kanchanchy commented on code in PR #612:
URL: https://github.com/apache/incubator-sedona/pull/612#discussion_r853636330
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sql/src/main/scala/org/apache/spark/sql/sedona_sql/io/GeotiffFileFormat.scala:
##########
@@ -101,4 +126,123 @@ private[spark] class GeotiffFileFormat extends FileFormat
with DataSourceRegiste
}
}
}
+
+ private def isValidGeoTiffSchema(options: Map[String, String], dataSchema:
StructType): Boolean = {
+ val colImage = options.getOrElse("key_image", "image")
+ val fields = dataSchema.fieldNames
+ if (fields.contains(colImage) ){
+ val schemaFields =
dataSchema.fields(dataSchema.fieldIndex(colImage)).dataType.asInstanceOf[StructType]
+ if (schemaFields.fieldNames.length != 6) return false
+ }
+ else {
+ if (fields.length != 6) return false
+ }
+ true
+ }
+
+}
+
+// class for writing geoTiff images
+private class GeotiffFileWriter(savePath: String,
+ options: Map[String, String],
+ dataSchema: StructType,
+ context: TaskAttemptContext) extends
OutputWriter {
+
+ // set writing parameters
+ private val DEFAULT_WRITE_PARAMS: GeoTiffWriteParams = new
GeoTiffWriteParams()
+ DEFAULT_WRITE_PARAMS.setCompressionMode(ImageWriteParam.MODE_EXPLICIT)
+ DEFAULT_WRITE_PARAMS.setCompressionType("LZW")
+ DEFAULT_WRITE_PARAMS.setCompressionQuality(0.75F)
+ DEFAULT_WRITE_PARAMS.setTilingMode(ImageWriteParam.MODE_EXPLICIT)
+ DEFAULT_WRITE_PARAMS.setTiling(512, 512)
+
+ private val hfs = new Path(savePath).getFileSystem(context.getConfiguration)
+
+ override def write(row: InternalRow): Unit = {
+ // retrieving the metadata of a geotiff image
+ var rowFields: InternalRow = row
+ var schemaFields: StructType = dataSchema
+ val fields = dataSchema.fieldNames
+
+ val colImage = options.getOrElse("key_image", "image")
+ val colOrigin = options.getOrElse("key_origin", "origin")
+ val colBands = options.getOrElse("key_n_bands", "nBands")
+ val colWidth = options.getOrElse("key_width", "width")
+ val colHeight = options.getOrElse("key_height", "height")
+ val colWkt = options.getOrElse("key_wkt", "wkt")
+ val colData = options.getOrElse("key_data", "data")
+
+ if (fields.contains(colImage)) {
+ schemaFields =
dataSchema.fields(dataSchema.fieldIndex(colImage)).dataType.asInstanceOf[StructType]
+ rowFields = row.getStruct(dataSchema.fieldIndex(colImage), 6)
+ }
+
+ val tiffOrigin = rowFields.getString(schemaFields.fieldIndex(colOrigin))
+ val tiffBands = rowFields.getInt(schemaFields.fieldIndex(colBands))
+ val tiffWidth = rowFields.getInt(schemaFields.fieldIndex(colWidth))
+ val tiffHeight = rowFields.getInt(schemaFields.fieldIndex(colHeight))
+ val tiffGeometry = rowFields.getString(schemaFields.fieldIndex(colWkt))
+ val tiffData =
rowFields.getArray(schemaFields.fieldIndex(colData)).toDoubleArray()
+
+ // create a writable raster object
+ val raster = RasterFactory.createBandedRaster(DataBuffer.TYPE_DOUBLE,
tiffWidth, tiffHeight, tiffBands, null)
+
+ // extract the pixels of the geotiff image and write to the writable raster
+ val pixelVal = Array.ofDim[Double](tiffBands)
+ for (i <- 0 until tiffHeight) {
+ for (j <- 0 until tiffWidth) {
+ for (k <- 0 until tiffBands) {
+ pixelVal(k) = tiffData(tiffHeight*tiffWidth*k + i * tiffWidth + j)
+ }
+ raster.setPixel(j, i, pixelVal)
+ }
+ }
+
+ // CRS is always fixed to EPSG:4326
+ val crs = CRS.decode("EPSG:4326", true)
Review Comment:
@jiayuasu When writing a GeoTiff, we usually need to pass the CRS as a
parameter when creating the reference envelop. It indicates the CRS of the
polygon representing the image source. So, we need to pass the correct CRS info
in line 208
[here](https://github.com/apache/incubator-sedona/pull/612/files/6fe92ec5c2736f8cbd6d9dd381380a1f5ac6aab8#diff-9afdfa8529cd2458278c7f0a2abb09bfaaa0599fe312b02ff6085d72c49fdda2).
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