Method of assisting detection of man-made structures in a digital elevation map (DEM)

• US 6,104,981 A
• Filed: 02/19/1998
• Issued: 08/15/2000
• Est. Priority Date: 02/20/1997
• Status: Expired due to Fees

• Current Assignee: Alcatel SA (Nokia Corporation)
• Original Assignee: Alcatel SA (Nokia Corporation)
• Inventors: Louis, Christian, Lechervy, Yves
• Primary Examiner(s): McElheny, Jr., Donald E.
• Application Number:
  US09/025,817
• Time in Patent Office: 908 Days
• Field of Search: 702/5, 382/113, 382/108, 382/260
• US Class Current: 702/5
• CPC Class Codes: G06F 18/00 Pattern recognition
• CPC Class Codes: G06T 17/05 Geographic models

Abstract

A method of detecting man-made structures in a digital representation of a terrain, wherein said representation is a digital elevation map, and wherein said method comprises the following steps:

computing isolines in said digital elevation map;

filtering said isolines on the basis of a size criterion;

computing extremum isolines from the isolines filtered during the preceding step; and

determining said regions of interest. The invention is applicable to any process involving supervision of a geographical site (e.g. planning cellular telecommunications networks).

Claims

1. A method of detecting regions of interest containing man-made structures in a terrain representation, wherein said terrain representation is a digital elevation map, and wherein said method comprises:

providing information representing the digital elevation map and information representing a size criterion;

using a computer to compute isolines in said provided digital elevation map;

filtering said computed isolines on the basis of the provided size criterion;

computing extremum isolines from the filtered isolines; and

isolating said regions of interest containing man-made structures from regions delimited by the computed extremum isolines.

2. A method according to claim 1, wherein, after computing said extremum isolines, said method includes:

inputting a threshold value;

computing a total length of ridge lines contained in each of said extremum isolines; and

filtering said extremum isolines as a function of a comparison between said computed total length of ridge lines and said inputted threshold value.

3. A method according to claim 1, wherein each region of interest is delimited in three dimensions:

by an isoline resulting from the computed extremum isolines;

by the horizontal plane containing said extremum isoline; and

by the horizontal plane containing the point of maximum height contained in said isoline.

4. A method according to claim 1, wherein computing the isolines is immediately followed by deleting the open isolines from said isolines.

5. A method according to claim 2, wherein each region of interest is delimited in three dimensions:

by an isoline resulting from the filtered extremum isolines;

by the horizontal plane containing said extremum isoline; and

by the horizontal plane containing the point of maximum height contained in said isoline.

6. A method of optimizing locations of base stations for cellular radiocommunications networks involving detecting regions of interest containing man-made structures in a terrain representation, wherein said terrain representation is a digital elevation map, and wherein said method comprises:

providing information representing the digital elevation map and information representing a size criterion;

using a computer to compute isolines in said provided digital elevation map;

filtering said computed isolines on the basis of the provided size criterion;

computing extremum isolines from the filtered isolines; and

isolating said regions of interest containing man-made structures from regions delimited by the computed extremum isolines.

7. A method according to claim 6, wherein, after computing said extremum isolines, said method includes:

inputting a threshold value;

computing a total length of ridge lines contained in each of said extremum isolines; and

filtering said extremum isolines as a function of a comparison between said computed total length of ridge lines and said inputted threshold value.

8. A method according to claim 6, wherein each region of interest is delimited in three dimensions:

by an isoline resulting from the computed extremum isolines;

by the horizontal plane containing said extremum isoline; and

by the horizontal plane containing the point of maximum height contained in said isoline.

9. A method according to claim 6, wherein said computing the isolines is immediately followed by deleting the open isolines from said isolines.

10. A method according to claim 7, wherein each region of interest is delimited in three dimensions:

by an isoline resulting from the filtered extremum isolines;

by the horizontal plane containing said extremum isoline; and

by the horizontal plane containing the point of maximum height contained in said isoline.