Contouring by Indirect Method

Contouring is the process of representing the topography of a region on a map by means of contour lines. The indirect method of contouring involves the following steps:

1. Collecting data: The surveyor collects data on the elevation of various points on the terrain.

2. Plotting the data: The surveyor plots the data on a graph paper.

3. Interpolating the contour: The surveyor then interpolates the contour lines on the map.

Interpolation of Contour Lines

Interpolation is the process of estimating the value of a function for an intermediate value of the independent variable. In the indirect method of contouring, the surveyor has to interpolate the contour lines on the map. The best method of interpolation of the contour is by arithmetical calculation.

Arithmetical Calculation

Arithmetical calculation involves the following steps:

1. Calculate the difference in elevation between two adjacent contour lines.

2. Divide the difference in elevation by the distance between the two contour lines.

3. Multiply the quotient obtained in step 2 by the distance between the point being contoured and the lower contour line.

4. Add the product obtained in step 3 to the elevation of the lower contour line.

5. Repeat steps 2 to 4 for all the contour lines.

Advantages of Arithmetical Calculation

Arithmetical calculation has the following advantages:

1. It is a precise method of contouring.

2. It is easy to perform.

3. It can be done without the use of complicated mathematical formulas.

Conclusion

In conclusion, the best method of interpolation of the contour in the indirect method of contouring is by arithmetical calculation. It is a precise and easy method that can be done without the use of complicated mathematical formulas.