Buffer for resample by only half a pixel

.gitignore

@@ -48,3 +48,6 @@ metastore_db/
 
 spark/src/test/resources/vlm/*catalog*
 
+
+# vscode
+.vscode

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Changed
 - Fix `Encoder[GeometryCollection]` including subclasses of GeometryCollection twice in the json
    (MultiPolygon, Multipoint,MultiLinestring) [#3167](https://github.com/locationtech/geotrellis/issues/3167)
+-Fix `LayoutTileSource` buffer should only be 1/2 a cellsize to avoid going out of bounds and creating `NODATA` values [#3302](https://github.com/locationtech/geotrellis/pull/3302)
 - Remove unused allocation from CroppedTile [#3297](https://github.com/locationtech/geotrellis/pull/3297)
 
 ## [3.5.0] - 2020-08-18

layer/src/test/scala/geotrellis/layer/LayoutTileSourceSpec.scala

@@ -244,5 +244,37 @@ class LayoutTileSourceSpec extends AnyFunSpec with RasterMatchers {
         t.dimensions shouldBe Dimensions(256, 256)
       }
     }
+
+    it("should read reprojected and tiled to layout source without nodata stripe // see issue-3299") {
+      val path = Resource.path("vlm/nodata-row.tif")
+      val testZoomLevel = 19
+      val rs = GeoTiffRasterSource(path)
+
+      val scheme = ZoomedLayoutScheme(WebMercator)
+      val layout = scheme.levelForZoom(testZoomLevel).layout
+
+      val extent: Extent = rs.extent.reproject(rs.crs, WebMercator)
+      val SpatialKey(x, y) = layout.mapTransform(extent.center)
+
+      val neighborhood = for {
+        col <- ((x - 2) until (x + 2)).toList
+        row <- ((y - 2) until (y + 2)).toList
+      } yield (col, row)
+
+      def checkExtent(col: Int, row: Int, rs: RasterSource): Unit = {
+        val tile = rs
+          .tileToLayout(layout)
+          .read(SpatialKey(col, row), List(0))
+          .get
+          .band(0)
+        val arr = tile.toArray
+        val ones = tile.mapIfSet(i => 1).toArray()
+        ones.sum shouldBe(arr.size)
+      }
+
+      neighborhood map {
+        case (x, y) => checkExtent(x, y, rs)
+      }
+    }
   }
 }

raster/src/main/scala/geotrellis/raster/geotiff/GeoTiffResampleRasterSource.scala

@@ -111,9 +111,10 @@ class GeoTiffResampleRasterSource(
       targetPixelBounds <- queryPixelBounds.intersection(this.dimensions)
     } yield {
       val targetExtent = gridExtent.extentFor(targetPixelBounds)
-      // buffer the targetExtent to read a buffered area from the source tiff
+      // Buffer the targetExtent to read a buffered area from the source tiff
       // so the resample would behave properly on borders
-      val bufferedTargetExtent = targetExtent.buffer(cellSize.width, cellSize.height)
+      // Buffer by half of CS to avoid resampling out of bounds
+      val bufferedTargetExtent = targetExtent.buffer(cellSize.width / 2, cellSize.height / 2)
       val sourcePixelBounds = closestTiffOverview.rasterExtent.gridBoundsFor(bufferedTargetExtent)
       val targetRasterExtent = RasterExtent(targetExtent, targetPixelBounds.width.toInt, targetPixelBounds.height.toInt)
       (sourcePixelBounds, targetRasterExtent)