Finish reprojection doc.

docs/reproject.rst

@@ -5,13 +5,54 @@ Rasterio can map the pixels of a destination raster with an associated coordinat
 reference system and transform to the pixels of a source image with a different
 coordinate reference system and transform. This process is known as reprojection.
 
-Rasterio's ``rasterio.warp.reproject()`` is a very geospatial specific analog to
+Rasterio's ``rasterio.warp.reproject()`` is a very geospatial-specific analog to
 SciPy's ``scipy.ndimage.interpolation.geometric_transform()`` [1]_.
 
-Result
-------
+The code below reprojects between two arrays, using no pre-existing GIS datasets.
+``rasterio.warp.reproject()`` has two positional arguments: source and destination.
+The remaining keyword arguments parameterize the reprojection transform.
 
-https://a.tiles.mapbox.com/v3/sgillies.hfek2oko/page.html?secure=1#6/0.000/0.033
+.. code-block:: python
+
+    import numpy
+    import rasterio
+    from rasterio.warp import reproject, RESAMPLING
+
+    with rasterio.drivers():
+
+        # Consider a 512 x 512 raster centered on 0 degrees E and 0 degrees N
+        # with each pixel covering 15".
+        src_shape = (512, 512)
+        src_transform = [-256.0/240, 1.0/240, 0.0, 256.0/240, 0.0, -1.0/240]
+        src_crs = {'init': 'EPSG:4326'}
+        source = numpy.ones(src_shape, numpy.uint8)*255
+
+        # Prepare to reproject this rasters to a 1024 x 1024 dataset in
+        # Web Mercator (EPSG:3857) with origin at 0.0, 0.0.
+        dst_shape = (1024, 1024)
+        dst_transform = [-237481.5, 425.0, 0.0, 237536.4, 0.0, -425.0]
+        dst_crs = {'init': 'EPSG:3857'}
+        destination = numpy.zeros(dst_shape, numpy.uint8)
+
+        reproject(
+            source, 
+            destination, 
+            src_transform=src_transform,
+            src_crs=src_crs,
+            dst_transform=dst_transform,
+            dst_crs=dst_crs,
+            resampling=RESAMPLING.nearest)
+
+        # Assert that the destination is only partly filled.
+        assert destination.any()
+        assert not destination.all()
+
+See `examples/reproject.py <https://github.com/mapbox/rasterio/blob/master/examples/reproject.py>`__ for code that writes the destination array to a GeoTIFF file. I've 
+uploaded the resulting file to a Mapbox map to demonstrate that the reprojection is
+correct: https://a.tiles.mapbox.com/v3/sgillies.hfek2oko/page.html?secure=1#6/0.000/0.033
+
+References
+----------
 
 .. [1] http://docs.scipy.org/doc/scipy/reference/generated/scipy.ndimage.interpolation.geometric_transform.html#scipy.ndimage.interpolation.geometric_transform
 

examples/reproject.py

@@ -5,7 +5,7 @@ import tempfile
 
 import numpy
 import rasterio
-from rasterio.warp import reproject
+from rasterio.warp import reproject, RESAMPLING
 
 tempdir = '/tmp'
 tiffname = os.path.join(tempdir, 'example.tif')
@@ -27,9 +27,13 @@ with rasterio.drivers():
     destination = numpy.zeros(dst_shape, numpy.uint8)
 
     reproject(
-        source, destination, 
-        src_transform, src_crs,
-        dst_transform, dst_crs)
+        source, 
+        destination, 
+        src_transform=src_transform,
+        src_crs=src_crs,
+        dst_transform=dst_transform,
+        dst_crs=dst_crs,
+        resampling=RESAMPLING.nearest)
 
     # Assert that the destination is only partly filled.
     assert destination.any()

rasterio/warp.py

@@ -1,4 +1,4 @@
 """Raster warping and reprojection"""
 
 import rasterio
-from rasterio._warp import reproject
+from rasterio._warp import reproject, RESAMPLING