Changes for the UDF data model

I would like to suggest an exchange format that suits all requirements (single file, JSON, easy to serialize, data cube support, vector data support, image collections support), that can be implemented as JSON format or relational table structure.

It supports in a single file:

Data cubes with any number of non-regular dimensions
Image collections
Simple feature collections

Here a simple data cube example:

{
  "type": "TopologicalDataCollection",
  "crs": {
    "EPSG": 4326,
    "WKT": null,
    "temporal": "gregorian"
  },
  "metadata": {
    "name": "Datacollection",
    "description": "New collection",
    "number_of_object_collections": 1,
    "number_of_geometries": 0,
    "number_of_field_collections": 2,
    "number_of_time_stamps": 1,
    "creator": "Soeren",
    "creation_time": "2001-01-01T10:00:00",
    "modification_time": "2001-01-01T10:00:00",
    "source": null,
    "link": null,
    "userdata": null
  },
  "object_collections": {
    "data_cubes": [
      {
        "name": "Data Cube",
        "description": "This is a data cube",
        "dim": ["t", "y", "x"],
        "dimensions": [
          {
            "name": "t",
            "unit": "ISO:8601",
            "size": 3,
            "coordinates": ["2001-01-01T00:00:00", "2001-01-01T00:01:00", "2001-01-01T00:02:00"]
          },
          {
            "name": "x",
            "unit": "degree",
            "size": 3,
            "coordinates": [0, 1, 2]
          },
          {
            "name": "y",
            "unit": "degree",
            "size": 3,
            "coordinates": [0, 1, 2]
          }
        ],
        "field_collection": 0,
        "timestamp": 0
      }
    ],
    "image_collections": [],
    "simple_feature_collections": [],
    "topological_feature_collections": []
  },
  "geometry_collection": [],
  "field_collections": [
    {
      "name": "Climate data",
      "size": [3, 3, 3],
      "number_of_fields": 2,
      "attributes": [
        {
          "name": "Temperature",
          "description": "Temperature",
          "unit": "degree celsius",
          "values": [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0,
            10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0, 18.0,
            19.0, 20.0, 21.0, 22.0, 23.0, 24.0, 25.0, 26.0, 27.0],
          "labels": []
        },
        {
          "name": "Precipitation",
          "description": "Precipitation",
          "unit": "mm",
          "values": [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0,
            10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0, 18.0,
            19.0, 20.0, 21.0, 22.0, 23.0, 24.0, 25.0, 26.0, 27.0],
          "labels": []
        }
      ]
    }
  ],
  "timestamps": [
    [
      "2001-01-01T10:00:00",
      "2001-01-01T00:02:00"
    ]
  ]
}

A simple feature example:

{
  "type": "TopologicalDataCollection",
  "crs": {
    "EPSG": 4326,
    "WKT": null,
    "temporal": "gregorian"
  },
  "metadata": {
    "name": "SimpleFeatureCollection",
    "description": "New collection of 3 simple features that all point to the same field",
    "number_of_object_collections": 1,
    "number_of_geometries": 3,
    "number_of_field_collections": 1,
    "number_of_time_stamps": 1,
    "creator": "Soeren",
    "creation_time": "2001-01-01T10:00:00",
    "modification_time": "2001-01-01T10:00:00",
    "source": null,
    "link": null,
    "userdata": null
  },
  "object_collections": {
    "data_cubes": [],
    "image_collections": [],
    "simple_feature_collections": [
      {
        "name": "Boundary of three lines",
        "description": "Boundary of three lines",
        "number_of_features": 3,
        "bbox": {"min_x": 0.0, "max_x": 3.0, "min_y": 0.0, "max_y": 2.0, "min_z": 0.0, "max_z": 0.0},
        "features": [
          {
            "type": "LineString",
            "predecessors": [],
            "geometry": 0,
            "field": [0, 0],
            "timestamp": 0
          },
          {
            "type": "LineString",
            "predecessors": [],
            "geometry": 1,
            "field": [0, 0],
            "timestamp": 0
          },
          {
            "type": "LineString",
            "predecessors": [],
            "geometry": 2,
            "field": [0, 0],
            "timestamp": 0
          }
        ]
      }
    ],
    "topological_feature_collections": []
  },
  "geometry_collection": [
    "LineString (2 0, 2 2)",
    "LineString (2 2, 0 1, 2 0)",
    "LineString (2 2, 3 1, 2 0)"
  ],
  "field_collections": [
    {
      "name": "Border",
      "size": [1],
      "number_of_fields": 1,
      "attributes": [
        {
          "name": "Landuse",
          "description": "Landuse",
          "unit": "category",
          "values": [],
          "labels": ["Border"]
        }
      ]
    }
  ],
  "timestamps": [["2001-01-01T10:00:00", null]]
}

Attached are the JSON schemas and the Python classes that define the data format:

class CoordinateReferenceSystems(BaseModel):
    """Coordinate reference systems for spatial and temporal coordinates"""
    EPSG: int = Field(None, description="EPSG code", examples=[{"EPSG": 4326}])
    WKT: str = Field(None, description="The WKT description string, if there is no EPSG code")
    temporal: str = Field(None, description="The temporal calender", examples=[{"temporal": "gregorian"}])

class ObjectCollection(BaseModel):
    """Object collection that contains data cubes, image collections,
    simple feature collections and topological feature collections"""
    data_cubes: List[DataCube] = Field(None, description="A list of data cubes")
    image_collections: List[ImageCollection] = Field(None, description="A list of image collections")
    simple_feature_collections: List[SimpleFeatureCollection] = Field(None,
                                                                      description="A list of simple "
                                                                                  "features collections")
    topological_feature_collections: List[TopologicalFeatureCollection] = Field(None,
                                                                                description="A list of topological "
                                                                                            "feature collections")

class TopologicalDataCollection(BaseModel):
    """Topological data collection"""
    type: str = "TopologicalDataCollection"
    crs: CoordinateReferenceSystems = Field(..., description="The coordinate reference systems")
    metadata: Metadata = Field(..., description="The metadata object for the topological data collection")
    object_collections: ObjectCollection = Field(...,
                                                 description="A collection of different "
                                                             "data objects like data cubes, "
                                                             "image collections, simple feature collections "
                                                             "and topological feature collections")
    geometry_collection: List[str] = Field(...,
                                           description="A list of WKT geometry strings that are referenced by the "
                                                       "objects in the object collection.")
    field_collections: List[FieldCollection] = Field(..., description="A list of field collections")
    timestamps: List[Tuple[str, Union[str, None]]] = Field(..., description="A list of timestamp tuples as strings.")

class Metadata(BaseModel):
    """Metadata description of the topological data collection"""

    name: str = Field(...,
                      description="The name of topological data collection. Allowed characters [a-z][A-Z][0-9][_].",
                      examples=[{"name": "Climate_data_collection_1984"}])

    description: str = Field(..., description="Description of the topological data collection.")
    number_of_object_collections: int = Field(..., description="Number of all collections "
                                                               "(data cubes, image collection, "
                                                               "simple feature collections,"
                                                               "topological feature collections).")
    number_of_geometries: int = Field(..., description="Number of all geometries.")
    number_of_field_collections: int = Field(..., description="Number of all field collections.")
    number_of_time_stamps: int = Field(..., description="Number of time tamps.")
    creator: str = Field(None, description="The name of the creator.")
    creation_time: str = Field(None, description="Time of creation.")
    modification_time: str = Field(None, description="Time of last modification.")
    source: str = Field(None, description="The source of the data collections.")
    link: str = Field(None, description="URL link to a specific web source.")
    userdata: dict = Field(None, description="A dictionary of additional metadata (STAC).")

class SimpleFeature(BaseModel):
    """A simple feature definition that may contain (multi)points, (multi)lines or (multi)polygons"""
    type: str = Field(...,
                      description="The type of the simple feature: Point, LineString, "
                                  "Polygon, MultiPoint, MultiLine, MultiPolygon.")
    predecessors: List[int] = Field(None, description="A list of predecessors from which this feature was created.")
    geometry: int = Field(..., description="The index of a geometry from the geometry collection.")
    field: List[int] = Field(None, description="The index of the assigned "
                                               "field collection and the value/label index.")
    timestamp: int = Field(None, description="The index of the assigned timestamp.")

class SimpleFeatureCollection(BaseModel):
    """Simple feature collection: (multi)points, (multi)lines or (multi)polygons"""
    name: str = Field(...,
                      description="The unique name of the simple feature collection."
                                  " Allowed characters [a-z][A-Z][0-9][_].",
                      examples=[{"name": "borders_1984"}])
    description: str = Field(None, description="Description.")
    number_of_features: int = Field(..., description="The number of features.")
    bbox: SpatialBoundingBox = Field(..., description="The bounding box of all features.")
    features: List[SimpleFeature] = Field(..., description="A list of features.")

class SpatialBoundingBox(BaseModel):
    """Spatial bounding box definitions"""

    min_x: float = pyField(..., description="The minimum x coordinate of the 3d bounding box.")
    max_x: float = pyField(..., description="The maximum x coordinate of the 3d bounding box.")

    min_y: float = pyField(..., description="The minimum y coordinate of the 3d bounding box.")
    max_y: float = pyField(..., description="The maximum y coordinate of the 3d bounding box.")

    min_z: float = pyField(..., description="The minimum z coordinate of the 3d bounding box.")
    max_z: float = pyField(..., description="The maximum z coordinate of the 3d bounding box.")

class Dimension(BaseModel):
    """Description of a data cube dimension"""
    name: str = Field(..., description="The name/identifier of the dimension.")
    unit: str = Field(...,
                      description="The unit of the dimension in SI units.",
                      examples=[{"unit": "seconds"}, {"unit": "m"}, {"unit": "hours"},
                                {"unit": "days"}, {"unit": "mm"}, {"unit": "km"}])
    size: int = Field(..., description="The size of the dimension.")
    coordinates: List[Union[int, float, str]] = Field(..., description="A list of coordinates for this dimension")

class DataCube(BaseModel):
    """A multidimensional representation of a data cube"""
    name: str = Field(...,
                      description="The unique name of the data cube. Allowed characters [a-z][A-Z][0-9][_].",
                      examples=[{"name": "Climate_data_cube_1984"}])

    description: str = Field(None, description="Description of the data cube.")
    dim: List[str] = Field(...,
                            description="A an ordered list of dimension names of the data cube. The dimensions "
                                        "are applied in the provided order.",
                            examples=[{"dim": ["t", "y", "x"]}])
    dimensions: List[Dimension] = Field(..., description="A list of dimension descriptions.")
    field_collection: int = Field(None, description="The integer index of the field collection. All fields and their "
                                                    "values of this collection are assigned to the "
                                                    "data cube and must have the same size")
    timestamp: int = Field(None, description="The integer index of the assigned timestamp from the timestamp array")

class Field(BaseModel):
    """This represents a field definition with values and labels"""
    name: str = pyField(...,
                        description="Name of the attribute.")
    description: str = pyField(None, description="Description of the attribute.")
    unit: str = pyField(...,
                        description="The unit of the field.",
                        examples=[{"unit": "m"}, {"unit": "NDVI"}, {"unit": "Watt"}])
    values: List[Union[float, int]] = pyField(...,
                                              description="The field values that must be numeric.",
                                              examples=[{"values": [1, 2, 3]}])
    labels: List[str] = pyField(...,
                                description="Label for each field value.",
                                examples=[{"labels": ["a", "b", "c"]}])

class FieldCollection(BaseModel):
    """A collection of fields that all have the same size"""
    name: str = pyField(..., description="Name of the field collection.")
    size: List[int] = pyField(..., description="The size of the field collection. Each field of "
                                               "this collection must have the same size. The size of "
                                               "the fields can be mutli-dimensional. However, fields are stored "
                                               "as one dimensional array and must be "
                                               "re-shaped in the multi-dimensional form for processing.",
                              examples=[{"size": [100]}, {"size": [3, 3, 3]}])
    number_of_fields: int = pyField(..., description="The number of fields in this collection." )
    attributes: List[Field] = pyField(..., description="A list of fields with the same size.",
                                      alias="fields")

class Image(BaseModel):
    """Description of a raster image. The link to the field collection allows a raster image to have multiple
    values like bands or climate data."""
    name: str = Field(..., description="The name of the image.")
    bbox: SpatialBoundingBox = Field(..., description="The bounding box of this image.")
    number_of_rows: int = Field(..., description="The number of rows of this image.")
    number_of_cols: int = Field(..., description="The number of columns of this image.")
    field_collection: int = Field(..., description="The field collection that is associated to this image. "
                                                   "These field collections must have the same size as this image "
                                                   "and may contain several fields (bands, channels) for this image.")
    timestamp: int = Field(None, description="The index of the assigned timestamp.")

class ImageCollection(BaseModel):
    """An image collection that contains a list of timestamped images that may have multiple bands as data"""
    name: str = Field(...,
                      description="The unique name of the image collection. Allowed characters [a-z][A-Z][0-9][_].",
                      examples=[{"name": "Landsat_image_collection_1984"}])
    description: str = Field(None, description="Description of the image collection.")
    number_of_images: int = Field(..., description="Number of images in this collection.")
    images: List[Image] = Field(..., description="The list of images.")
    timestamp: int = Field(None, description="The index of the assigned timestamp that represents the "
                                             "full temporal extent of the image collection.")

class Polygon(BaseModel):
    """The definition of topological polygons that reference arcs"""
    arcs: List[int] = Field(..., description="The index of the arcs that define the polygon.")
    predecessors: List[int] = Field(None, description="A list of predecessors from which this feature was created.")
    field: List[int] = Field(None, description="The index of the assigned field collection and value.",
                             examples=[{"field": [0, 15]}])
    timestamp: int = Field(None, description="The index of the assigned timestamp.")

class Arc(BaseModel):
    """The definition of a topological arc that is composed of a single LineString"""
    predecessors: List[int] = Field(None, description="The index of predecessors of the same type.")
    geometry: int = Field(..., description="The index of the geometry from the geometry collection.")
    field: List[int] = Field(None, description="The index of the assigned field collection and value.",
                             examples=[{"field": [1, 30]}])
    timestamp: int = Field(None, description="The index of the assigned timestamp.")
    left_polygon: int = Field(None, description="The index of the left side polygon.")
    right_polygon: int = Field(None, description="The index of the right side polygon.")
    shared_arcs_begin: List[Tuple[int, float]] = Field(...,
                                                       description="The indexes and angle tuple of all arcs that are "
                                                                   "shared at the start node in clock wise direction.")
    shared_arcs_end: List[Tuple[int, float]] = Field(...,
                                                     description="The indexes and angle tuple of all arcs that are "
                                                                 "shared at the end node in clock wise direction.")

class TopologicalFeatureCollection(BaseModel):
    """Topological feature collection that may contain arcs and polygons"""
    name: str = Field(...,
                      description="The unique name of the topological feature collection. "
                                  "Allowed characters [a-z][A-Z][0-9][_].",
                      examples=[{"name": "area_and_borders_1984"}])
    description: str = Field(None, description="Description")
    number_of_arcs: int = Field(..., description="The number of arcs.")
    number_of_polygons: int = Field(..., description="The number of polygons.")
    bbox: SpatialBoundingBox = Field(..., description="The bounding box of all features.")
    polygons: List[Polygon] = Field(None, description="A list of topological polygons.")
    arcs: List[Arc] = Field(..., description="A list of topological arcs.")

{
  "title": "TopologicalDataCollection",
  "description": "Topological data collection",
  "type": "object",
  "properties": {
    "type": {
      "title": "Type",
      "default": "TopologicalDataCollection",
      "type": "string"
    },
    "crs": {
      "title": "Crs",
      "description": "The coordinate reference systems",
      "allOf": [
        {
          "$ref": "#/definitions/CoordinateReferenceSystems"
        }
      ]
    },
    "metadata": {
      "title": "Metadata",
      "description": "The metadata object for the topological data collection",
      "allOf": [
        {
          "$ref": "#/definitions/Metadata"
        }
      ]
    },
    "object_collections": {
      "title": "Object Collections",
      "description": "A collection of different data objects like data cubes, image collections, simple feature collections and topological feature collections",
      "allOf": [
        {
          "$ref": "#/definitions/ObjectCollection"
        }
      ]
    },
    "geometry_collection": {
      "title": "Geometry Collection",
      "description": "A list of WKT geometry strings that are referenced by the objects in the object collection.",
      "type": "array",
      "items": {
        "type": "string"
      }
    },
    "field_collections": {
      "title": "Field Collections",
      "description": "A list of field collections",
      "type": "array",
      "items": {
        "$ref": "#/definitions/FieldCollection"
      }
    },
    "timestamps": {
      "title": "Timestamps",
      "description": "A list of timestamp tuples as strings.",
      "type": "array",
      "items": {
        "type": "array",
        "items": [{"type": "string"}, {"type": "string"}]
      }
    }
  },
  "required": ["crs", "metadata", "object_collections", "geometry_collection", "field_collections", "timestamps"],
  "definitions": {
    "CoordinateReferenceSystems": {
      "title": "CoordinateReferenceSystems",
      "description": "Coordinate reference systems for spatial and temporal coordinates",
      "type": "object",
      "properties": {
        "EPSG": {
          "title": "Epsg",
          "description": "EPSG code",
          "examples": [{"EPSG": 4326}],
          "type": "integer"
        },
        "WKT": {
          "title": "Wkt",
          "description": "The WKT description string, if there is no EPSG code",
          "type": "string"
        },
        "temporal": {
          "title": "Temporal",
          "description": "The temporal calender",
          "examples": [{"temporal": "gregorian"}],
          "type": "string"
        }
      }
    },
    "Metadata": {
      "title": "Metadata",
      "description": "Metadata description of the topological data collection",
      "type": "object",
      "properties": {
        "name": {
          "title": "Name",
          "description": "The name of topological data collection. Allowed characters [a-z][A-Z][0-9][_].",
          "examples": [{"name": "Climate_data_collection_1984"}],
          "type": "string"
        },
        "description": {
          "title": "Description",
          "description": "Description of the topological data collection.",
          "type": "string"
        },
        "number_of_object_collections": {
          "title": "Number Of Object Collections",
          "description": "Number of all collections (data cubes, image collection, simple feature collections,topological feature collections).",
          "type": "integer"
        },
        "number_of_geometries": {
          "title": "Number Of Geometries",
          "description": "Number of all geometries.",
          "type": "integer"
        },
        "number_of_field_collections": {
          "title": "Number Of Field Collections",
          "description": "Number of all field collections.",
          "type": "integer"
        },
        "number_of_time_stamps": {
          "title": "Number Of Time Stamps",
          "description": "Number of time tamps.",
          "type": "integer"
        },
        "creator": {
          "title": "Creator",
          "description": "The name of the creator.",
          "type": "string"
        },
        "creation_time": {
          "title": "Creation Time",
          "description": "Time of creation.",
          "type": "string"
        },
        "modification_time": {
          "title": "Modification Time",
          "description": "Time of last modification.",
          "type": "string"
        },
        "source": {
          "title": "Source",
          "description": "The source of the data collections.",
          "type": "string"
        },
        "link": {
          "title": "Link",
          "description": "URL link to a specific web source.",
          "type": "string"
        },
        "userdata": {
          "title": "Userdata",
          "description": "A dictionary of additional metadata (STAC).",
          "type": "object"
        }
      },
      "required": ["name", "description", "number_of_object_collections", "number_of_geometries", "number_of_field_collections", "number_of_time_stamps"]
    },
    "Dimension": {
      "title": "Dimension",
      "description": "Description of a data cube dimension",
      "type": "object",
      "properties": {
        "name": {
          "title": "Name",
          "description": "The name/identifier of the dimension.",
          "type": "string"
        },
        "unit": {
          "title": "Unit",
          "description": "The unit of the dimension in SI units.",
          "examples": [{"unit": "seconds"}, {"unit": "m"}, {"unit": "hours"}, {"unit": "days"}, {"unit": "mm"}, {"unit": "km"}],
          "type": "string"
        },
        "size": {
          "title": "Size",
          "description": "The size of the dimension.",
          "type": "integer"
        },
        "coordinates": {
          "title": "Coordinates",
          "description": "A list of coordinates for this dimension",
          "type": "array",
          "items": {
            "anyOf": [{"type": "integer"}, {"type": "number"}, {"type": "string"}]
          }
        }
      },
      "required": ["name", "unit", "size", "coordinates"]
    },
    "DataCube": {
      "title": "DataCube",
      "description": "A multidimensional representation of a data cube",
      "type": "object",
      "properties": {
        "name": {
          "title": "Name",
          "description": "The unique name of the data cube. Allowed characters [a-z][A-Z][0-9][_].",
          "examples": [{"name": "Climate_data_cube_1984"}],
          "type": "string"
        },
        "description": {
          "title": "Description",
          "description": "Description of the data cube.",
          "type": "string"
        },
        "dim": {
          "title": "Dim",
          "description": "A an ordered list of dimension names of the data cube. The dimensions are applied in the provided order.",
          "examples": [{"dim": ["t", "y", "x"]}],
          "type": "array",
          "items": {
            "type": "string"
          }
        },
        "dimensions": {
          "title": "Dimensions",
          "description": "A list of dimension descriptions.",
          "type": "array",
          "items": {
            "$ref": "#/definitions/Dimension"
          }
        },
        "field_collection": {
          "title": "Field Collection",
          "description": "The integer index of the field collection. All fields and their values of this collection are assigned to the data cube and must have the same size",
          "type": "integer"
        },
        "timestamp": {
          "title": "Timestamp",
          "description": "The integer index of the assigned timestamp from the timestamp array",
          "type": "integer"
        }
      },
      "required": ["name", "dim", "dimensions"]
    },
    "SpatialBoundingBox": {
      "title": "SpatialBoundingBox",
      "description": "Spatial bounding box definitions",
      "type": "object",
      "properties": {
        "min_x": {
          "title": "Min X",
          "description": "The minimum x coordinate of the 3d bounding box.",
          "type": "number"
        },
        "max_x": {
          "title": "Max X",
          "description": "The maximum x coordinate of the 3d bounding box.",
          "type": "number"
        },
        "min_y": {
          "title": "Min Y",
          "description": "The minimum y coordinate of the 3d bounding box.",
          "type": "number"
        },
        "max_y": {
          "title": "Max Y",
          "description": "The maximum y coordinate of the 3d bounding box.",
          "type": "number"
        },
        "min_z": {
          "title": "Min Z",
          "description": "The minimum z coordinate of the 3d bounding box.",
          "type": "number"
        },
        "max_z": {
          "title": "Max Z",
          "description": "The maximum z coordinate of the 3d bounding box.",
          "type": "number"
        }
      },
      "required": ["min_x", "max_x", "min_y", "max_y", "min_z", "max_z"]
    },
    "Image": {
      "title": "Image",
      "description": "Description of a raster image. The link to the field collection allows a raster image to have multiple\nvalues like bands or climate data.",
      "type": "object",
      "properties": {
        "name": {
          "title": "Name",
          "description": "The name of the image.",
          "type": "string"
        },
        "bbox": {
          "title": "Bbox",
          "description": "The bounding box of this image.",
          "allOf": [
            {
              "$ref": "#/definitions/SpatialBoundingBox"
            }
          ]
        },
        "number_of_rows": {
          "title": "Number Of Rows",
          "description": "The number of rows of this image.",
          "type": "integer"
        },
        "number_of_cols": {
          "title": "Number Of Cols",
          "description": "The number of columns of this image.",
          "type": "integer"
        },
        "field_collection": {
          "title": "Field Collection",
          "description": "The field collection that is associated to this image. These field collections must have the same size as this image and may contain several fields (bands, channels) for this image.",
          "type": "integer"
        },
        "timestamp": {
          "title": "Timestamp",
          "description": "The index of the assigned timestamp.",
          "type": "integer"
        }
      },
      "required": ["name", "bbox", "number_of_rows", "number_of_cols", "field_collection"]
    },
    "ImageCollection": {
      "title": "ImageCollection",
      "description": "An image collection that contains a list of timestamped images that may have multiple bands as data",
      "type": "object",
      "properties": {
        "name": {
          "title": "Name",
          "description": "The unique name of the image collection. Allowed characters [a-z][A-Z][0-9][_].",
          "examples": [{"name": "Landsat_image_collection_1984"}],
          "type": "string"
        },
        "description": {
          "title": "Description",
          "description": "Description of the image collection.",
          "type": "string"
        },
        "number_of_images": {
          "title": "Number Of Images",
          "description": "Number of images in this collection.",
          "type": "integer"
        },
        "images": {
          "title": "Images",
          "description": "The list of images.",
          "type": "array",
          "items": {
            "$ref": "#/definitions/Image"
          }
        },
        "timestamp": {
          "title": "Timestamp",
          "description": "The index of the assigned timestamp that represents the full temporal extent of the image collection.",
          "type": "integer"
        }
      },
      "required": ["name", "number_of_images", "images"]
    },
    "SimpleFeature": {
      "title": "SimpleFeature",
      "description": "A simple feature definition that may contain (multi)points, (multi)lines or (multi)polygons",
      "type": "object",
      "properties": {
        "type": {
          "title": "Type",
          "description": "The type of the simple feature: Point, LineString, Polygon, MultiPoint, MultiLine, MultiPolygon.",
          "type": "string"
        },
        "predecessors": {
          "title": "Predecessors",
          "description": "A list of predecessors from which this feature was created.",
          "type": "array",
          "items": {
            "type": "integer"
          }
        },
        "geometry": {
          "title": "Geometry",
          "description": "The index of a geometry from the geometry collection.",
          "type": "integer"
        },
        "field": {
          "title": "Field",
          "description": "The index of the assigned field collection and the value/label index.",
          "type": "array",
          "items": {
            "type": "integer"
          }
        },
        "timestamp": {
          "title": "Timestamp",
          "description": "The index of the assigned timestamp.",
          "type": "integer"
        }
      },
      "required": [
        "type",
        "geometry"
      ]
    },
    "SimpleFeatureCollection": {
      "title": "SimpleFeatureCollection",
      "description": "Simple feature collection: (multi)points, (multi)lines or (multi)polygons",
      "type": "object",
      "properties": {
        "name": {
          "title": "Name",
          "description": "The unique name of the simple feature collection. Allowed characters [a-z][A-Z][0-9][_].",
          "examples": [
            {
              "name": "borders_1984"
            }
          ],
          "type": "string"
        },
        "description": {
          "title": "Description",
          "description": "Description.",
          "type": "string"
        },
        "number_of_features": {
          "title": "Number Of Features",
          "description": "The number of features.",
          "type": "integer"
        },
        "bbox": {
          "title": "Bbox",
          "description": "The bounding box of all features.",
          "allOf": [
            {
              "$ref": "#/definitions/SpatialBoundingBox"
            }
          ]
        },
        "features": {
          "title": "Features",
          "description": "A list of features.",
          "type": "array",
          "items": {
            "$ref": "#/definitions/SimpleFeature"
          }
        }
      },
      "required": ["name", "number_of_features", "bbox", "features"]
    },
    "Polygon": {
      "title": "Polygon",
      "description": "The definition of topological polygons that reference arcs",
      "type": "object",
      "properties": {
        "arcs": {
          "title": "Arcs",
          "description": "The index of the arcs that define the polygon.",
          "type": "array",
          "items": {
            "type": "integer"
          }
        },
        "predecessors": {
          "title": "Predecessors",
          "description": "A list of predecessors from which this feature was created.",
          "type": "array",
          "items": {
            "type": "integer"
          }
        },
        "field": {
          "title": "Field",
          "description": "The index of the assigned field collection and value.",
          "examples": [{"field": [0, 15]}],
          "type": "array",
          "items": {
            "type": "integer"
          }
        },
        "timestamp": {
          "title": "Timestamp",
          "description": "The index of the assigned timestamp.",
          "type": "integer"
        }
      },
      "required": [
        "arcs"
      ]
    },
    "Arc": {
      "title": "Arc",
      "description": "The definition of a topological arc that is composed of a single LineString",
      "type": "object",
      "properties": {
        "predecessors": {
          "title": "Predecessors",
          "description": "The index of predecessors of the same type.",
          "type": "array",
          "items": {
            "type": "integer"
          }
        },
        "geometry": {
          "title": "Geometry",
          "description": "The index of the geometry from the geometry collection.",
          "type": "integer"
        },
        "field": {
          "title": "Field",
          "description": "The index of the assigned field collection and value.",
          "examples": [{"field": [1, 30]}],
          "type": "array",
          "items": {
            "type": "integer"
          }
        },
        "timestamp": {
          "title": "Timestamp",
          "description": "The index of the assigned timestamp.",
          "type": "integer"
        },
        "left_polygon": {
          "title": "Left Polygon",
          "description": "The index of the left side polygon.",
          "type": "integer"
        },
        "right_polygon": {
          "title": "Right Polygon",
          "description": "The index of the right side polygon.",
          "type": "integer"
        },
        "shared_arcs_begin": {
          "title": "Shared Arcs Begin",
          "description": "The indexes and angle tuple of all arcs that are shared at the start node in clock wise direction.",
          "type": "array",
          "items": {
            "type": "array",
            "items": [{"type": "integer"}, {"type": "number"}]
          }
        },
        "shared_arcs_end": {
          "title": "Shared Arcs End",
          "description": "The indexes and angle tuple of all arcs that are shared at the end node in clock wise direction.",
          "type": "array",
          "items": {
            "type": "array",
            "items": [{"type": "integer"}, {"type": "number"}]
          }
        }
      },
      "required": [
        "geometry",
        "shared_arcs_begin",
        "shared_arcs_end"
      ]
    },
    "TopologicalFeatureCollection": {
      "title": "TopologicalFeatureCollection",
      "description": "Topological feature collection that may contain arcs and polygons",
      "type": "object",
      "properties": {
        "name": {
          "title": "Name",
          "description": "The unique name of the topological feature collection. Allowed characters [a-z][A-Z][0-9][_].",
          "examples": [
            {
              "name": "area_and_borders_1984"
            }
          ],
          "type": "string"
        },
        "description": {
          "title": "Description",
          "description": "Description",
          "type": "string"
        },
        "number_of_arcs": {
          "title": "Number Of Arcs",
          "description": "The number of arcs.",
          "type": "integer"
        },
        "number_of_polygons": {
          "title": "Number Of Polygons",
          "description": "The number of polygons.",
          "type": "integer"
        },
        "bbox": {
          "title": "Bbox",
          "description": "The bounding box of all features.",
          "allOf": [
            {
              "$ref": "#/definitions/SpatialBoundingBox"
            }
          ]
        },
        "polygons": {
          "title": "Polygons",
          "description": "A list of topological polygons.",
          "type": "array",
          "items": {
            "$ref": "#/definitions/Polygon"
          }
        },
        "arcs": {
          "title": "Arcs",
          "description": "A list of topological arcs.",
          "type": "array",
          "items": {
            "$ref": "#/definitions/Arc"
          }
        }
      },
      "required": ["name", "number_of_arcs", "number_of_polygons", "bbox", "arcs"]
    },
    "ObjectCollection": {
      "title": "ObjectCollection",
      "description": "Object collection that contains data cubes, image collections,\nsimple feature collections and topological feature collections",
      "type": "object",
      "properties": {
        "data_cubes": {
          "title": "Data Cubes",
          "description": "A list of data cubes",
          "type": "array",
          "items": {
            "$ref": "#/definitions/DataCube"
          }
        },
        "image_collections": {
          "title": "Image Collections",
          "description": "A list of image collections",
          "type": "array",
          "items": {
            "$ref": "#/definitions/ImageCollection"
          }
        },
        "simple_feature_collections": {
          "title": "Simple Feature Collections",
          "description": "A list of simple features collections",
          "type": "array",
          "items": {
            "$ref": "#/definitions/SimpleFeatureCollection"
          }
        },
        "topological_feature_collections": {
          "title": "Topological Feature Collections",
          "description": "A list of topological feature collections",
          "type": "array",
          "items": {
            "$ref": "#/definitions/TopologicalFeatureCollection"
          }
        }
      }
    },
    "Field": {
      "title": "Field",
      "description": "This represents a field definition with values and labels",
      "type": "object",
      "properties": {
        "name": {
          "title": "Name",
          "description": "Name of the attribute.",
          "type": "string"
        },
        "description": {
          "title": "Description",
          "description": "Description of the attribute.",
          "type": "string"
        },
        "unit": {
          "title": "Unit",
          "description": "The unit of the field.",
          "examples": [{"unit": "m"}, {"unit": "NDVI"}, {"unit": "Watt"}],
          "type": "string"
        },
        "values": {
          "title": "Values",
          "description": "The field values that must be numeric.",
          "examples": [{"values": [1, 2, 3]}],
          "type": "array",
          "items": {
            "anyOf": [{"type": "number"}, {"type": "integer"}]
          }
        },
        "labels": {
          "title": "Labels",
          "description": "Label for each field value.",
          "examples": [{"labels": ["a", "b", "c"]}],
          "type": "array",
          "items": {
            "type": "string"
          }
        }
      },
      "required": ["name", "unit", "values", "labels"]
    },
    "FieldCollection": {
      "title": "FieldCollection",
      "description": "A collection of fields that all have the same size",
      "type": "object",
      "properties": {
        "name": {
          "title": "Name",
          "description": "Name of the field collection.",
          "type": "string"
        },
        "size": {
          "title": "Size",
          "description": "The size of the field collection. Each field of this collection must have the same size. The size of the fields can be mutli-dimensional. However, fields are stored as one dimensional array and must be re-shaped in the multi-dimensional form for processing.",
          "examples": [{"size": [100]}, {"size": [3, 3, 3]}],
          "type": "array",
          "items": {
            "type": "integer"
          }
        },
        "number_of_fields": {
          "title": "Number Of Fields",
          "description": "The number of fields in this collection.",
          "type": "integer"
        },
        "fields": {
          "title": "Fields",
          "description": "A list of fields with the same size.",
          "type": "array",
          "items": {
            "$ref": "#/definitions/Field"
          }
        }
      },
      "required": ["name", "size", "number_of_fields", "fields"]
    }
  }
}

Open-EO / openeo-udf

Changes for the UDF data model #14