After carrying out the land survey, the work consists of reporting the data on paper. This tedious work is now supported by topography software, however it is instructive to have carried out at least one manual report to assimilate the method.
We consider 2 points surveyed on the ground 'a' and 'b' with respective altitudes Alta and Altb. The distance between these 2 points is L. The objective is to draw a level curve by calculating the distance 'LaM'. The whole is represented by the diagram.
The distance LaM is given by the relation:
Application 1 : The figure below represents the survey of a pattern of points in order to draw the level curve +129.50m .
We identify the points that frame this curve: 17 and 19 are above, 18 , 20 and 24 are below. Points 31 and 23 are too far apart: they will not be taken into account. It remains to be determined by interpolation of the crossing points of the curve over the four segments 1718 , 17 - 20 , 19 - 20 and 19 - 24 ; these segment are chosen so as to be as short and as perpendicular as possible to the futuretopographic contour line; for example, the segment 17 - 24 is discarded .
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