The following image illustrates a more traditional target-based AR. The device camera captures a frame of video. The software analyzes the frame looking for a familiar target, such as a pre-programmed marker, using a technique called photogrammetry. As part of target detection, its deformation (for example, size and skew) is analyzed to determine its distance, position, and orientation relative to the camera in a three-dimensional space.
From that, the camera pose (position and orientation) in 3D space is determined. These values are then used in the computer graphics calculations to render virtual objects. Finally, the rendered graphics are merged with the video frame and displayed to the user:
iOS and Android phones typically ...