Surface placement mode involves placing your 3D content on a flat surface in your environment.

Devices supported include the following:

• Microsoft HoloLens 2
• Apple iPhones & iPads
• Android phones and tablets that fully support ARCore: 

The best practices to achieve desired results:

• Point the device camera at the desired flat surface approximately 2 meters away.
  • Be in a well lit space.
  • Flat surfaces with no clutter work best.
  • Avoid reflective and dark surfaces.
• If your project is setup to use a customized placeholder content, make sure you see the placeholder before placing content on surface.
• Use the "Place Content" menu option to reposition your content at anytime.