The present invention generally relates to contouring in surveying. More particularly invention relates to a methodology of condouring for grid condour survey.

BACKGROUND OF THE INVENTION
Contouring in surveying is the determination of elevation of various points on the ground and fixing these points of same horizontal positions in the contour map. To exercise vertical control leveling work is carried out and simultaneously to exercise horizontal control chain survey or compass survey or plane table survey is to be carried out. If the theodolite is used, both horizontal and vertical controls can be achieved from the same instrument. It also an Imaginary line on the ground surface joining the points of equal elevation is known as contour. In other words, Contour is a line in which the ground surface is intersected by a level surface obtained by joining points of equal elevation. This line on the map represents a contour and is called Contour line. A map showing Contour Lines is known as Contour Map.
Contour surveying is useful in civil engineering in the following areas:
1. In the proper and accurate location of engineering projects such as roads, canals, etc.
2. In determining the location of water supply, water distribution and to solve the problem of steam pollution.
3. In planning and designing of dams, reservoirs, aqueducts, transmission lines, etc.
4. In the selection of sites for new industrial plants.
5. To determine the indivisibility of stations.
6. To determine the profile of the country in any direction.
7. To estimate the quantity if cutting-filling of soil and the capacity of a reservoir.

There are two methods of Contouring.
1. Direct method
2. Indirect method

In direct method of contouring high degree of precision is required for large-scale maps with small contour interval. In the Direct Method of contouring, the reduced level of various selected points on a contour line is obtained and their positions are located. The contours are then drawn by joining these points. It is very accurate method but is very tedious and time consuming.
• BY LEVEL AND STAFF: - In this a series of points having the same staff readings and thus the same elevations are plotted and joined by a smooth curve.
• By hand level/Abney level: - In this method the instrument may stands over the bench mark and the staff man are moved to a point on the contour which has to be plotted.
Indirect method of contouring is suitable for undulated ground and hilly areas. In this the points are selected at random. The positions and elevations of which are not necessarily located on a contour line. Tracing contour is the process in which the position and reduced level of all such points is then determined. The contours are then drawn by interpolation method.
A method of squares is also called as co-ordinate method of locating contours. The entire area is divided into squares or rectangles forming a grid. The elevations of corners are determined and the required contours are interpolated. This method is very suitable for a small open area where contours are required at a loss vertical interval. This is also suitable for large-scale mapping.
In method of cross-sections a transit traverse is run. This method is suitable for road, railway and canal survey i.e., for route surveys.
Tacheometric method is practically suitable for hilly areas and all places where plane table surveying is impractical. The elevations and distances are calculated from the observed data and contours are interpolated.
Plane table method, the distance and elevation of the staff point is reduced by trigonometric relations. The observer scales the computed distance along the plotted line to locate the point and writes the computed elevation in such a way that the plotted position of the point coincides with the decimal point of the elevation value.

OBJECT OF THE INVENTION
The object of the invention is to provide a contour map for Survey is carried out at the starting of any engineering project such as a road, a railway, a canal, a dam, a building etc.

SUMMARY
Contouring in surveying is the determination of elevation of various points on the ground and fixing these points of same horizontal positions in the contour map. To exercise vertical control levelling work is carried out and simultaneously to exercise horizontal control chain survey or compass survey or plane table survey is to be carried out. Main objective of conducting contour surveys is to identify any noticeable difference in elevation of the existing land. In land surveying a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes

BRIFE DISCRIPTION OF DRAWINGS
The novel features and characteristics of the disclosure are set forth in the description. The disclosure itself, however, as well as a preferred mode of use, further objectives, and advantages thereof, will best be understood by reference to the following description of an illustrative embodiment when read in conjunction with the accompanying drawings. One or more embodiments are now described, by way of example only, with reference to the accompanying drawings wherein like reference numerals represent like elements and in which:
Figure 1 shows a direct method of contouring, where reduced level of various selected point on contour line obtained and positioned and contour is drawn by joining these points.
Figure 2 (a-d) shows different indirect methods of contouring such as (a) a method of squares, where entire area is divided into squares and rectangle forming grid, (b) method of cross-section that is suitable for route survey, (c) tacheometric method that is suitable for hilly area and place table surveying, (d) plane table method.
Figure 3 shows contour line on a two-dimensional paper.
Figure 4(a-c) where (a) shows closed contour loop of hill and pond, (b) shows ridgeline and valleyline intersect contour at right angle, (c) shows intersection between two contours of overhanging cliff and vertical cliff.
Figure 5 (a) shows survey football ground of IFTM University, (b) illustrate grid formation of the football ground for survey.
Figure 6 (a- p) shows the various steps involved in the methodology for contouring.
Figure 7 show a table which gives data and analysis.

DESCRIPTION
For promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as would normally occur to those skilled in the art are to be construed as being within the scope of the present invention.
It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.
The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or method. Similarly, one or more sub-systems or elements or structures or components preceded by "comprises... a" does not, without more constraints, preclude the existence of other, sub-systems, elements, structures, components, additional sub-systems, additional elements, additional structures, or additional components. Appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but not necessarily do, all refer to the same embodiment.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention belongs. The system, methods, and examples provided herein are only illustrative and not intended to be limiting.
Embodiments of the present invention will be described below in detail with reference to the accompanying figures.
Our main purpose for this survey is to be familiar with field environment and to get practical knowledge of surveying and use of its instruments in field. Also, in 4th semester subject like Surveying requires knowledge about how different instruments are used in the field. The main purpose of preparation of contour is drawing of sections, determination of inter-visibility between two points, tracing of contour gradients, location of route, measurement of drainage area and calculation of reservoir capacity. A contour survey is a line that connects points of equal elevation. Contour survey is usually carried out in order to have an accurate record of the existing conditions of a portion of land that is about to undergo some type of construction activity.
A Contour line may be defined as an imaginary line passing through the points of equal devotion. A contour line may also be defined as the intersection of a level surface with the surface of the earth. When the contours are drawn underwater, they are termed as Submarine Contours, Fathoms or Bathymetric Curves. This is the best method of representation of features such as hills, depressions, underwater etc. on a two-dimensional paper.
Characteristics of contour surveying is given below: -
1. In contour surveying, all points in a contour line have the same elevation.
2. Contour lines are far away from each other in a flat region and close to each other in the mountainous region.
3. Uniform slope is indicated by uniformed spaced contour line from each other and flat ground is indicated as a straight line, uniformed space and parallel to each other.
4. A series of contour line which is closed to each other indicated a hill and the higher value inside.
5. A series of closed contour lines are indicating depression if the higher value is outside.
6. Contour lines are right angle in the valley or ridge portion. If the higher value is inside it indicates ‘Ridge’ or if a higher value is outside the bend it denotes ‘Valley’.
7. Contour lines can’t end anywhere but close on them or outside the map limit.
8. Contour lines are not cross to each other whether there is an overhanging cliff.
9. Contour lines never run into one another unless there is a vertical cliff.
10. Depression between summits is called a saddle. Four sets of contours are represented here. It represents the junction of two ridges or a dip in a ridge. The line which passes through saddles is called the watershed line.
The constant vertical distance between any two consecutive contours is called the contour interval.
We should use a constant contour interval through a map. The variable contour interval gives a false impression of the relative steepness of the surface in different parts of the map.
The horizontal distance between the two adjacent contours is called horizontal equivalent. It depends on the slope of the ground.
• For projects such as Highways & Railways = 2.0 m
• For Earth Works, Building Sites, Dams, City Survey = 0.5 m
• Geological Surveys = 6 – 15 m

The contour depends upon the following factors: -
• The scale of the map: - The contour interval normally varies inversely to the scale of the map i.e., if the scale of map is large, the contour interval is considered to be small and vice versa.
• Purpose of the map: - For every important and detailed design, contour interval should be kept small.
• Nature of the ground: - For flat ground, a small contour interval is chosen whereas, for undulating and broken ground, greater contour interval is adopted.
• Time and cost: - If the contour interval is small, greater time and funds will be required in the field survey, in reduction and in plotting the map. If the time and funds available are limited, the contour interval may be kept large.
• Slope: - Contour interval is directly proportional to slope. Contour interval for country is generally small, e.g., 0.25m, 0.5m, 0.75m, etc. contour interval in hilly areas is generally greater, e.g. 5m, 10m, 15m, etc.
Following are the characteristics of the contours: -
• If contours are parallel and spacing between them is also constant then it shows a uniform slope.
• Closely spaced contour represents a steep slope and distant contours represent generally mild slope.
• A closed contour (loop) represents either a hill or a pond. For a hill, readings increase toward the centre and for a pond, it decreases towards the centre.
• Ridgeline/valley line intersect contour at a right angle. (Line joining topmost point of a hill is called ridgeline and the line joining bottom-most points of a valley is called valley line.)
• Two contours of different elevation neither touch nor cross each other. (Exception: Vertical cliff & overhanging cliff)
Instruments used in contour survey: -
1. Auto level
2. Level staff
3. Tripod stand
4. Tape
5. Ranging rod
6. Cross staff

Procedure: -
1. First of all, picked up a ground of 100m X 100m.
2. Divide the whole ground in 10m X 10m square boxes.
3. Thus, we get 121 points for leveling.
Give a proper name to every points
4. Setup the auto level in the ground.
5. It is remembered that the level is then set up in such a position so that the maximum number of points can be commanded from the instrument station.
6. Hold the staff vertically on the first point A1 and take a reading. This reading will be the back sight, because it is the first staff reading after setting the instrument.
7. Now move to the next point A2, and hold the staff vertically on the point and this reading will be the intermediate sight.
8. Similarly move the next points, and filled their readings in the field book.
9. Repeat this process until you can command the points of field.
10. When it is difficult to take readings of more points.
11. Picked up a reading of a point, and this reading will be foresight.
12. Now change the position of instrument.
13. Fixed up the instrument on another point.
14. Fixed up the instrument on another point.
15. Now take the reading of the last point again from the instrument, now this reading is the back sight for this point.
16. So, we will get two reading on a single point and this is termed as point of changing of station.
17. Now again repeat the whole process.
18. And get the readings of all point.
19. Suppose the R.L. of A1 is 100m.
20. The height of instrument is determined by taking a back sight on the B.M. and adding it to the R.L. of bench mark.
21. For find the R.L of next level subtract the I.S of this level from HI.
22. Repeat this process for find the R.L of other points.

CLAIMS

We claim:

1. A method for contouring, comprising of:
a) a ground of 100m X 100 m;
b) whole ground is divided into 10m X 10m squares forming 121 boxes;
c) naming the boxes properly.

2. As claimed in claim 1, an auto level is setup in the ground.

3.As claimed in claim 1 and 2, we will get two reading on a single point and this is termed as point of changing of station.