Digital cartographic system for geographical information processing

• US 5,544,052 A
• Filed: 02/28/1995
• Issued: 08/06/1996
• Est. Priority Date: 04/19/1991
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Nomoto, Yasuei, Fujita, Takehiro, Kakumoto, Shigeru
• Primary Examiner(s): McElheny, Jr., Donald E.
• Application Number:
  US08/396,328
• Time in Patent Office: 525 Days
• Field of Search: 364/420, 364/423, 364/443
• US Class Current: 702/5
• CPC Class Codes: G06T 17/05 Geographic models
• CPC Class Codes: G06T 3/12 Panospheric to cylindrical image transformations

Abstract

In a digital cartographic system for processing geographic information, a map projection of a map is converted. The map projection transformation is carried out with a coordinate value in which longitude and latitude are set to a center by way of a linear interpolation so as to simplify a calculation required for transforming the map projection, and also not depending upon a map projection to be converted. Also, after the transformation process operation, a reference line such as longitude/latitude and an equiangular line is superposition-displayed/overlapping-displayed in order to assist an analysis, in response to a demand. In accordance with the present invention, a map can be shown with correctness of a distance and correctness of azimuth by performing various sorts of map-projection transformation, the digital cartographic system can support an intuitive idea of a user, and also can improve an information representation function of this digital cartographic system.

Claims

1. A digital cartographic system for processing geographic information, comprising:

means for storing at least first graphic data obtained by a first map projection in which said graphic data is divided into management region units based on a longitude and latitude coordinate system;

a first table for storing at least values of coordinates of vertexes of each management region unit according to said first map projection and longitude/latitude coordinate values of the vertexes of each of said management region units;

a second table for storing management information concerning said first map projection and various map projections including a second map projection;

input means for selecting said second map projection to be transformed from said various map projections, and for designating a transformation region;

means for obtaining longitude/latitude coordinate values of vertexes of each management region unit included in said transformation region by reference to said first table, and for transforming obtained longitude/latitude coordinate values into coordinate values of the vertexes of said each management region unit according to said second map projection by assuming that values of said longitude and latitude coordinate system of two vertexes of four vertexes of said each management region unit are identical and by performing linear interpolation based on said management information concerning said second map projection stored in said second table;

means for obtaining coordinated transformation equations for each management region unit included in said transformation region from obtained longitude/latitude coordinate values of the vertexes in said each management region unit included said transformation region according to said first map projection that are stored in said first table and said coordinate values of the vertexes of said each management region unit according to said second map projection, and transforming said first graphic data into second graphic data according to said second map projection; and

means for displaying said second graphic data.

2. A digital cartographic system for processing geographic information according to claim 1, wherein said first table, when one of said first and second map projections is a map projection according to a UTM coordinate system, stores coordinate values of vertexes of each management region unit in one zone among zones each having predetermined area in a longitudinal direction, and said first graphic data is transformed by using said coordinate values of vertexes of said each management region unit in one zone, for another transformation region.

3. A digital cartographic system for processing geographic information according to claim 2, wherein when one of said first and second map projections is a map projection according to a UTM coordinate system, and when said transformation region extends over two zones which are located adjacent to each other, said first graphic data is transformed by using said coordinate values of vertexes of said each management region unit in a zone which is obtained by shifting one of said zones by a predetermined angle in said longitudinal direction.

4. A digital cartographic system for processing geographic information according to claim 1, further comprising:

means for producing reference line data of reference lines such as said longitude and latitude coordinate system; and

means for outputting said reference line data to said means for displaying such that said reference line data including a plurality of reference lines are displayed so as to be overlapped, when said second graphic data is displayed.

5. A digital cartographic system for processing geographic information according to claim 1, further comprising:

means for designating a path by said input means;

means for sequentially generating base points for transformation along said path designated by a user; and

means for outputting results of the map projection transformation to said means for displaying.

9. A digital cartographic system for processing geographic information according to claim 1, further comprising:

means for producing reference line data of reference lines such as said longitude and latitude coordinate system; and

means for outputting said reference line data to said means for displaying such that said reference line data including a plurality of reference lines are displayed so as to be overlapped, when said second graphic data is displayed.

10. A digital cartographic system for processing geographic information according to claim 1, further comprising:

means for designating a path by said input means;

means for sequentially generating base points for transformation along said path designated by a user; and

means for outputting results of the map projection transformation to said means for displaying.

6. A digital cartographic system for processing geographic information comprising:

means for storing at least a first graphic data obtained by a first map projection in which said graphic data is divided into units of a region of interest based on a longitude and latitude coordinate system;

a first table for storing at least values of coordinates of vertexes of each unit of the region of interest according to said first map projection and longitude/latitude coordinate values of the vertexes of said each unit of the region of interest;

a second table for storing management information concerning said first map projection and various map projections including a second map projection;

input means for selecting said second map projection to be transformed from said various map projections, and for designating a transformation region;

means for obtaining longitude/latitude coordinate values of vertexes of each unit of the region of interest included in said transformation region by reference to said first table, and transforming obtained longitude/latitude coordinate values into coordinate values of the vertexes of said each unit of the region of interest according to said second map projection, by assuming that values of said longitude and latitude coordinate system of two vertexes of four vertexes are identical, and by performing linear interpolation based on said management information concerning said second map projection;

means for obtaining coordinated transformation equations for said each unit of the region of interest included in said transformation region from said coordinate values of the vertexes in said each unit of the region of interest including said transformation region according to said first map projection that are stored in said first table and said coordinate values of the vertexes of said each unit of the region of interest according to said second map projection, and for transforming said first graphic data into a second graphic data according to said second map projection; and

means for displaying said second graphic data.

7. A digital cartographic system for processing geographic information according to claim 6, wherein said first table, when one of said first and second map projections is a map projection according to a UTM coordinate system, stores coordinate values of vertexes of each unit of the region of interest in one zone among zones each having a predetermined area in a longitudinal direction, and said first graphic data is transformed by using said coordinate values of vertexes of each unit of the region of interest in one zone, for another transformation region.

8. A digital cartographic system for processing geographic information, comprising:

means for storing at least first graphic data obtained by a first map projection in which said graphic data is divided into management region units based on a longitude and latitude coordinate system;

a first table for storing at least values of coordinates of vertexes of each management region unit according to said first map projection and longitude/latitude coordinate values of the vertexes of each of said management region units;

a second table for storing management information concerning said first map projection and various map projections including a second map projection;

input means for selecting said second map projection to be transformed from said various map projections, and for designating a transformation region;

means for obtaining longitude/latitude coordinate values of vertexes of each management region unit included in said transformation region by reference to said first table, and for transforming obtained longitude/latitude coordinate values into coordinate values of the vertexes of said each management region unit according to said second map projection by assuming that values of said longitude and latitude coordinate system of two vertexes of four vertexes of said each management region unit are identical and by performing linear interpolation based on said management information concerning said second map projection stored in said second table;

means for obtaining coordinated transformation equations for each management region unit included in said transformation region from obtained longitude/latitude coordinate values of the vertexes in said each management region unit included said transformation region according to said first map projection that are stored in said first table and said coordinate values of the vertexes of said each management region unit according to said second map projection, and transforming said first graphic data into second graphic data according to said second map projection; and

means for displaying said second graphic data;

wherein said first table, when one of said first and second map projections is a map projection according to a UTM coordinate system, stores coordinate values of vertexes of each management region unit in one zone among zones each having predetermined area in a longitudinal direction, and said first graphic data is transformed by using said coordinate values of vertexes of said each management region unit in one zone, for another transformation region; and

wherein when one of said first and second map projections is a map projection according to a UTM coordinate system, and when said transformation region extends over two zones which are located adjacent to each other, said first graphic data is transformed by using said coordinate values of vertexes of said each management region unit in a zone which is obtained by shifting one of said zones by a predetermined angle in said longitudinal direction.