diff --git a/.travis.yml b/.travis.yml
index 12cad75b7..9fa8c6ee6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -25,7 +25,7 @@ addons:
       - pandoc
 
 install:
-  - pip install rasterio shapely pandas numpy pweave
+  - pip install shapely>=1.6.0 pandas>=0.25.0 numpy>=1.7 pweave rasterio>=1.0.0
   - wget -O - https://piccolo.link/sbt-1.2.8.tgz | tar xzf -
 
 script:
diff --git a/core/src/main/scala/org/locationtech/rasterframes/ref/GDALRasterSource.scala b/core/src/main/scala/org/locationtech/rasterframes/ref/GDALRasterSource.scala
index 481155f24..62e55313c 100644
--- a/core/src/main/scala/org/locationtech/rasterframes/ref/GDALRasterSource.scala
+++ b/core/src/main/scala/org/locationtech/rasterframes/ref/GDALRasterSource.scala
@@ -78,7 +78,7 @@ object GDALRasterSource extends LazyLogging {
     val _ = new GDALWarp()
     true
   } catch {
-    case _: UnsatisfiedLinkError =>
+    case _:UnsatisfiedLinkError | _:NoClassDefFoundError =>
       logger.warn("GDAL native bindings are not available. Falling back to JVM-based reader for GeoTIFF format.")
       false
   }
diff --git a/core/src/main/scala/org/locationtech/rasterframes/ref/RasterSource.scala b/core/src/main/scala/org/locationtech/rasterframes/ref/RasterSource.scala
index 2d8f1bac8..0fc0691ce 100644
--- a/core/src/main/scala/org/locationtech/rasterframes/ref/RasterSource.scala
+++ b/core/src/main/scala/org/locationtech/rasterframes/ref/RasterSource.scala
@@ -101,18 +101,21 @@ object RasterSource extends LazyLogging {
     ExpressionEncoder()
   }
 
+  def apply(source: String): RasterSource = apply(new URI(source))
+
   def apply(source: URI): RasterSource =
     rsCache.get(
-      source.toASCIIString, _ => source match {
-        case IsGDAL()          => GDALRasterSource(source)
-        case IsHadoopGeoTiff() =>
-          // TODO: How can we get the active hadoop configuration
-          // TODO: without having to pass it through?
-          val config = () => new Configuration()
-          HadoopGeoTiffRasterSource(source, config)
-        case IsDefaultGeoTiff() => JVMGeoTiffRasterSource(source)
-        case s                  => throw new UnsupportedOperationException(s"Reading '$s' not supported")
-      }
+      source.toASCIIString, _ =>
+        source match {
+          case IsGDAL() => GDALRasterSource(source)
+          case IsHadoopGeoTiff() =>
+            // TODO: How can we get the active hadoop configuration
+            // TODO: without having to pass it through?
+            val config = () => new Configuration()
+            HadoopGeoTiffRasterSource(source, config)
+          case IsDefaultGeoTiff() => JVMGeoTiffRasterSource(source)
+          case s => throw new UnsupportedOperationException(s"Reading '$s' not supported")
+        }
     )
 
   object IsGDAL {
@@ -122,6 +125,8 @@ object RasterSource extends LazyLogging {
 
     val gdalOnlyExtensions = Seq(".jp2", ".mrf", ".hdf", ".vrt")
 
+    val blacklistedSchemes = Seq("s3a", "s3n", "wasbs")
+
     def gdalOnly(source: URI): Boolean =
       if (gdalOnlyExtensions.exists(source.getPath.toLowerCase.endsWith)) {
         require(GDALRasterSource.hasGDAL, s"Can only read $source if GDAL is available")
@@ -130,26 +135,43 @@ object RasterSource extends LazyLogging {
 
     /** Extractor for determining if a scheme indicates GDAL preference.  */
     def unapply(source: URI): Boolean = {
+
+      lazy val schemeIsNotHadoop = Option(source.getScheme())
+        .filter(blacklistedSchemes.contains)
+        .isEmpty
+
       lazy val schemeIsGdal = Option(source.getScheme())
-        .exists(_.startsWith("gdal"))
+        .exists(_ == "gdal") && schemeIsNotHadoop
+
+      (gdalOnly(source) && schemeIsNotHadoop) ||
+        (GDALRasterSource.hasGDAL &&
+          (preferGdal && schemeIsGdal) ||
+          (preferGdal && schemeIsNotHadoop)
+        )
 
-      gdalOnly(source) || ((preferGdal || schemeIsGdal) && GDALRasterSource.hasGDAL)
     }
   }
 
   object IsDefaultGeoTiff {
-    def unapply(source: URI): Boolean = source.getScheme match {
-      case "file" | "http" | "https" | "s3" => true
-      case null | ""                        ⇒ true
-      case _                                => false
+    import IsGDAL.gdalOnly
+    def unapply(source: URI): Boolean = {
+      if (gdalOnly(source)) false
+      else source.getScheme match {
+        case "file" | "http" | "https" | "s3" => true
+        case null | ""                        ⇒ true
+        case _                                => false
+      }
     }
   }
 
   object IsHadoopGeoTiff {
-    def unapply(source: URI): Boolean = source.getScheme match {
-      case "hdfs" | "s3n" | "s3a" | "wasb" | "wasbs" => true
-      case _                                         => false
-    }
+    import IsGDAL.gdalOnly
+    def unapply(source: URI): Boolean =
+      if (gdalOnly(source)) false
+      else source.getScheme match {
+        case "hdfs" | "s3n" | "s3a" | "wasb" | "wasbs" => true
+        case _                                         => false
+      }
   }
 
   trait URIRasterSource { _: RasterSource =>
diff --git a/core/src/test/scala/org/locationtech/rasterframes/ref/RasterSourceSpec.scala b/core/src/test/scala/org/locationtech/rasterframes/ref/RasterSourceSpec.scala
index 6b3371ea3..de0aa1cb3 100644
--- a/core/src/test/scala/org/locationtech/rasterframes/ref/RasterSourceSpec.scala
+++ b/core/src/test/scala/org/locationtech/rasterframes/ref/RasterSourceSpec.scala
@@ -156,7 +156,6 @@ class RasterSourceSpec extends TestEnvironment with TestData {
         gdal.layoutExtents(dims) should contain allElementsOf jvm.layoutExtents(dims)
       }
 
-
       it("should support vsi file paths") {
         val archivePath = geotiffDir.resolve("L8-archive.zip")
         val archiveURI = URI.create("gdal://vsizip/" + archivePath.toString + "/L8-RGB-VA.tiff")
@@ -173,6 +172,16 @@ class RasterSourceSpec extends TestEnvironment with TestData {
         gdal.extent should be (jvm.extent)
         gdal.cellSize should be(jvm.cellSize)
       }
+
+      it("should choose correct delegate for scheme and file"){
+        val hdfsSchemeTif = RasterSource("s3n://bucket/prefix/raster.tif")
+        val easySchemeTif = RasterSource("s3://bucket/prefix/raster.tif")  // should interpret as /vsis3/
+        lazy val hdfsSchemeJp2 = RasterSource("s3n://s22s-test-geotiffs/luray_snp/B04.jp2")  // can't read with hadoop reader
+
+        hdfsSchemeTif should matchPattern {case HadoopGeoTiffRasterSource(_, _) ⇒}
+        easySchemeTif should matchPattern {case GDALRasterSource(_) ⇒}
+        assertThrows[UnsupportedOperationException](hdfsSchemeJp2.bandCount)
+      }
     }
   }
 
diff --git a/pyrasterframes/src/main/python/tests/RasterFunctionsTests.py b/pyrasterframes/src/main/python/tests/RasterFunctionsTests.py
index 2a57cf356..fe2909a32 100644
--- a/pyrasterframes/src/main/python/tests/RasterFunctionsTests.py
+++ b/pyrasterframes/src/main/python/tests/RasterFunctionsTests.py
@@ -300,9 +300,6 @@ def test_render_composite(self):
         # Look for the PNG magic cookie
         self.assertEqual(png_bytes[0:8], bytearray([0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A]))
 
-
-
-
     def test_rf_interpret_cell_type_as(self):
         from pyspark.sql import Row
         from pyrasterframes.rf_types import Tile