sar_backscatter.json

{
    "id": "sar_backscatter",
    "summary": "Computes backscatter from SAR input",
    "description": "Computes backscatter from SAR input.\n\nNote that backscatter computation may require instrument specific metadata that is tightly coupled to the original SAR products. As a result, this process may only work in combination with loading data from specific collections, not with general data cubes.\n\nThis process uses bilinear interpolation, both for resampling the DEM and the backscatter.",
    "categories": [
        "cubes",
        "sar"
    ],
    "experimental": true,
    "parameters": [
        {
            "name": "data",
            "description": "The source data cube containing SAR input.",
            "schema": {
                "type": "object",
                "subtype": "datacube",
                "dimensions": [
                    {
                        "type": "spatial",
                        "axis": [
                            "x",
                            "y"
                        ]
                    },
                    {
                        "type": "bands"
                    }
                ]
            }
        },
        {
            "name": "coefficient",
            "description": "Select the radiometric correction coefficient. The following options are available:\n\n* `beta0`: radar brightness\n* `sigma0-ellipsoid`: ground area computed with ellipsoid earth model\n* `sigma0-terrain`: ground area computed with terrain earth model\n* `gamma0-ellipsoid`: ground area computed with ellipsoid earth model in sensor line of sight\n* `gamma0-terrain`: ground area computed with terrain earth model in sensor line of sight (default)\n* `null`: non-normalized backscatter",
            "optional": true,
            "default": "gamma0-terrain",
            "schema": [
                {
                    "type": "string",
                    "enum": [
                        "beta0",
                        "sigma0-ellipsoid",
                        "sigma0-terrain",
                        "gamma0-ellipsoid",
                        "gamma0-terrain"
                    ]
                },
                {
                    "title": "Non-normalized backscatter",
                    "type": "null"
                }
            ]
        },
        {
            "name": "elevation_model",
            "description": "The digital elevation model to use. Set to `null` (the default) to allow the back-end to choose, which will improve portability, but reduce reproducibility.",
            "optional": true,
            "default": null,
            "schema": [
                {
                    "type": "string",
                    "subtype": "collection-id"
                },
                {
                    "type": "null"
                }
            ]
        },
        {
            "name": "mask",
            "description": "If set to `true`, a data mask is added to the bands with the name `mask`. It indicates which values are valid (1), invalid (0) or contain no-data (null).",
            "optional": true,
            "default": false,
            "schema": {
                "type": "boolean"
            }
        },
        {
            "name": "contributing_area",
            "description": "If set to `true`, a DEM-based local contributing area band named `contributing_area` is added. The values are given in square meters.",
            "optional": true,
            "default": false,
            "schema": {
                "type": "boolean"
            }
        },
        {
            "name": "local_incidence_angle",
            "description": "If set to `true`, a DEM-based local incidence angle band named `local_incidence_angle` is added. The values are given in degrees.",
            "optional": true,
            "default": false,
            "schema": {
                "type": "boolean"
            }
        },
        {
            "name": "ellipsoid_incidence_angle",
            "description": "If set to `true`, an ellipsoidal incidence angle band named `ellipsoid_incidence_angle` is added. The values are given in degrees.",
            "optional": true,
            "default": false,
            "schema": {
                "type": "boolean"
            }
        },
        {
            "name": "noise_removal",
            "description": "If set to `false`, no noise removal is applied. Defaults to `true`, which removes noise.",
            "optional": true,
            "default": true,
            "schema": {
                "type": "boolean"
            }
        },
        {
            "description": "Proprietary options for the backscatter computations. Specifying proprietary options will reduce portability.",
            "name": "options",
            "optional": true,
            "default": {},
            "schema": {
                "type": "object",
                "additionalProperties": false
            }
        }
    ],
    "returns": {
        "description": "Backscatter values corresponding to the chosen parametrization. The values are given in linear scale.",
        "schema": {
            "type": "object",
            "subtype": "datacube",
            "dimensions": [
                {
                    "type": "spatial",
                    "axis": [
                        "x",
                        "y"
                    ]
                },
                {
                    "type": "bands"
                }
            ]
        }
    },
    "exceptions": {
        "DigitalElevationModelInvalid": {
            "message": "The digital elevation model specified is either not a DEM or can't be used with the data cube given."
        }
    },
    "links": [
        {
            "rel": "about",
            "href": "https://bok.eo4geo.eu/PP2-2-4-3",
            "title": "Gamma nought (0) explained by EO4GEO body of knowledge."
        },
        {
            "rel": "about",
            "href": "https://bok.eo4geo.eu/PP2-2-4-2",
            "title": "Sigma nought (0) explained by EO4GEO body of knowledge."
        },
        {
            "rel": "about",
            "href": "https://www.geo.uzh.ch/microsite/rsl-documents/research/publications/peer-reviewed-articles/201108-TGRS-Small-tcGamma-3809999360/201108-TGRS-Small-tcGamma.pdf",
            "title": "Flattening Gamma: Radiometric Terrain Correction for SAR Imagery"
        },
        {
            "rel": "about",
            "href": "https://doi.org/10.3390/data4030093",
            "title": "Reasoning behind the choice of bilinear resampling"
        }
    ]
}