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Identify - Image Service (Operation)

This is an archive of a previous version of the ArcGIS REST API. The current version can be found at http://resources.arcgis.com/en/help/arcgis-rest-api/

URL http://<imageservice-url>/identify
Parent Resource Image Service

Description

The identify operation is performed on an image service resource. It identifies the content of an image service for a given location and a given mosaic rule. The location can be a point or a polygon.

The identify operation is supported by all kinds of image services (Mosaic Datasets, Raster Datasets or an Image Service definition).

The result of this operation includes the pixel value of the mosaic for a given mosaic rule, a resolution (pixel size), and a set of catalog items that overlap the given geometry. The single pixel value is that of the mosaic at the centroid of the specified location. If there are multiple rasters overlapping the location, the visibility of a raster is determined by the order of the rasters defined in the mosaic rule. It also contains a set of catalog items that overlap the given geometry. The catalog items are ordered based on the mosaic rule. A list of catalog item visibilities gives the percentage contribution of the item to overall mosaic.

You can provide arguments to the identify operation as query parameters defined in the parameters table below.

Parameters

Parameter Details
f Description: The response format. The default response format is html.

Values: html | json
geometry Required
Description: A geometry that defines the location to be identified. The location can be a point or a polygon. The structure of the geometry is the same as the structure of the json geometry objects returned by the ArcGIS REST API. In addition to the JSON structures, for points, you can specify the geometry with a simpler comma-separated syntax.

This is a required parameter. The default geometry type is a point. By default the geometry is assumed to be in the spatial reference of the image service. You can specify a different spatial reference, by using the JSON structure syntax for geometries.

Syntax:
  • JSON structures: geometryType=<geometryType>&geometry={geometry}
  • Point simple syntax: geometryType=esriGeometryPoint&geometry=<x>,<y>
Examples:
  • geometryType=esriGeometryPoint&geometry={x: -104, y: 35.6}
  • geometryType=esriGeometryPoint&geometry=-104,35.6
geometryType Description: The type of geometry specified by the geometry parameter. The geometry type can be a point or polygon.

Values: esriGeometryPoint | esriGeometryPolygon
mosaicRule Specifies the mosaic rule defining the image sorting order. When mosaic rule is not specified, mosaic rule will default to esriMosaicCenter.

Syntax:
{
  "mosaicMethod" : "<esriMosaicNone | esriMosaicCenter | esriMosaicNadir | esriMosaicViewpoint | 
                     esriMosaicAttribute | esriMosaicLockRaster | esriMosaicNorthwest | esriMosaicSeamline>",
  "where" : "<where>",
  "sortField" : "<sortFieldName>",
  "sortValue" : <sortValue>,
  "ascending" : <true | false>,
  "lockRasterIds" : [<rasterId1>, <rasterId2>],
  "viewpoint" : <point>,
  "fids" : [<fid1>, <fid2>],
  "mosaicOperation" : "<MT_FIRST | MT_LAST | MT_MIN | MT_MAX | MT_MEAN | MT_BLEND>"
}
Example:
{
  "mosaicMethod" : "esriMosaicCenter",
  "sortField" : "Category",
  "ascending" : false
}
pixelSize Description: The pixel level being identified (or the resolution being looked at). If pixel size is not specified, then pixelSize will default to the base resolution of the dataset. The raster at the specified pixel size in the mosaic dataset will be used for identify.

If the pixelSize is not specified, it defaults to the base resolution.

The structure of the pixelSize parameter is the same as the structure of the point object returned by the ArcGIS REST API. In addition to the JSON structure, you can specify the pixel size with a simpler comma-separated syntax.

Syntax:
  • JSON structure: pixelSize={point}
  • Point simple syntax: pixelSize=<x>,<y>
Examples:
  • pixelSize={x: 0.18, y: 0.18}
  • pixelSize=0.18,0.18

Example Usage

Example 1: Identify a single raster Image Service using a point geometry.

http://sampleserver3.arcgisonline.com/ArcGIS/rest/services/Earthquakes/SanAndreasLidar/ImageServer/identify?geometry=%7B%22x%22%3A575505.5%2C%22y%22%3A3733770%7D&geometryType=esriGeometryPoint&mosaicRule=&pixelSize=0.5%2C0.5&f=pjson

Example 2: Identify a mosaic dataset Image Service using a polygon geometry and specify mosaic rule using esriMosaicAttribute method.

http://sampleserver3.arcgisonline.com/ArcGIS/rest/services/Portland/CascadeLandsat/ImageServer/identify?geometry={%22rings%22%3A+[[[-13555360.4191%2C+5911556.581]%2C+%0D%0A++++++++++++[-13489311.5669%2C+5898227.932]%2C+%0D%0A++++++++++++[-13423477.4153%2C+5884426.3329]%2C+%0D%0A++++++++++++[-13602646.9571%2C+5717848.4135]%2C+%0D%0A++++++++++++[-13587119.9125%2C+5781976.6214]%2C+%0D%0A++++++++++++[-13571360.1713%2C+5846543.2654]%2C+%0D%0A++++++++++++[-13555360.4191%2C+5911556.581]%0D%0A]]}&geometryType=esriGeometryPolygon&mosaicRule={%0D%0A++%22mosaicMethod%22+%3A+%22esriMosaicAttribute%22%2C%0D%0A++%22where%22+%3A+%22Name+NOT+LIKE+%27Ov%25%27%22%2C%22sortField%22+%3A+%22Name%22%2C%0D%0A++%22mosaicOperation%22+%3A+%22MT_MAX%22%0D%0A}&pixelSize=&f=html

JSON Response Syntax

{
"objectId" : <objectId>,
"name" : "<name>",
"value" : "<pixelValue>",
"location" : <point>, //the identified location
"properties" : { //the properties (attributes) of the identified object. (returned only when the image service source is a mosaic dataset)
  "name1" : <value1>,
  "name2" : <value2>
},
//catalogItems are returned only when the image service source is a mosaic dataset.
"catalogItems" : {
  "objectIdFieldName" : "<objectIdFieldName>",
  "spatialReference" : <spatialReference>,
  "geometryType" : "<geometryType>",
  "features" : [ 
    <feature1>, <feature2>
  ]
},
//catalogItemVisibilities are returned only when the image service source is a mosaic dataset.
"catalogItemVisibilities" : [ <catalogItem1Visibility>, <catalogItem2Visibility> ]
}

JSON Response Example

{
"objectId" : 22,
"name" : "John Snow",
"value" : "0,1,2",
"location" : {x: -104, y: 35.6},
"properties" : {
   "Value: "10,22,33"
},
"catalogItems" : {
  "objectIdFieldName" : "IMAGEID",
  "spatialReference" : {"wkid" : 4326},
  "geometryType" : "esriGeometryPolygon",
  "features" : [
    {
      "geometry" : {
        "rings" : [ 
           [ [-97.06138,32.837], [-97.06133,32.836], [-97.06124,32.834], [-97.06127,32.832], [-97.06138,32.837] ]
        ]
      },
      "attributes" : {
        "IMAGEID" : 37,
        "OWNER" : "Joe Smith",
        "VALUE" : 94820.37,
        "APPROVED" : true,
        "LASTUPDATE" : 1227663551096
      }
    },
    {
      "geometry" : {
        "rings" : [ 
           [ [-97.06326,32.759], [-97.06298,32.755], [-97.06153,32.749], [-97.06326,32.759] ]
        ]
      },
      "attributes" : {
        "IMAGEID" : 462,
        "OWNER" : "John Doe",
        "VALUE" : 17325.90,
        "APPROVED" : false,
        "LASTUPDATE" : 1227628579430
      }
    }
  ]
},
"catalogItemVisibilities" : [ 0.7, 0.5 ]
}