A Digital Terrain Model is made from a job done with 3D and 2D drawing elements having height (contour lines, 3D lines, etc.), or alternatively with field data represented by points. These points, conveniently "joined together", make up what is called a scatter plot. The points are represented by their X, Y, Z coordinates and usually by an ordinal number and an associated code. These data organized in lines and columns with defined separators form a point data file. This application also allows one to modify the scatter plot by means of a set of tools that are described in this section.
Estimation of Uncertainties
MDT version 8 enables us to store the uncertainty of the X, Y, Z coordinates of each point. These values can be assigned using the following methods:
· If the points have been surveyed using a GNSS receiver, depending on the format of the files, they may be included in the estimated horizontal and vertical positions. For example, if the data has been taken using the TcpGPS application, the uncertainties will be assigned automatically on importing the points.
· If the points have been surveyed using a Total Station and calculated using the MDT Surveying model, the uncertainties of each point are calculated based on the characteristics of the tool, which should be defined within the properties of the survey.
· Finally, the values of the uncertainties can be assigned by means of a ManualEntry using the Change Uncertainties command.
It should be considered that the confidence level for the estimation of uncertainties (95% by default) is established in the Surveying settings. See the Customization Manual for more details.
TcpMDT