A method for a placement of a virtual object of an augmented or mixed reality application in a real-world 3D environment, comprises: selecting (14), at a runtime of the augmented or mixed reality application, one of a finite set of at least two candidate insertion areas predetermined in the real-world 3D environment for the placement of the virtual object in the real-world 3D environment, based on criteria combining, for each of the candidate insertion areas, relationships between each of: the real-world 3D environment, the virtual object considered with respect to a placement of that virtual object in that candidate insertion area, and a user position; and inserting (14) the virtual object in the selected candidate insertion area.