What coordinate system is typically used to project data onto a 3D model?

The correct choice is the Projected Coordinate System (PCS). When projecting data onto a 3D model, a projected coordinate system is essential because it represents the Earth's curved surface in a two-dimensional plane. A PCS is designed to minimize distortions in area, shape, distance, or direction, allowing for more accurate representations of spatial data when rendered in a 3D format.

In contrast, a Geographic Coordinate System (GCS) provides latitude and longitude values that represent locations on the Earth's surface but does not account for the curvature of the Earth when projecting onto a flat surface. This makes it less suitable for 3D modeling, which requires flattened, planar data representations for accurate visualization.

The Universal Transverse Mercator (UTM) is itself a specific type of projected coordinate system, but just referencing UTM doesn't encompass the broader category of projected systems which are used in 3D modeling. Computer-Aided Design (CAD) is primarily a software tool used for drafting and design, rather than a coordinate system, and while CAD systems may utilize various coordinate systems, they are not inherently designed for geographic modeling. Therefore, the PCS is the most appropriate choice for the context of projecting data onto a 3D model.