[gdal-dev] Call for discussion on RFC 60: Improved round-tripping in OGR

[Sean Gillies]

Dear all,

This feature is a boost for GeoJSON users who are extending the format and
users of those extensions. JSON is a naturally extensible format but the
GeoJSON OGR driver stifles development of extensions by passing only the
fully standardized GeoJSON items.

Let's say I want to use ogr2ogr to spatially filter some GeoJSON coming
from the OSM Overpass API [1] or the Mapbox Geocoding API [2]. Here's what
the response of the latter looks like, abbreviated:

$ curl
https://api.mapbox.com/v4/geocode/mapbox.places/1600+pennsylvania+ave+nw.json?access_token=$MAPBOX_ACCESS_TOKEN
| python -mjson.tool
{
    "attribution": "NOTICE: \u00a9 2015 Mapbox and its suppliers. All
rights reserved. Use of this data is subject to the Mapbox Terms of Service
(https://www.mapbox.com/about/maps/). This response and the information it
contains may not be retained.",
    "features": [
        {
            "address": "1600",
            "bbox": [
                -77.05781199999998,
                38.89252299999999,
                -77.01844799999999,
                38.905058999999994
            ],
            "center": [
                -77.034389,
                38.897693
            ],
            "context": [
                {
                    "id": "place.57972",
                    "text": "Washington"
                },
                {
                    "id": "postcode.858369517",
                    "text": "20004"
                },
                {
                    "id": "region.1190806886",
                    "text": "District of Columbia"
                },
                {
                    "id": "country.4150104525",
                    "text": "United States"
                }
            ],
            "geometry": {
                "coordinates": [
                    -77.034389,
                    38.897693
                ],
                "type": "Point"
            },
            "id": "address.39053333360279",
            "place_name": "1600 Pennsylvania Ave NW, Washington, 20004,
District of Columbia, United States",
            "properties": {},
            "relevance": 0.99,
            "text": "Pennsylvania Ave NW",
            "type": "Feature"
        },
        ...
    ],
    "query": [
        "1600",
        "pennsylvania",
        "ave",
        "nw"
    ],
    "type": "FeatureCollection"
}

The Features and FeatureCollection have extension items expressing rights,
the original query, and more.

When I pipe this through ogr2ogr to spatially filter, here are the results:

$ curl
https://api.mapbox.com/v4/geocode/mapbox.places/1600+pennsylvania+ave+nw.json?access_token=$MAPBOX_ACCESS_TOKEN
| ogr2ogr -clipsrc -100 30 -70 60 -f GeoJSON /vsistdout/ /vsistdin/
{
"type": "FeatureCollection",
"crs": { "type": "name", "properties": { "name":
"urn:ogc:def:crs:OGC:1.3:CRS84" } },
"features": [
{ "type": "Feature", "properties": { }, "geometry": { "type": "Point",
"coordinates": [ -77.034389, 38.897693 ] } },
{ "type": "Feature", "properties": { }, "geometry": { "type": "Point",
"coordinates": [ -76.634388, 39.30307 ] } },
{ "type": "Feature", "properties": { }, "geometry": { "type": "Point",
"coordinates": [ -80.272062, 40.687045 ] } },
{ "type": "Feature", "properties": { }, "geometry": { "type": "Point",
"coordinates": [ -95.54508, 34.841595 ] } }
]
}

The extensions are lost. This means that ogr2ogr can't be used in pipelines
that process extended GeoJSON.

If you want your GeoJSON to pass through OGR in high fidelity, you have to
put everything in the Feature.properties object no matter whether that's
the best place for it or not. In practice, the Feature.properties object
becomes a grey goo of feature attributes, styling properties, and you name
it.

The implementation of RFC 60 would pass through GeoJSON extensions in full
hi-fi. OGR will no longer be an impediment to extension developers.

[1] http://wiki.openstreetmap.org/wiki/Overpass_turbo/GeoJSON
[2] https://github.com/mapbox/carmen/blob/master/carmen-geojson.md

Yours,


On Wed, Sep 23, 2015 at 9:29 AM, Even Rouault <even.rouault at spatialys.com>
wrote:

> Hi,
>
> This is a call for discussion on "RFC 60: Improved round-tripping in OGR".
>
> https://trac.osgeo.org/gdal/wiki/rfc60_improved_roundtripping_in_ogr
>
> This RFC defines how to improve better round-tripping in conversion of
> vector
> formats, in particular for GeoJSON extensions.
>
> Best regards,
>
> Even
>
> --
> Spatialys - Geospatial professional services
> http://www.spatialys.com
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/gdal-dev
>



-- 
Sean Gillies
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