In one embodiment, a modular sensor assembly configured for mounting on a vehicle includes a first set of sensors and a second set of sensors. The modular sensor assembly includes a coordinate frame baseplate including a continuous surface, and sensor mounting elements coupled to the continuous surface for mounting the first set of sensors at a first height. The coordinate frame baseplate includes a sensor platform configured for mounting the second set of sensors at a second height. The first set of sensors and the second set of sensors are coupled to the coordinate frame baseplate so as to impart a common coordinate frame for the first set of sensors mounted at the first height and the second set of sensors mounted at the second height. The modular sensor assembly includes a bridging support structure coupled to the coordinate frame baseplate and capable of being mounted on a vehicle.