Add visual test of GDAL overviews with filter-factor=2.0

Author: talaj

images/gdal-overview-bilinear-scaling-filter-factor-256-256-1.0-agg-reference.png

@@ -0,0 +1,23 @@
+<Map>
+    <Parameters>
+        <Parameter name="sizes">256,256</Parameter>
+    </Parameters>
+
+    <Style name="raster">
+        <Rule>
+            <!--
+            This test must not render from given overviews as billinear scaling
+            is using filter-factor 2.0 by default.
+            -->
+            <RasterSymbolizer scaling="bilinear" />
+        </Rule>
+    </Style>
+
+    <Layer name="dataraster">
+        <StyleName>raster</StyleName>
+        <Datasource>
+            <Parameter name="file">../../data/tiff/overview-test.tif</Parameter>
+            <Parameter name="type">gdal</Parameter>
+        </Datasource>
+    </Layer>
+</Map>