--- layout: example.html title: Region Growing shortdesc: Grow a region from a seed pixel docs: >

Click a region on the map. The computed region will be red.

This example uses a `ol/source/Raster` to generate data based on another source. The raster source accepts any number of input sources (tile or image based) and runs a pipeline of operations on the input data. The return from the final operation is used as the data for the output source.

In this case, a single tiled source of imagery data is used as input. The region is calculated in a single "image" operation using the "seed" pixel provided by the user clicking on the map. The "threshold" value determines whether a given contiguous pixel belongs to the "region" - the difference between a candidate pixel's RGB values and the seed values must be below the threshold.

This example also shows how an additional function can be made available to the operation.

tags: "raster, region growing" cloak: - key: As1HiMj1PvLPlqc_gtM7AqZfBL8ZL3VrjaS3zIb22Uvb9WKhuJObROC-qUpa81U5 value: Your Bing Maps Key from http://www.bingmapsportal.com/ here ---

Threshold: |