Systems, Methods, and Graphical User Interfaces for Annotating, Measuring, and Modeling Environments

A computer system displays an annotation placement user interface that includes a representation of a field of view of one or more cameras that is updated over time based on changes in the field of view, a placement user interface element indicating a virtual annotation placement location. If the placement user interface element is over a representation of a physical feature in the physical environment that can be measured, the appearance of the placement user interface element changes in accordance with one or more aspects of the representation of the physical feature, and, in response to an input to perform one or more measurements of the physical feature: if the physical feature is a first type of feature, measurements of a first measurement type are made; and, if a second, different type of physical feature, measurements of a second, different measurement type are made.