The precise multimode GNSS positioning for UAV and its application in large scale photogrammetry

Figures & data

Figure 1. Configuration of GNSS-supported AT system.

Figure 2. Trajectory of the GPS system solution.

Figure 3. Trajectory of the multimode GNSS system solution.

Table 1. Ratio of differential positioning between GPS and multimode GNSS system.

Constellation	SPP solution %	Float solution %	Fixed solution %
GPS	5.7	22.9	71.3
GNSS	1.0	0.8	98.2

Figure 4. Elevation angle of GPS satellites.

Figure 5. Elevation angle of GPS/BDS/GLONASS satellites.

Figure 6. Number of GPS satellites.

Table 2. Bundle adjustment accuracy comparison of different methods.

Experiment no	Adjustment method	Number of OPs		Max residuals of OPs (m)		RMS of OPs (m)		Max error of CPs (m)		RMS of CPs (m)
		XY	Z	XY	Z	XY	Z	XY	Z	XY	Z
1	Traditional method	65	65	0.313	0.348	0.157	0.081	0.342	0.819	0.171	0.179
2	Without GNSS	4	4	0.056	0.016	0.041	0.011	0.604	−18.093	0.242	11.630
	GPS	4	4	0.089	−0.079	0.069	0.054	0.687	1.749	0.260	0.437
	GNSS	4	4	0.116	0.035	0.104	0.025	0.360	−0.862	0.190	0.387
3	Without GNSS	10	10	0.257	−0.065	0.121	0.038	0.411	−2.792	0.187	1.442
	GPS	10	10	0.364	0.148	0.168	0.069	0.564	1.469	0.234	0.390
	GNSS	10	10	0.286	−0.138	0.156	0.060	0.406	−0.787	0.183	0.229
4	Without GNSS	19	19	0.311	−0.077	0.140	0.042	0.426	−0.913	0.181	0.229
	GPS	19	19	0.383	0.361	0.157	0.105	0.519	0.897	0.213	0.268
	GNSS	19	19	0.164	0.288	0.150	0.064	0.413	−0.690	0.183	0.196
5	Without GNSS	40	40	0.310	0.207	0.149	0.059	0.363	0.534	0.173	0.153
	GPS	40	40	0.353	0.329	0.160	0.099	0.432	0.819	0.193	0.237
	GNSS	40	40	0.306	0.259	0.159	0.073	0.355	0.586	0.177	0.149

Notes: OP and CP denote the orientation point and the check point, respectively. XY and Z denote the horizontal and vertical coordinates, respectively.