Instruction Manual

English

1. Real coordinates of points A (x1, y1) and B (x2, y2), and

horizontal distance (D) between points A and B. Points A

and B are arbitrary points well distributed horizontally on

the image file and easy to spot both on the image file

(map) and in the field.

2. Real coordinates of point O (x0, y0) located at the upper-

left corner of the image file.

3. Image width expressed in pixels.

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’

A (x1, y1)

O (x0, y0)

B (x2, y2)