Page 5 - DGPS

Ground control points should be well-identifiable on image as well as ground
depends on image overlap.

Sharp intersections / corners of features should be selected for plani-
metric control.(e.g.sharp corner of road/track/field bund junctions should
be selected instead of centre of road intersection.)

Well identifiable points on flat surface and preferably at ground level
should be selected as Vertical Control. (Features above ground level
where small errors in GCP measurements can lead to substantial errors
in height, such as parapet walls, boundary walls, bund junctions, distance
stones etc should not be used as height points.)

The points which are to act as PH (Planimetric as well as height) control
should be so selected that they are suitable for planimetric as well as
height measurement. If unavoidable, separate Plan and Height control
may be provided at nearby locations.

GDOPs should not exceed 2 in any case. Normally this condition is
achieved when 5 (five) or more satellites above 20° (in some cases
above 15°) of altitude are available. GPS observation schedule should
be prepared by proper Mission Planning accordingly.

MRSAC,Nagpur ©®
MRSAC,Nagpur ©®