jiayuasu opened a new pull request, #3275: URL: https://github.com/apache/sedona/pull/3275
## Did you read the Contributor Guide? - Yes, I have read the [Contributor Rules](https://sedona.apache.org/latest/community/rule/) and [Contributor Development Guide](https://sedona.apache.org/latest/community/develop/) ## Is this PR related to a ticket? - No: this is a documentation update. The PR name follows the format `[DOCS] my subject` ## What changes were proposed in this PR? Add a blog post, "Find the Middle of the Mississippi", that extracts a river centerline from Sentinel-2 pixels with Sedona's raster operators and `ST_ApproximateMedialAxis`. The pipeline: read the green and NIR bands of a Sentinel-2 scene from the public `sentinel-cogs` bucket as 512 px tiles, compute a water index in a Python raster UDF, downsample with `RS_Resample`, vectorize wet pixels with `RS_PixelAsPolygons`, dissolve per tile and then globally with `ST_Union_Aggr`, split into water bodies with `ST_Dump`, clean the largest body (buffer smoothing, `ST_SimplifyPreserveTopology`, exterior ring only), run `ST_ApproximateMedialAxis` and `ST_LineMerge`, prune side branches with a SQL rule, and measure length, sinuosity, and a width profile with `ST_LineInterpolatePoint` and `ST_Distance`. A section explains the relationship to `ST_StraightSkeleton`, a section covers distribution, and a closing section previews the road-network follow-up. Includes four images generated from the run's real outputs: a cover, a three-step figure over the imagery, a straight-skeleton vs medial-axis comparison, and a width profile chart. ## How was this patch tested? - Every snippet ran against the released artifacts: `pip install apache-sedona==1.9.1` with `sedona-spark-shaded-3.5_2.12:1.9.1`, `geotools-wrapper:1.9.1-33.5`, and `hadoop-aws:3.3.4` from Maven Central, reading `s3a://sentinel-cogs` anonymously. - All numbers in the post (410 tiles, 5,429 water bodies, 17,530 to 474 vertices, 147.6 km centerline, sinuosity 1.43, width statistics, 56 s end to end) are the measured output of those runs; the console blocks are pasted from them. - `pre-commit` passes, including the manual-stage `oxipng` hook on all PNGs (idempotent on the second run). - Verified the rendered page with `mkdocs serve`: images resolve, code highlighting works, the blog star-CTA hook is appended. ## Did this PR include necessary documentation updates? - Yes, I have updated the documentation. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
