Circle Processor
editCircle Processor
editConverts circle definitions of shapes to regular polygons which approximate them.
Table 34. Circle Processor Options
Name | Required | Default | Description |
---|---|---|---|
|
yes |
- |
The string-valued field to trim whitespace from |
|
no |
|
The field to assign the polygon shape to, by default |
|
no |
|
If |
|
yes |
- |
The difference between the resulting inscribed distance from center to side and the circle’s radius (measured in meters for |
|
yes |
- |
which field mapping type is to be used when processing the circle: |
|
no |
- |
Conditionally execute this processor. |
|
no |
- |
Handle failures for this processor. See Handling Failures in Pipelines. |
|
no |
|
Ignore failures for this processor. See Handling Failures in Pipelines. |
|
no |
- |
An identifier for this processor. Useful for debugging and metrics. |
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" } } ] }
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
editIn this example a circle defined in WKT format is indexed
PUT circles/_doc/1?pipeline=polygonize_circles { "circle": "CIRCLE (30 10 40)" } GET circles/_doc/1
The response from the above index request:
{ "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))" } }
Example: Circle defined in GeoJSON
editIn this example a circle defined in GeoJSON format is indexed
PUT circles/_doc/2?pipeline=polygonize_circles { "circle": { "type": "circle", "radius": "40m", "coordinates": [30, 10] } } GET circles/_doc/2
The response from the above index request:
{ "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" } } }
Notes on Accuracy
editAccuracy 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
.