Shaded Relief Map

Shaded relief maps are raster maps based on grid files. These maps use colors to indicate the local orientation of the surface relative to a user-defined light source direction. Surfer determines the orientation of each grid cell and calculates reflectance of a point light source on the grid surface. The light source can be thought of as the sun shining on a topographic surface. Portions of the surface that face away from the light source reflects less light toward the viewer, and thus appear darker.

 

This shaded relief map shows Telluride, Colorado

with the default shaded relief shading and gradient settings.

 

The colors on a shaded relief map are based on the reflectance from the grid surface. Reflectance values range from zero to one. A reflectance value of zero means that no light is reflected toward the viewer. A reflectance value of one means that all incident light is reflected toward the viewer.

 

Because colors are assigned to entire grid cells, sparse grids (grids with relatively few rows and columns) are poor candidates for shaded relief maps. Shaded relief maps based on grids with too few cells look blocky or fuzzy. The Spline Smooth or Mosaic commands can be used to make a denser grid from an existing grid.

 

You can assign colors to represent the various reflectance values. Colors between the assigned values are automatically blended to make a smooth gradation. Blanked regions on shaded relief maps are shown as a separate color.

 

Any color scheme selected for a shaded relief map may be used with any other shaded relief map, even if the associated grid files result in significantly different orientations of the surface relative to the light source. Color schemes can be saved in color spectrum .CLR files.

 

Creating a Shaded Relief Map

To create a new shaded relief map:

  1. Click the Home | New Map | Speciality | Shaded Relief command.

  2. Select a grid file in the Open Grid dialog and click Open.

The map is created with the default settings.

 

Editing an Existing Shaded Relief Map

To change the features of the shaded relief map, click once on the shaded relief layer in the plot window or in the Contents window to select it. The properties are displayed in the Properties window.

 

Adding a Map Layer

When shaded relief maps are created, they are independent of other maps in the plot window. For example, creating a shaded relief map while a contour map is present in the plot window yields two separate maps, each with its own set of axes and scaling parameters. To create a single map with the shaded relief layer on the contour layer, select both maps by clicking the Home | Selection | Select All command.  Overlay the maps using the Map Tools | Map Tools | Overlay Maps command.

 

Alternatively, you can add the shaded relief map directly to the existing contour map by creating the shaded relief map using the Home | Add to Map | Layer | Shaded Relief or Map Tools | Add to Map | Layer | Shaded Relief command. This automatically adds the shaded relief map to the contour map axes.

 

Another alternative, is to create both maps using the Home | New Map commands.  Then, select one map and drag the map layer to the other map object.  This is equivalent to using the Overlay Maps command  to overlay maps. For example, create a contour map with the Home | New Map | Contour command. Create the shaded relief map using the Home | New Map | Speciality | Shaded Relief command. This creates two separate maps. Click on the shaded relief map, hold down the left mouse button, and drag the shaded relief map into the contour map. A single map with two map layers, using one set of axes and scaling parameters is created.

 

Shaded relief maps cannot be added as a map layer to 3D wireframe maps, but a shaded relief map can be added to any other map layer, including 3D surface maps.

 

Shaded Relief Layer Properties

The shaded relief map layer properties contains the following pages:

General

Layer

Coordinate System

Info

 

Map Properties

The map properties contains the following pages:

View

Scale

Limits

Frame

Coordinate System

Info

 

 

See Also

Shading Methods

Introduction to Map Layers

Overlaying Maps

Map Add

Properties