Using the HoloToolKit I was able to better understand how spatial mapping is done with the HoloLens device. In this example it shows how to manage spatial mapping by bye using the Spatial Mapping Observer script and Object Surface Observer script. Take a look at the video to see how the HoloLens can map and display the different surfaces in your play environment.
Later I will give tutorials on how to use this with placing 3d assets in your environment. Their are also tutorials on the Microsoft holographic academy site located here.
NOTE: The files you download from the holographic academy slightly differ from the code that is from the GitHub repository. You can download the HoloToolKit from here.
Here are a couple of videos of me messing around with the HoloToolKit SpatialUnderstanding Example:
The Spatial Mapping Component is an interesting example it shows how you can use Unity's built in Spatial Mapping Collider and Renderer scripts to do some very basic but interesting Spatial Mapping with simple physics.
Later I'll go into how to manipulate these examples to make them custom tailored for your application.
If you have any questions you can contact me here.