Table 1.

Deviation (in pixels) between points in the reference map and in the map resulting from the georeferencing operation.

Control point	Number of points employed for georeferencing images				Mean deviation
	7	10	15	20
1	0.00	1.00	1.00	1.41	0.85
2	2.24	2.24	2.24	2.24	2.24
3	2.00	1.00	1.41	2.00	1.60
4	3.00	3.16	3.16	3.00	3.08
5	4.00	3.00	3.00	3.00	3.25
6	0.00	1.00	1.00	1.00	0.75
7	1.00	1.41	1.41	1.00	1.21
8	1.41	0.00	1.41	1.41	1.06
9	7.00	7.00	7.00	7.00	7.00
10	7.07	6.00	6.08	5.10	6.06
11	3.61	3.61	3.16	3.16	3.38
12	2.83	2.24	1.41	1.41	1.97
13	4.12	3.16	3.16	2.24	3.17
14	3.61	4.12	3.16	3.16	3.51
15	2.24	2.83	3.61	3.61	3.07
16	2.00	2.00	2.00	2.24	2.06
17	3.61	3.61	3.61	4.24	3.76
18	7.28	8.06	7.07	7.00	7.35
19	2.00	2.00	2.24	2.24	2.12
20	4.12	4.00	4.00	4.00	4.03
Error standard deviation	3.76	3.67	3.54	3.47	3.61