Which data formats can be used as reference data in auto registration?

The use of metadata in map sheet margins as reference data in auto registration is significant because metadata serves as contextual information that can guide the alignment and integration of various spatial datasets. Metadata does not represent the actual spatial features but rather provides essential details such as the scale, spatial resolution, projection information, and other characteristics that are crucial for accurately registering data layers.

In terms of auto registration, using metadata allows for a more informed approach to aligning datasets based on their inherent qualities and intended uses. This is particularly important when trying to combine disparate datasets that may have originated from different sources or formats, thus ensuring that they are correctly aligned in terms of spatial reference and other related attributes.

While raster and vector data can indeed be employed as reference data in many GIS applications, the question specifically highlights what constitutes reference data in the context of auto registration. Metadata plays a pivotal role by offering guidelines that enhance the process of aligning geographic data, making it a foundational component in the registration workflow. Additionally, the option mentioning "multiple reference layers" does not address the specific handling of metadata within those layers, which is why using metadata is particularly critical.