Extracting the Hilltop

The Brazilian environmental legislation defines, in article 2 of the 4771 law from September 15, 1965, the permanent preservation areas. The hilltop is one of these areas. The definition of a hilltop is given in the resolution number 4 from September 18, 1985. In this resolution, in article number 2, a mountain or hill is defined as a “terrain elevation where the peaks height is between 50 (fifty) and 300 (three hundred) meters from the mountain or hill base and hillside with declivity greater than 30% (around 17o) in the highest declivity line”. A hill “is defined from the ordinary to isolated elevations in the fields”. In article number 3, in the same resolution, ecological preservation areas are defined as “mountain and hill peaks in delimited areas starting at the 2/3 minimum height level from the base”.

The purpose of this tool is to help the user when defining preservation areas at hilltops as defined above. Using a regular elevation grid as a supporting tool, the user can select the mountain highest point and also the mountain minimum point (the mountain base). Starting from the maximum and minimum points defined, the system computes the height corresponding to two thirds of the difference and generates an contour line with this height value. The generated line is stored in the thematic Information Layer previously selected.

 
Extraction of Tops:

  • activate, in the "Control Panel", the Information Layer which has a regular elevation grid;
  • click on DTM - Peak Extraction... in the main menu;
  • click on Output IL...;
  • select the category and the Output Layer which has hilltop lines;
  • click on Maximum Point;
  • select, using the point cursor, the mountain maximum position;
  • click on Minimum Point;
  • select, using the point cursor, the mountain minimum position (base);
  • click on Generate Contour lines to generate the contour line corresponding to the selected mountain peak.

See also:
DTM products in the SPRING - What are they and how to execute them?
Editing numerical maps