# Transform - Tiles: Slope

The Slope template appears in the template list when a raster tile field, of type Tile, has been picked in the Transform pane.  The template computes slope and other characteristics related to tilt, aspect and curvature of a surface.

Tech Tip:  Manifold runs CPU parallel and also GPU parallel, as discussed in the GPGPU topic.   Having a GPU can make a huge difference in speed for many transforms that work with raster images, for example, when computing Curvature or Slope or Aspect using a radius of 3 or more.  Manifold running without a GPU installed will automatically use CPU parallelism instead for spectacular parallel speed, but with a GPU installed Manifold can often run dramatically faster.    Installing at least one, inexpensive NVIDIA GPU card in our systems allows such operations to run with astonishing speed, at times reducing computations from minutes to seconds or from hours to seconds.  A wide range of GPU cards costing from under \$100 to around \$250 will make a spectacular difference.

## Notes

Sample image - Many illustrations for transforms for raster images use an Elevation Raster sample image, a version of the formatted example of importing an SDTS format DEM from the Example: Import DDF SDTS DEM Raster File  topic.   The example project may be downloaded from the Downloads page on the Manifold web site.

Everything Math - For a handy reference to anything in mathematics, see the Wolfram MathWorld site.   Thank you, Wolfram!

Transform Pane

Transform Reference

Transform - Tiles

Example: Enhance Terrain with Curvatures -  We enhance a terrain showing Crater Lake, Oregon, by using mean curvature calculation to bring out details.   The example uses a 4 GB project containing a large terrain elevation surface.  Using a point-and-click dialog with no SQL, we apply automatic CPU parallelism and GPU parallelism to absolutely crush a task in two and a half minutes that would take non-parallel software days.

Example: Find Flatter Areas in Terrain - In this example we find flatter areas in terrain that are suitable for airports, better farm land, or for hobbies like falconing. We import an SRTM file and create a map using Bing Streets as a background layer.  With a few clicks we then create a Slope layer from the terrain elevation layer and then we color the Slope layer so that regions with slope less than 5 degrees are transparent, allowing the underlying base map to show through in "flat" regions.