Final answer:
To model a landscape covered by thick rainforest, Aerial LiDAR is the most suitable technique as it can penetrate vegetation from the air and quickly create detailed 3D models of the surface.
Step-by-step explanation:
To build a model of a landscape surface obscured by thick rainforest as an archaeologist, the most effective survey technique would be aerial LiDAR (Light Detection and Ranging). The LiDAR technology employs light in the form of a pulsed laser to measure variable distances to the Earth. This method is capable of penetrating the thick canopy of a rainforest and providing high-resolution models of the ground surface underneath, which is essential for detecting and documenting archaeological features.
Aerial LiDAR is particularly suited to this task as it can cover large areas quickly and produce data that allows for the creation of detailed three-dimensional representations of the landscape. It's more effective than Ground Penetrating Radar (GPR) or ground-based LiDAR for this purpose, as it can be deployed over dense vegetation from the air, whereas GPR requires contact with the ground and ground-based LiDAR would be significantly obstructed by the rainforest. Magnetometry is also of limited use here, as it measures variations in the Earth's magnetic field that are better suited for detecting ferrous items rather than creating landscape models.