Refined handling of single vs multiple bands in SlippyExport.

Signed-off-by: Simeon H.K. Fitch <[email protected]>

Author: metasim

core/src/main/scala/astraea/spark/rasterframes/util/MultibandRender.scala

@@ -63,6 +63,9 @@ object MultibandRender {
 
   /** Base type for Rendering profiles. */
   trait Profile {
+    /** Expected number of bands. */
+    def expectedBands: Int = 3
+
     /** Value from -255 to 255 */
     def brightness: Int = 0
     /** Value from  -255 to 255 */
@@ -102,6 +105,8 @@ object MultibandRender {
       compressRange _ andThen colorAdjust
 
     def render(tile: MultibandTile) = {
+      require(expectedBands <= tile.bandCount, s"Need at least $expectedBands bands (${tile.bandCount} provided).")
+
       val r = applyAdjustment(red(tile))
       val g = applyAdjustment(green(tile))
       val b = applyAdjustment(blue(tile))
@@ -128,8 +133,11 @@ object MultibandRender {
   }
 
   case class ColorRampProfile(ramp: ColorRamp) extends Profile {
+    override def expectedBands: Int = 1
     // Are there other ways to use the other bands?
-    override def render(tile: MultibandTile): Png =
+    override def render(tile: MultibandTile): Png = {
+      require(tile.bandCount >= 1, s"Need at least 1 band")
       applyAdjustment(tile.band(0)).renderPng(ramp)
+    }
   }
 }

docs/src/main/tut/release-notes.md

@@ -2,6 +2,12 @@
 
 ## 0.7.x
 
+### 0.7.1
+
+* Fixed ColorRamp pipeline in MultibandRender
+* Fixed Python wrapper for `explodeTiles`
+
+
 ### 0.7.0
 
 * Now an incubating project under Eclipse Foundation LocationTech! GitHub repo moved to [locationtech/rasterframes](https://github.com/locationtech/rasterframes).

experimental/src/main/scala/astraea/spark/rasterframes/experimental/slippy/SlippyExport.scala

@@ -24,7 +24,6 @@ import java.io.PrintStream
 import java.net.URI
 
 import astraea.spark.rasterframes._
-import astraea.spark.rasterframes.util.MultibandRender.ColorRampProfile
 import astraea.spark.rasterframes.util._
 import geotrellis.proj4.{LatLng, WebMercator}
 import geotrellis.raster._
@@ -116,13 +115,13 @@ trait SlippyExport extends MethodExtensions[RasterFrame]{
 
     val (zoom, reprojected) = inputRDD.reproject(WebMercator, layoutScheme, Bilinear)
     val writer = new HadoopSlippyTileWriter[MultibandTile](dest.toASCIIString + "/" + tileDirName, "png")({ (_, tile) =>
-      require(tile.bandCount >= 3 || renderer.isInstanceOf[ColorRampProfile],
-        "Single-band and dual-band RasterFrames require a ColorRampProfile for rendering")
+      //require(tile.bandCount >= 3 || renderer.isInstanceOf[ColorRampProfile],
+      //  "Single-band and dual-band RasterFrames require a ColorRampProfile for rendering")
       val png = renderer.render(tile)
       png.bytes
     })
 
-    val center = reprojected.metadata.extent.center.reproject(WebMercator, LatLng)
+    val center = reprojected.metadata.extent.center
 
     SlippyExport.writeHtml(dest, sc.hadoopConfiguration, Map(
       "maxZoom" -> zoom.toString,