Variations in volumetric erosion rates of bedrock cliffs on a small inaccessible coastal island determined using measurements by an unmanned aerial vehicle with structure-from-motion and terrestrial laser scanning

Progress in Earth and Planetary Science

Table 2 Properties of measurement data. Asterisk (*) indicates that, only for this case, the UAS point cloud was registered to the UAS point cloud of number 3 (Feb. 11, 2015) because of the lack of TLS data

	Number of surveys	1	2	3	4	5	6	7
	Data of measurement	Jun. 24, 2014	Oct. 31, 2014	Feb. 11, 2015	Jun. 18, 2015	Oct. 23, 2015	Feb. 23, 2016	Jun. 18, 2016
	Weather	Cloudy	Cloudy	Sunny	Sunny	Sunny	Sunny	sunny
	Period length (days)	–	129	103	126	120	131	116
TLS	Number of TLS scan position	1	–	10	6	4	6	8
	Internal registration errors (mm)	–	–	5.3	3.5	8.9	15.9	11.7
	Total number of TLS points measured	750,045	–	138,546,188	67,488,458	36,013,373	56,232,226	65,453,912
	Number of TLS points used	294,888	–	990,882	14,062,296	2,624,403	4,508,131	5,895,657
GNSS	Number of GCPs	4	–	7	6	3	6	5
	Horizontal errors in GCP (mm)	16.8	–	14.9	13.5	14.3	13.4	13.6
	Vertical errors in GCP (mm)	21.8	–	29.4	29.2	21.3	24.6	22.8
ICP	External registration errors (mm)	13.9	–	21.2	8.1	6.4	[BASE]	10.6
UAV	UAS registration errors (mm)	33.5	18.8*	39.7	24.6	30.1	25.1	30.2
	Total number of measured points used	18,319,013	10,926,651	63,738,045	46,470,682	18,468,025	24,070,025	16,751,012
	Number of points used	9,761,070	5,172,098	34,949,713	25,753,386	7,181,782	7,032,236	7,042,244