OpenSearch/docs/reference/ingest/processors/circle.asciidoc

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[role="xpack"]
[testenv="basic"]
[[ingest-circle-processor]]
=== Circle Processor
Converts circle definitions of shapes to regular polygons which approximate them.
[[circle-processor-options]]
.Circle Processor Options
[options="header"]
|======
| Name | Required | Default | Description
| `field` | yes | - | The string-valued field to trim whitespace from
| `target_field` | no | `field` | The field to assign the polygon shape to, by default `field` is updated in-place
| `ignore_missing` | no | `false` | If `true` and `field` does not exist, the processor quietly exits without modifying the document
| `error_distance` | yes | - | The difference between the resulting inscribed distance from center to side and the circle's radius (measured in meters for `geo_shape`, unit-less for `shape`)
| `shape_type` | yes | - | which field mapping type is to be used when processing the circle: `geo_shape` or `shape`
include::common-options.asciidoc[]
|======
image:images/spatial/error_distance.png[]
[source,js]
--------------------------------------------------
PUT circles
{
"mappings": {
"properties": {
"circle": {
"type": "geo_shape"
}
}
}
}
PUT _ingest/pipeline/polygonize_circles
{
"description": "translate circle to polygon",
"processors": [
{
"circle": {
"field": "circle",
"error_distance": 28.0,
"shape_type": "geo_shape"
}
}
]
}
--------------------------------------------------
// CONSOLE
Using the above pipeline, we can attempt to index a document into the `circles` index.
The circle can be represented as either a WKT circle or a GeoJSON circle. The resulting
polygon will be represented and indexed using the same format as the input circle. WKT will
be translated to a WKT polygon, and GeoJSON circles will be translated to GeoJSON polygons.
==== Example: Circle defined in Well Known Text
In this example a circle defined in WKT format is indexed
[source,js]
--------------------------------------------------
PUT circles/_doc/1?pipeline=polygonize_circles
{
"circle": "CIRCLE (30 10 40)"
}
GET circles/_doc/1
--------------------------------------------------
// CONSOLE
// TEST[continued]
The response from the above index request:
[source,js]
--------------------------------------------------
{
"found": true,
"_index": "circles",
"_type": "_doc",
"_id": "1",
"_version": 1,
"_seq_no": 22,
"_primary_term": 1,
"_source": {
"circle": "polygon ((30.000365257263184 10.0, 30.000111397193788 10.00034284530941, 29.999706043744222 10.000213571721195, 29.999706043744222 9.999786428278805, 30.000111397193788 9.99965715469059, 30.000365257263184 10.0))"
}
}
--------------------------------------------------
// TESTRESPONSE[s/"_seq_no": \d+/"_seq_no" : $body._seq_no/ s/"_primary_term": 1/"_primary_term" : $body._primary_term/]
==== Example: Circle defined in GeoJSON
In this example a circle defined in GeoJSON format is indexed
[source,js]
--------------------------------------------------
PUT circles/_doc/2?pipeline=polygonize_circles
{
"circle": {
"type": "circle",
"radius": "40m",
"coordinates": [30, 10]
}
}
GET circles/_doc/2
--------------------------------------------------
// CONSOLE
// TEST[continued]
The response from the above index request:
[source,js]
--------------------------------------------------
{
"found": true,
"_index": "circles",
"_type": "_doc",
"_id": "2",
"_version": 1,
"_seq_no": 22,
"_primary_term": 1,
"_source": {
"circle": {
"coordinates": [
[
[30.000365257263184, 10.0],
[30.000111397193788, 10.00034284530941],
[29.999706043744222, 10.000213571721195],
[29.999706043744222, 9.999786428278805],
[30.000111397193788, 9.99965715469059],
[30.000365257263184, 10.0]
]
],
"type": "polygon"
}
}
}
--------------------------------------------------
// TESTRESPONSE[s/"_seq_no": \d+/"_seq_no" : $body._seq_no/ s/"_primary_term": 1/"_primary_term" : $body._primary_term/]
==== Notes on Accuracy
Accuracy of the polygon that represents the circle is defined as `error_distance`. The smaller this
difference is, the closer to a perfect circle the polygon is.
Below is a table that aims to help capture how the radius of the circle affects the resulting number of sides
of the polygon given different inputs.
The minimum number of sides is `4` and the maximum is `1000`.
[[circle-processor-accuracy]]
.Circle Processor Accuracy
[options="header"]
|======
| error_distance | radius in meters | number of sides of polygon
| 1.00 | 1.0 | 4
| 1.00 | 10.0 | 14
| 1.00 | 100.0 | 45
| 1.00 | 1000.0 | 141
| 1.00 | 10000.0 | 445
| 1.00 | 100000.0 | 1000
|======