field: id
- type: tile
name: MVT-tippecanoe
data: tests/data/tiles_es/ # local directory tree
options:
zoom:
min: 0
max: 16
format:
name: pbf
mimetype: application/vnd.mapbox-vector-tile
- type: style
name: style-file
options:
format: mbs
data: tests/styles/bathing_water_sources.json # local directory tree
In summary, the type would be the new type, style and we would have to implement one provider to load the style from a file on disk. Ultimately, this plugin should have as option the style format, but for now, we could even remove the options and just assume a default format (e.g.: mapbox or sld).
Catching up here, as @doublebyte1 mentions, we have styles in a couple of contexts. Below are thoughts on workflows:
- OGC API - Styles support: this means listing/fetching styles from a repository (default would be filesystem). We implement this workflow in a similar manner as processes, i.e.:
resources:
my-styles:
type: style
provider: pygeoapi.style.filesystem.MyStyleFileSystemProvider
- Any OGC API that can use a style: this means applying a style definition to generation of a map, tile, etc. In this case, pointing to a style file is fine/safe. A
stylesarray can be used (we can update/normalize in future work w/ maps) to idenitfy 1..n styles in scope. For large workflows/configurations, YAML anchoring/referencing can be leveraged for reuse.
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