Overlap between scans and height of scanned objects During a flight with TOPODRONE laser scanner, the ground surface is scanned with a certain width, called “scan”. The scan width is determined by the technical characteristics of the sensor, the operating altitude of the flight, and the terrain difference. To perform correct post-processing of data from TOPODRONE laser scanners it is necessary that neighboring scans have common overlap.  It is recommended to provide at least 30% lateral overlap to adjacent scans. Insufficient overlap between scans together with significant terrain differences can create an area without any data, which will significantly reduce the quality of output materials. When choosing a specific overlap value, parameters such as maximum laser beam length, scan angle (106 degrees on LiDAR for ALS) and height of the scanned object should be taken into account. To obtain optimal results when performing ALS with TOPODRONE laser scanners, it is recommended to use the following parameters when building a mission:: 1 2 3 4 5 LiDAR model, Maximum beam length Working height, m Scan width, m Distance between scan centers: % overlap, m Maximum height of scanned object: % overlap, m 30% 40% 50% 60% 30% 40% 50% 60% TOPODRONE HI-RES and 100 LITE 50 134 94 81 67 54 15 20 25 30 60 160 112 96 80 64 18 24 30 36 70* 140 98 84 70 56 21 28 35 42 TOPODRONE 200 ULTRA 100 267 187 161 134 107 30 40 50 60 110 292 205 176 146 117 33 44 55 66 120 320 224 192 160 128 36 48 60 72 130* 260 182 156 130 104 39 52 65 78 140* 280 196 168 140 112 42 56 70 84 Table 1. Dependence of the distance between scan centers on overlaps and working height. Schematic of the main parameters of two neighboring TOPODRONE scans on the side projection. The density of the received point cloud depends on such factors as: flight speed, flight altitude, surface reflectivity. As nominal initial values it is recommended to conduct flights at a drone flight speed of 6 m/s at a working altitude of 60 m for TOPODRONE 100 LITE, HI-RES and 120 m for TOPODRONE ULTRA with 40-60% overlap. Further changes of these parameters should be made taking into account the terrain, weather conditions and maximum height of scanned objects.