A bridge appears on a pair of overlapping vertical photographs. Determine the length and slope of the bridge from the following data and absolute parallax measurements. The known data includes:

Flying height above mean terrain height is H-h=1200m

Air Base is B= 750m

Camera focal length, for c = 152.5mm

Measured image coordinates (mm):

xa 37.2

ya 39.6

xb 34.3

yb 22.7

x'a -52.8

x'b -53.6

Hint from the lecturer In order to determine the length of the bridge, you need to initially compute the ground coordinates of the bridge utilizing the formulae specified in section 3.1.1 (b & c). You can then calculate the length and the slope using the height differences.

Transcribed Image Text:

From the similar triangles O₁ Pp'1 A' & O₁ Pp1 a'1 we get: ΧΑ = YA Χια C A similar analysis will give: V1a B PXA = (Η – h) .. as (H - h) = B C PXA *1a B c CPXA → XA = .eqn 3.1.1(c) *1α Β PXA ...eqn 3.1.1(b) From the similar triangles O₁ Pp'1 A' & O₁ Pp1 a'1 we get: ΧΑ = YA Χια C A similar analysis will give: V1a B PXA = (Η – h) .. as (H - h) = B C PXA *1a B c CPXA → XA = .eqn 3.1.1(c) *1α Β PXA ...eqn 3.1.1(b)