Terrain Matching Localization for Underwater Vehicle Based on Gradient Fitting

Table 4

Matching error comparison of three methods.

	Region	1	2	3	4	5	6	7
Fluctuation	σx	0.0874	0.1671	0.1010	0.1324	0.1886	0.1289	0.2354
		0.0773	0.1339	0.0950	0.1160	0.1457	0.1312	0.1643
Number of matching points	All	2025	2025	2025	2025	2025	2025	2025
	Uniform	1444	1444	1521	1444	1444	1521	1444
	Grad-fit	1385	1435	1450	1376	1389	1452	1428
(m)	All	2.8293	0.6474	1.2387	1.2078	0.1680	2.1053	0.2680
	Uniform	6.4865	2.0072	3.5304	2.2676	0.3186	6.8306	0.5573
	Grad-fit	2.6418	0.5448	1.1272	1.0042	0.1106	1.9543	0.2153