Define region holding data points

By pressing the Define (Data to use) we activate the close polygon definition tool, which in turn works in three modes. In the first, and with the left button, it is possible to pick a previously created closed polygon, which will enclose the data points who define the DEM. Both the second and third modes are capable to select manually the vertex of the polygon, which might or not be existing data points. The procedure is simple: with the left button, you will pick one after the other the vertex, until you close the polygon by clicking the right button and thus enclosing the data points. In Fig. 61 you see an intermediate stage of the process. In any case, once closed, the selected points change for a moment its symbol, the area where the contour lines will be restricted to be is displayed as a dashed region (illustrated in Fig. 62), and finally a summary of the statistics of the enclosed points is presented similar to the one presented in Fig. 63. This region might be convex or not (in the illustration it is concave) and in any case the contour lines will be splitted in order to belong to the inner side of the area. Another consequence is that the face of the Define button changes to Redefine, stating that now there is enough information for building the DEM. You should notice that, while picking the vertex, EasyDEM looks among the existing data points those which are at a prescribed distance; such tolerance distance could be modified through File>>Preferences>>Specify Tolerance. The selection procedure uses all the visible points in the working area. In particular, if you have a Reference Surface, be carefull to hide it before selecting the data points.

Fig. 61 Fig. 62

Fig. 63