Scales
- The area that is surveyed is vast and, therefore, plans are made to some scale.
- Is the fixed ratio that every distance on the plan bears corresponding distance on the ground.
a) Representative Fraction
- Refers to the ratio on the drawing to the corresponding actual length of the object on the ground.
- F = Distance of the object on drawing/Corresponding actual distance of object on ground.
- For example: If a scale is 1 cm = 10m, then RF= 1/(10×100)= 1/1000 or 1:1000.
- If a scale is 1 cm = 100m, then RF= 1/(100×100)= 1/10000 or 1:10000.
- If a scale is 1 cm = 1000m or 1 km , then RF= 1/(1x1000x100)= 1/100000 or 1:100000.
b) Graphical Representation of Scale
- Has advantage that if the paper shrinks, the scale will also shrink accordingly and the distance will not be disturbed.