As the GNSS receiver is used to measure the camera position, not the ground topography, it is not necessary to measure or to keep constant the height of the camera above the ground. Indeed, as the distance (noted D) between the camera and the GNSS antenna is kept constant throughout all image acquisitions, this offset is directly subtracted from the position that is measured by the GNSS antenna (Equation (1)), providing accurate camera location. For this study, we used a Topcon ® HiPer V GNSS receiver. The GNSS base station is set up on an existing geodetic marker located near the car park at the north-east of the study site (see Figure 1b). The same GNSS base was used for both the RTK GNSS-assisted terrestrial SfM photogrammetric survey and validation surveys.

### Language ###
English

### Assessment ###
We can ask about the specific GNSS receiver model used in this study.

### Query ###
What model of Topcon GNSS receiver is the HiPer V?
What model of Topcon GNSS receiver is the HiPer V?