UAV photogrammetry in the post-earthquake scenario: case studies in L'Aquila

Figures & data

Figure 1. Image space and object space relationship.

Figure 2. Ground sample distance.

Figure 3. Geometry of oblique images.

Table 1. L'Aquila earthquake damages.

	Private buildings	Public buildings	Cultural Heritage
Safe	52%	53.6%	24.1%
Partially or temporary unsafe	15.9%	25.2%	22.2%
Totally unsafe	32.1%	21.2%	53.7%
Number of investigated buildings	71,302	2219	1800

Figure 4. Case studies: (a) Palazzo Square, (b) Collemaggio Basilica, (c) Fontecchio.

Figure 5. (a) Micro-octocopter, (b) Mini-quadcopter, (c) Mini-hexacopter.

Table 2. Case studies: survey characteristics.

Case study			Piazza Palazzo	Collemaggio Basilica	Fontecchio
Typology of construction			Historical square	Heritage Building	Roman built-up area
Type of UAV			Micro UAV	Mini-UAV	Mini-UAV
			Octocopter	Quadricopter	Hexacopter
Optical sensor	Camera		Canon-EOS 550D	Canon S100	GoPro Hero 3+
	Resolution		18 MP	12 MP	12 MP
	Focal length		18 mm	5.2 mm	2.77 mm
	Sensor dimensions	Width	22.3 mm	7.6 mm	6.2 mm
		Height	14.9 mm	5.7 mm	4.6 mm
	Pixel dimension		4.3 μm	1.9 μm	1.5 μm
	Weight		530 g	192 g	74 g
FOV direction			UAV: Nadir	UAV: θ = 16.5°	UAV: Nadir
				Terrestrial: perpendicular
GSD			2 cm	4 mm–1 cm	1 cm
Flight altitude/distance			80 m	10–30 m	30 m
Overlapping of photograms	Longitudinal		80%	90%	80%
	Side lap		80%	90%	70%
Number of photograms			15	291	48
GCP	Instrument		NRTK	Total station	NRTK
	Number		13	60	4

Figure 6. (a) Flight planning, (b) GCP network.

Figure 7. Palazzo square: GCPs and CPs combinations.

Figure 8. Collemaggio Basilica: waypoints distribution.

Figure 9. Collemaggio Basilica: GCPs and CPs combination.

Figure 10. Fontecchio built-up area overview.

Figure 11. (a) Approximate volume of built-up area. (b) Waypoints distribution.

Figure 12. Fontecchio: GCPs and CP distributions.

Figure 13. 3D model: (a) Palazzo square, (b) Collemaggio Basilica, (c) Fontecchio.

Table 3. Results of bundle adjustment.

			Number	Residuals (cm)
Palazzo Square	Case 1	GCP	4	4
		CP	15	6
	Case 2	GCP	6	5
		CP	13	6
	Case 3	GCP	10	5
		CP	9	7
Collemaggio Basilica	Case 1	GCP	9	4
		CP	51	6
	Case 2	GCP	11	3
		CP	49	4
	Case 3	GCP	22	3
		CP	38	5
Fontecchio	Case 1	GCP	3	2
		CP	1	6
	Case 2	GCP	3	2
		CP	1	6
	Case 3	GCP	3	3
		CP	1	6

Figure 14. Orthophotos: (a) Palazzo square, (b) Collemaggio Basilica, (c) Fontecchio.

Figure 15. (a) DSM Palazzo square, (b) Depth scalar field Collemaggio Basilica, (c) DSM Fontecchio.