This lecture covers the fundamentals of geomatics, focusing on GPS technology and geodesy. The instructor discusses GPS measurements, including pseudo-distances and sources of errors such as ionosphere disturbances and multipath effects. The lecture also delves into the science of geodesy, explaining the challenges of defining a coordinate system on a dynamic and vast Earth. The conversion of latitude and longitude to Cartesian coordinates is explored, emphasizing the importance of understanding different coordinate systems for engineering applications.