METHOD OF APPLYING A SPHERICAL CORRECTION TO MAP DATA FOR RENDERING DIRECTION-OF-TRAVEL PATHS ON A WIRELESS COMMUNICATIONS DEVICE

• US 20070229546A1
• Filed: 01/24/2007
• Published: 10/04/2007
• Est. Priority Date: 03/31/2006
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Research In Motion Limited (Blackberry Limited)
• Inventors: YACH, David, KLASSEN, Gerhard Dietrich
• Granted Patent: US 8,032,155 B2
• Time in Patent Office: Days
• US Class Current: 345/649
• 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 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 obtained map data, will orient a selected path of the map in a selected direction;

generating a corrected rotation by applying a spherical correction factor to the rotation; and

rendering a rotated map on a display of the wireless communications device by applying the corrected rotation to the obtained map data.

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

3. The method as claimed in claim 1 wherein the selected path is a current direction of travel of the device.

4. The method as claimed in claim 1 wherein the selected path is a current direction of travel of the device and wherein the selected path is oriented vertically upward on the display of the device.

5. The method as claimed in claim 1 wherein the step of generating the corrected rotation comprises a step of calculating a single spherical correction factor for applying to all of the vertices of the map to be rendered based on a latitude of a current position of the device.

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

7. A computer program product comprising code adapted to perform the steps of claim 1 when the computer program product is loaded into memory and executed on a processor of a wireless communications device.

8. The computer program product comprising code adapted to perform the steps of claim 2 when the computer program product is loaded into memory and executed on a processor of a wireless communications device.

9. The computer program product comprising code adapted to perform the steps of claim 3 when the computer program product is loaded into memory and executed on a processor of a wireless communications device.

10. The computer program product comprising code adapted to perform the steps of claim 4 when the computer program product is loaded into memory and executed on a processor of a wireless communications device.

11. The computer program product comprising code adapted to perform the steps of claim 5 when the computer program product is loaded into memory and executed on a processor of a wireless communications device.

12. The computer program product comprising code adapted to perform the steps of claim 6 when the computer program product is loaded into memory and executed on a processor of a wireless communications device.

13. A wireless communications device for enabling a user of the device to display a map on the device, the wireless device comprising:

an input device for enabling the user to cause the device to obtain map data for rendering the map to be displayed on the device;

a processor for determining a rotation that, when applied to the obtained map data, will orient a selected path of the map in a selected direction and for generating a corrected rotation by applying a spherical correction factor to the rotation; and

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

14. The wireless communications device as claimed in claim 13 wherein the spherical correction factor is equal to arctangent(tangent(rotation angle)/cosine(latitude)).

15. The wireless communications device as claimed in claim 13 wherein the selected path is a current direction of travel of the device.

16. The wireless communications device as claimed in claim 13 wherein the selected path is a current direction of travel of the device and wherein the selected path is oriented vertically upward on the display of the device.

17. The wireless communications device as claimed in claim 13 wherein the processor generates the corrected rotation by calculating a single spherical correction factor for applying to all of the vertices of the map to be rendered based on a latitude of a current position of device.

18. The wireless communications device as claimed in claim 13 wherein the processor generates the corrected rotation by calculating a spherical correction factor based on a latitude of a current position of the device as determined using a Global Positioning System (GPS) receiver.