High Resolution 1:10,000 scale Mapping Strategy of Multi ... - NDMA

7. GCP Accuracy
(95%
confidence)
Horizontal
Vertical
Required on the
ground
Better than 30
cm
Better than 20
cm
Table 9.3: Comparison between satellite imagery, aerial photography and
Vehicle mounted ground survey
Automatically done
Better than 5 cm
Better than 5 cm
Based on experiences, optical images should have a ground sampling distance (GSD) of
0.05mm up to 0.1mm in the map scale corresponding to a map scale of 1: 20,000 up to 1:
10,000 for a GSD of 1m. GSD is the distance of the centre of neighborhood pixels
projected on the ground. Because of over or under-sampling, the GSD is not identical to the
projected size of a pixel, but for the user, the GSD appears as pixel size on the ground.
GSD Target map scale Comparisons
AT GSD 10 cm Aerial Satellite
1:500 0.05 m Not Good
1:1,000 0.05 m Not Good
AT GSD 20 cm 1:2,000 0.10 m Not Good
1:2,500 0.10 m Not Good
1:3,000 0.10 m Not Good
1:4,000 0.10 m Not Good
1:5,000 0.10 m Not Good
AT GSD 50 cm 1:8,000 0.25 m 2.5 m
1:9,000 0.25 m 2.5 m
Automatically done
Better than 5 cm
Better than 5 cm
8. 3D imaging Rough estimate Accurate Accurate
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