Methods of obtaining i contours

Methods of obtaining i contoursPrepared by: Andre‐Paul C. Ampong 2

Trace‐contour contour methodPrepared by: Andre‐Paul C. Ampong 4

Coordinate methodPrepared by: Andre‐Paul C. Ampong 5

Coordinate methodPrepared by: Andre‐Paul C. Ampong 6

Coordinate methodPrepared by: Andre‐Paul C. Ampong 7

Controlling‐point method• Considered to be one with the most universalapplication• Important points– Points are selected at random or along selectedlines– Controlling points are the points on the earth’ssurface where changes in ground slope occurPrepared by: Andre‐Paul C. Ampong 8

Cross‐profile methodPrepared by: Andre‐Paul C. Ampong 10

Photogrammetric methodPrepared by: Andre‐Paul C. Ampong 11

Photogrammetric method• Advantages– Speed of compilation– High accuracy of the locations of planimetric features– Fithfl Faithful reproduction of the configuration of theground by continuously traced contour lines– Reduction in the amount of control surveying requiredto control the mapping– Freedom from interferences by adverse weather andinaccessible terrain– Photographic representation of the details of the areais obtainedPrepared by: Andre‐Paul C. Ampong 12

Photogrammetric method• Disadvantages– Difficulty of plotting in areas with heavy groundcover– High cost of mapping– Difficulty of locating positions of contour lines inflat terrain– Necessity for field editing and field completion– Expensive cost of photogrammetric equipment– The need to train equipment operators to usecomplicated photogrammetric equipmentPrepared by: Andre‐Paul C. Ampong 13

StereoscopyPrepared by: Andre‐Paul C. Ampong 14