Slope Angle Visualisation (Shading Map)

This is not something I have ever been asked for or even considered, but it is an interesting idea.

I often measure large housing projects and it is often a condition that gardens do not exceed a particular incline (resulting in the design of many retaining walls). With this in mind, it would be useful to have a visual tool which shaded by incline. It might come in helpful when performing a value engineering exercise to see what affect the removal of retaining walls has on a site to see if the inclines are still at acceptable levels.