Product Manual

134
Miscellaneous
Determining Points A & B and Distance D
• Choose two points that can easily be spotted both on the
image file and in the field.
• Go the the field and survey these two points with your
surveying system. This immediately gives the coordinates
x1, y1 and x2, y2 of points A and B respectively.
• From these coordinates, you can deduce D:
D = | x2-x1 |
Determining the Coordinates (x0, y0) of Point O
• Print out the image file using a high-quality printer.
• Using a graduated ruler, measure successively the lengths
of D, dh and dv on the map printout.
• Assuming the obtained measurements are respectively D’,
dh’ and dv’, we have:
D / D’ = dh /dh’ = dv / dv’
This means the values of dv and dh can be determined as
follows (make sure you use the same distance unit for all
these distances):
dh = (D x dh’) / D’ and dv = (D x dv’) / D’
The (x0, y0) coordinates are then:
x0 = x1 - dh and y0 = y1 + dv
x0 and y0 are the values you have to enter in the X
Coordinate and Y Coordinate fields of the World File Editor
window.
A (x1, y1)
O (x0, y0)
B (x2, y2)
W
D
dv
dh