jiayuasu commented on code in PR #2661:
URL: https://github.com/apache/sedona/pull/2661#discussion_r2825951287
##########
spark/common/src/main/scala/org/apache/spark/sql/execution/datasources/geoparquet/GeoParquetMetaData.scala:
##########
@@ -137,6 +138,57 @@ object GeoParquetMetaData {
compactJson(serializedGeoObject)
}
+ /**
+ * Default SRID for GeoParquet files where the CRS field is omitted. Per the
GeoParquet spec,
+ * omitting the CRS implies OGC:CRS84, which is equivalent to EPSG:4326.
+ */
+ val DEFAULT_SRID: Int = 4326
+
+ /**
+ * Extract SRID from a GeoParquet CRS metadata value.
+ *
+ * Per the GeoParquet specification:
+ * - If the CRS field is absent (None), the CRS is OGC:CRS84 (EPSG:4326).
+ * - If the CRS field is explicitly null, the CRS is unknown (SRID 0).
+ * - If the CRS field is a PROJJSON object with an "id" containing
"authority" and "code", the
+ * EPSG code is used as the SRID.
+ *
+ * @param crs
+ * The CRS field from GeoParquet column metadata.
+ * @return
+ * The SRID corresponding to the CRS. Returns 4326 for omitted CRS, 0 for
null or unrecognized
+ * CRS, and the EPSG code for PROJJSON with an EPSG identifier.
+ */
+ def extractSridFromCrs(crs: Option[JValue]): Int = {
+ crs match {
+ case None =>
+ // CRS omitted: default to OGC:CRS84 (EPSG:4326) per GeoParquet spec
+ DEFAULT_SRID
+ case Some(JNull) =>
+ // CRS explicitly null: unknown CRS
+ 0
+ case Some(projjson) =>
+ // Use proj4sedona to extract authority and code from PROJJSON
+ try {
+ val jsonStr = compactJson(projjson)
+ val result = new Proj(jsonStr).toAuthority()
+ if (result != null && result.length == 2) {
+ result(0) match {
+ case "EPSG" =>
+ try { result(1).toInt }
+ catch { case _: NumberFormatException => 0 }
+ case "OGC" if result(1) == "CRS84" => 4326
+ case _ => 0
+ }
+ } else {
+ 0
+ }
+ } catch {
+ case _: Exception => 0
+ }
Review Comment:
fixed
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