1. In a digital medium environment, a method implemented by a computing device, the method comprising: receiving, by the computing device, a digital image, a three-dimensional model of a substrate, and digital content; applying, by the computing device, the digital image to the three-dimensional model of the substrate such that the digital image, as applied to the substrate, is viewable from a plurality of viewing directions based on an input from a sensor indicating an orientation in three-dimensional space; configuring, by the computing device, a material property of the three-dimensional model that includes the applied digital image to include the digital content as viewable at a particular viewing direction of the plurality of viewing directions; and outputting, by the computing device, the configured three-dimensional model to render the digital content as part of the digital image responsive to detection of the particular viewing direction by the sensor, such that the digital content is viewable at the particular viewing direction based on the material property of the substrate and is not viewable at another viewing direction of the plurality of viewing directions.