Method of applying a spherical correction to map data for rendering direction-of-travel paths on a wireless communications device

• US 8,032,155 B2
• Filed: 01/24/2007
• Issued: 10/04/2011
• Est. Priority Date: 03/31/2006
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Klassen, Gerhard Dietrich, Yach, David
• Primary Examiner(s): Hu; Jinsong
• Assistant Examiner(s): Nealon; William
• Application Number:
  US11/626,605
• Publication Number:
  US 20070229546A1
• Time in Patent Office: 1,714 Days
• Field of Search: None
• US Class Current: 455/456.2
• 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: G01C 21/3673 Labelling using text of road map data items, e.g. road names, POI names
• CPC Class Codes: G06F 16/29 Geographical information databases
• CPC Class Codes: G06F 16/9577 Optimising the visualization of content, e.g. distillation of HTML documents
• CPC Class Codes: G06F 3/0481 based on specific properties of the displayed interaction object or a metaphor-based environment, e.g. interaction with desktop elements like windows or icons, or assisted by a cursor's changing behaviour or appearance
• CPC Class Codes: G06F 3/147 using display panels
• CPC Class Codes: G06F 40/103 Formatting, i.e. changing of presentation of documents automatic justification G06F40/189; automatic line break hyphenation G06F40/191
• CPC Class Codes: G06T 11/60 Editing figures and text; Combining figures or text
• CPC Class Codes: G06T 15/503 Blending, e.g. for anti-aliasing
• CPC Class Codes: G06T 17/05 Geographic models
• CPC Class Codes: G06T 19/00 Manipulating 3D models or images for computer graphics
• CPC Class Codes: G06T 2219/004 Annotating, labelling
• CPC Class Codes: G08G 1/096805 where the transmitted instructions are used to compute a route
• CPC Class Codes: G08G 1/0969 having a display in the form of a map
• CPC Class Codes: G09B 29/10 Map spot or coordinate position indicators; Map reading aids optical projection apparatus per se G03B
• CPC Class Codes: G09B 29/106 using electronic means
• CPC Class Codes: G09G 2340/0492 Change of orientation of the displayed image, e.g. upside-down, mirrored
• CPC Class Codes: G09G 2340/10 Mixing of images, i.e. displayed pixel being the result of an operation, e.g. adding, on the corresponding input pixels
• CPC Class Codes: G09G 2340/145 related to small screens
• CPC Class Codes: G09G 5/377 for mixing or overlaying two or more graphic patterns G09G5/02, G09G5/397 take precedence

Abstract

Displaying a map on a wireless communications device includes steps of obtaining map data for rendering the map to be displayed on the wireless communications device, determining a rotation that, when applied to the map, will orient a selected path in a selected direction, such as a current direction of travel, generating a corrected rotation by applying a spherical correction factor, e.g. based on a current location, and rendering the map on a display of the wireless communications device by applying the corrected rotation. The spherical correction factor corrects for map distortions that occur at high latitudes for paths that are neither purely north-south or east-west. When such a path is rotated to face upward to show direction of travel, the path needs to be straightened by applying the spherical correction factor.

Claims

1. A method of displaying a map on a wireless communications device, the method comprising:

obtaining map data for rendering the map to be displayed on the wireless communications device;

identifying a path representing a current direction of travel of the wireless communications device;

determining a selected direction for rotating the map;

determining a rotation angle that, when applied to the map data, will rotate the map and orient the path representing the current direction of travel in the selected direction;

generating a corrected rotation by applying a single spherical correction factor to all vertices of the map data, the spherical correction factor being based on only the rotation angle and a latitude of a current position of the wireless communications device; and

rendering a rotated map on a display of the wireless communications device.

2. The method as claimed in claim 1 wherein the spherical correction factor is equal to arctangent (tangent(the rotation angle)/cosine(the latitude)).

3. The method as claimed in claim 1 wherein the path representing the current direction of travel is oriented vertically upward on the display of the device.

4. The method as claimed in claim 1 wherein generating the corrected rotation comprises calculating the spherical correction factor based on the latitude of the current position of the wireless communications device as determined using a Global Positioning System (GPS) receiver.

5. A computer-readable medium comprising code recorded on the computer-readable medium that, when loaded into memory and executed on a processor of a wireless communications device, causes the device to:

obtain map data for rendering the map to be displayed on the wireless communications device;

identify a path representing a current direction of travel of the wireless communications device;

determine a selected direction for rotating the map;

determine a rotation angle that, when applied to the map data, will rotate the map and orient the path representing the current direction of travel in the selected direction;

generate a corrected rotation by applying a single spherical correction factor to all vertices of the map data, the spherical correction factor being based on only the rotation angle and a latitude of a current position of the wireless communications device; and

render a rotated map on a display of the wireless communications device.

6. The computer-readable medium as claimed in claim 5 wherein the spherical correction factor is equal to arctangent(tangent(the rotation angle)/cosine(the latitude)).

7. The computer-readable medium as claimed in claim 5 wherein the path representing the current direction of travel is oriented vertically upward on the display of the device.

8. The computer-readable medium as claimed in claim 5 wherein generating the corrected rotation comprises calculating the spherical correction factor based on the latitude of the current position of the wireless communications device as determined using a Global Positioning System (GPS) receiver.

9. A wireless communications device for displaying a map the wireless communications device comprising:

an input device to cause the wireless communications device to obtain map data for rendering the map to be displayed on the device;

a processor for determining a path representing a current direction of travel of the wireless communications device, a selected direction and a rotation angle that, when applied to the map data, will rotate the map and orient the selected path of the map in the selected direction and for generating a corrected rotation by applying a single spherical correction factor to all vertices of the map data, the spherical correction factor being based on only the rotation angle and a latitude of a current position of the wireless communications device; and

a display for displaying a rotated map rendered by applying the corrected rotation to the map data.

10. The wireless communications device as claimed in claim 9 wherein the spherical correction factor is equal to arctangent(tangent(the rotation angle)/cosine(the latitude)).

11. The wireless communications device as claimed in claim 9 wherein the path representing the current direction of travel is oriented vertically upward on the display of the device.

12. The wireless communications device as claimed in claim 9 wherein the processor generates the corrected rotation by calculating the spherical correction factor based on the latitude of the current position of the wireless communications device as determined using a Global Positioning System (GPS) receiver.