ogr_CityJSON.py

#!/usr/bin/env python
###############################################################################
#
# Purpose:  CityJSON OGR driver
# Author:   Even Rouault <even dot rouault at spatialys.com>
#
###############################################################################
# Copyright (c) 2019, Even Rouault <even dot rouault at spatialys.com>
# SPDX-License-Identifier: MIT
###############################################################################

# Metadata parsed by GDAL C++ code at driver pre-loading, starting with '# gdal: '
# gdal: DRIVER_NAME = "CityJSON"
# gdal: DRIVER_SUPPORTED_API_VERSION = [1]
# gdal: DRIVER_DCAP_VECTOR = "YES"
# gdal: DRIVER_DCAP_VIRTUALIO = "YES"
# gdal: DRIVER_DMD_LONGNAME = "CityJSON"
# gdal: DRIVER_DMD_EXTENSIONS = "json"

import json
import os

from gdal_python_driver import BaseDataset, BaseDriver, BaseLayer


class Layer(BaseLayer):
    def __init__(self, filename, content):
        self.content = content
        self.name = os.path.splitext(os.path.basename(filename))[0]
        self.fields = [
            {"name": "id"},
            {"name": "type"},
        ]

        self.count = 0
        set_attrs = set()
        for key_value in content["CityObjects"].items():
            value = key_value[1]
            if "attributes" in value:
                for kv in value["attributes"].items():
                    if not kv[0] in set_attrs:
                        set_attrs.add(kv[0])
                        v = kv[1]
                        t = "String"
                        if isinstance(v, int):
                            t = "Integer"
                        elif isinstance(v, float):
                            t = "Real"
                        elif "Date" in kv[0]:
                            t = "Date"
                        self.fields.append({"name": kv[0], "type": t})
            for geom in value["geometry"]:
                if geom["type"] in ("Solid", "MultiSurface"):
                    self.count += 1

        md = content["metadata"]
        srs = md["referenceSystem"] if "referenceSystem" in md else None
        if not srs and "crs" in md:
            if isinstance(md["crs"], dict) and "epsg" in md["crs"]:
                srs = "EPSG:" + str(md["crs"]["epsg"])
        self.geometry_fields = [{"type": "MultiPolygonZ", "srs": srs}]
        if "transform" in content:
            self.translate = content["transform"]["translate"]
            self.scale = content["transform"]["scale"]
        else:
            self.translate = [0, 0, 0]
            self.scale = [1, 1, 1]
        self.vertices = content["vertices"]

    def extent(self, force):
        md = self.content["metadata"]
        if "geographicalExtent" in md:
            bbox = md["geographicalExtent"]
        else:
            bbox = md["bbox"]
        return [bbox[0], bbox[1], bbox[3], bbox[4]]

    def feature_count(self, force):
        return self.count

    def __iter__(self):
        fid = 1
        vertices = self.vertices
        scale = self.scale
        translate = self.translate
        for key_value in self.content["CityObjects"].items():
            value = key_value[1]
            for geom in value["geometry"]:
                geom_in = None
                boundaries = geom["boundaries"]
                if geom["type"] == "Solid":
                    assert len(boundaries) == 1, (len(boundaries), key_value)
                    geom_in = boundaries[0]
                elif geom["type"] == "MultiSurface":
                    geom_in = boundaries
                if geom_in:
                    out_mpoly = []
                    for poly in geom_in:
                        out_poly = []
                        for ring in poly:
                            out_ring = []
                            for vertex_idx in ring:
                                v = vertices[vertex_idx]
                                c = [v * s + t for v, s, t in zip(v, scale, translate)]
                                out_ring.append(c)
                            out_ring.append(out_ring[0])
                            out_poly.append(out_ring)
                        out_mpoly.append(out_poly)
                    properties = {"id": key_value[0], "type": value["type"]}
                    if "attributes" in value:
                        properties.update(value["attributes"])

                    wkt = "MULTIPOLYGON Z("
                    first_poly = True
                    for poly in out_mpoly:
                        if not first_poly:
                            wkt += ","
                        else:
                            first_poly = False
                        wkt += "("
                        first_ring = True
                        for ring in poly:
                            if not first_ring:
                                wkt += ","
                            else:
                                first_ring = False
                            wkt += "("
                            first_vertex = True
                            for v in ring:
                                if not first_vertex:
                                    wkt += ","
                                else:
                                    first_vertex = False
                                wkt += "%.18g %.18g %.18g" % (v[0], v[1], v[2])
                            wkt += ")"
                        wkt += ")"
                    wkt += ")"

                    f = {
                        "type": "OGRFeature",
                        "id": fid,
                        "fields": properties,
                        "geometry_fields": {"": wkt},
                    }
                    yield f
                    fid += 1


class Dataset(BaseDataset):
    def __init__(self, filename, content):
        self.layers = [Layer(filename, content)]


class Driver(BaseDriver):
    def identify(self, filename, first_bytes, open_flags, open_options={}):
        return (
            b'"type":"CityJSON"' in first_bytes
            or b'"type": "CityJSON"' in first_bytes
            or first_bytes.startswith(b'{"CityObjects":{')
        )

    def open(self, filename, first_bytes, open_flags, open_options={}):
        if not self.identify(filename, first_bytes, open_flags):
            return None
        if filename.startswith("/vsi"):
            from osgeo import gdal

            f = gdal.VSIFOpenL(filename, "rb")
            if not f:
                return None
            gdal.VSIFSeekL(f, 0, 2)
            length = gdal.VSIFTellL(f)
            gdal.VSIFSeekL(f, 0, 0)
            try:
                content = json.loads(gdal.VSIFReadL(1, length, f))
            finally:
                gdal.VSIFCloseL(f)
        else:
            with open(filename, "rt") as f:
                content = json.loads(f.read())
        return Dataset(filename, content)