Method and system for scrolling a map display in a navigation application

• US 6,330,858 B1
• Filed: 11/09/2000
• Issued: 12/18/2001
• Est. Priority Date: 06/05/1998
• Status: Expired due to Term

• Current Assignee: HERE Global B.V. (Nokia Corporation)
• Original Assignee: Navigation Technologies Corp. (Nokia Corporation)
• Inventors: Rao, Srinivasa, Srivastava, Ashutosh, McDonough, William
• Primary Examiner(s): NGUYEN, TAN QUANG
• Application Number:
  US09/710,344
• Time in Patent Office: 404 Days
• Field of Search: 701/208, 701/209, 701/210, 701/211, 701/212, 360/990, 360/995
• US Class Current: 101/208
• CPC Class Codes: G01C 21/367 Details, e.g. road map scale, orientation, zooming, illumination, level of detail, scrolling of road map or positioning of current position marker
• CPC Class Codes: G09B 29/106 using electronic means
• CPC Class Codes: G09G 5/346 for systems having a bit-mapped display memory

Abstract

A system and method for implementing a smooth scrolling function in a map display tool used with a navigation system and a map database. The system includes a map processing layer in the map display tool having a multi-tasking abstraction layer and a synchronization object for allowing portability between different platforms. The method includes the steps of updating a display from a first graphics buffer while executing a look-ahead process in the background and filling a second graphics buffer with map information on a predicted future position.

Claims

1. In a navigation system having a display, a map database and a navigation application having a map display program, a method of scrolling a map on the display comprising the steps of:

providing a first graphics buffer holding map information regarding a geographic region containing a first location position, the map information in the first graphics buffer corresponding to data in a first map object;

providing a second graphics buffer for holding auxiliary map information regarding a geographic region for a predicted future location;

displaying a map area on the display, the map area comprising a portion of the map information in the first graphics buffer; and

executing a look-ahead process for rendering auxiliary map information to the second graphics buffer.

2. The method of claim 1, wherein the step of executing a look-ahead process comprises creating an auxiliary map object associated with the second graphics buffer.

3. The method of claim 2, wherein the step of executing a look-ahead process comprises rendering an auxiliary map in the second graphics buffer concurrently with scrolling the map area on the display, wherein the auxiliary map corresponds to data in the auxiliary map object, whereby the auxiliary map in the second graphics buffer represents the predicted future location.

4. The method of claim 1, wherein the step of executing a look-ahead process further comprises the step of obtaining a synchronization object from the navigation application prior to rendering the auxiliary map, wherein the synchronization object provides authorization for the map display program to begin rendering the auxiliary map.

5. The method of claim 1 further comprising the steps of:

scrolling the map area on the display until the map area reaches an edge of the map information in the first graphics buffer; and

when the edge of the map in formation in the first buffer is reached, copying the auxiliary map information from the second graphics buffer into the first graphics buffer.

6. The method of claim 1 wherein the step of providing a first graphics buffer holding map information regarding a geographic region containing a present position of a user comprises the steps of:

the map display program receiving a set of instructions from the navigation program, the set of instructions comprising a size and a location of the geographic region;

obtaining a plurality of data items from the map database corresponding to map information within the geographic region and map information adjacent to the geographic region; and

processing each of the obtained data items by;

constructing a shape of a map feature represented by the obtained data item;

converting the shape of the map feature to a desired coordinate system; and

rendering the map feature to the display to the first graphics buffer.

7. A method of rendering a map on a display in a navigation system having a display, the method comprising the steps of:

providing a map display program having a set of map processing functions and a map data structure;

retrieving a plurality of map data items for a predetermined geographical area from a map database stored on a computer readable medium, at least one of the map data items comprising feature information and name information corresponding to the feature information;

drawing the feature information to a first graphics buffer with the map display program;

storing the name information in the map data structure;

after drawing the feature information for all of the plurality of retrieved map data items, processing the name information in the map data structure and drawing the name information in the map data structure to the first graphics buffer; and

displaying a map on the display while drawing feature information and name information for a predicted future position to a second graphics buffer, the map comprising a first portion of the feature information and name information from the first graphics buffer.

8. The method of claim 7, wherein the step of displaying a map further comprises:

incrementally scrolling the map by displaying a second portion of the feature information and name information from the first graphics buffer on the display, wherein the second portion is shifted from the first portion by a predetermined amount in a predetermined direction.

9. A method of operation for a map display program comprising:

storing in a first graphics buffer in a computer memory data items representing geographic features for display on a computer screen, wherein the data items contained in the first graphics buffer correspond to a first area and the display on the computer screen corresponds to a second area, wherein the first area is larger than and encompasses the second area;

displaying on said computer screen said data items from said first graphic buffer that correspond to said second area;

as an area to be displayed on said computer screen shifts in a given direction, displaying on said computer screen said data items from said first graphic buffer that correspond to new positions of said second area;

storing in a second graphics buffer in the computer memory data items representing geographic features for display on the computer screen, wherein the data items contained in the second graphics buffer correspond to a third area that overlaps a portion of said first area in the given direction; and

copying said data items from said second graphic buffer into said first graphics buffer.

10. The method of claim 9 wherein the first graphics buffer and the second graphics buffer have a same size.

11. The method of claim 9 wherein the first graphics buffer and the second graphics buffer are sized to hold at least 25% more map data than corresponds to said second area.

12. The method of claim 9 further comprising:

using one thread for displaying on said computer screen; and

using another thread for storing data items in the second graphics buffer.

13. The method of claim 9 further comprising:

before storing data items in said second graphics buffer, verifying that any prior map processing steps have ceased.

14. The method of claim 9 wherein the step of storing data items in the second graphics buffer is performed concurrently with the step of displaying data items from the first graphic buffer on said computer screen.

15. The method of claim 9 further comprising:

while the area to be displayed on said computer screen shifts in the given direction, suppressing display of selected types of geographic features represented by data items in the first graphics buffer.

16. The method of claim 15 wherein the selected types of geographic features include rank 0 roads.

17. The method of claim 15 further comprising:

after the area to be displayed on said computer screen stops shifting, displaying the selected types of geographic features represented by data items in the first graphics buffer that had been suppressed.

18. The method of claim 9 further comprising:

after storing in the second graphics buffer the data items that correspond to the third area that overlaps the portion of said first area in the given direction and the area to be displayed on said computer screen shifts in a new direction different than the given direction, storing in the second graphics buffer new data items that represent geographic features for display on the computer screen, wherein the new data items correspond to a fourth area that overlaps said first area in the new direction.

19. The method of claim 9 wherein the step of copying said data items from said second graphic buffer into said first graphics buffer is performed once the area to be displayed on said computer screen reaches an edge of the first area.

20. The method of claim 9 further comprising:

prior to the step of copying data items from said second graphic buffer into said first graphics buffer, checking that the step of storing data items in the second graphics buffer is finished.