kanchanchy commented on code in PR #612:
URL: https://github.com/apache/incubator-sedona/pull/612#discussion_r853439658
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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:
Got it. I have one more question. If the user doesn't specify the
'readToCRS' option during reading, what would be the target default value? In
that case, should we use CRS available in the GeoTiff or readFromCRS as the
target value?
Also, is writeToCRS a mandatory option? If optional, what should be the
default value?
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