A method is provided for markerless injection of content into an augmented reality scene by use of a mobile device. Through the mobile device, a camera feed of a scene is acquired, which includes a flat surface. A key frame of the flat surface is selected from the feed. After determining that the flat surface in the key frame meets a predetermined level of feature richness, digital content is injected by superimposing text, graphics, video content over at least a part of the key frame. The digital content can be viewed and interacted with by the user of the mobile device. In one embodiment, the digital content is an advertisement.