Derivative-based selection of zones for banded map display

Patent metadata

Field	Value
Publication number	US-9430866-B2
Application number	US-201213566387-A
Country	US
Kind code	B2
Filing date	Aug 3, 2012
Priority date	Oct 12, 2011
Publication date	Aug 30, 2016
Grant date	Aug 30, 2016

Abstract

A graphics or image rendering system, such as a map image rendering system, determines a viewing window of a map surface to be displayed, wherein the viewing plane is at an angle of incidence with respect to the map surface. The method generally determines a depth boundary along the map surface where a height projection of a depth increment of a first unit of area is lower than a threshold height increment at a non-zero angle of incidence and at a single zoom level magnification. The method renders the first unit of area within the depth boundary and a second unit of area outside the depth boundary. The first unit of area is rendered at a first density of map data and the second unit of area is rendered at a second density of map data that is lower than the first density of map data.

First claim

What is claimed is:

1. A computer-implemented method for rendering a three-dimensional map on a display device comprising:
determining, using a computer device, a map surface plane and a viewing plane, wherein the viewing plane is at a non-zero angle of incidence with respect to the map surface plane;
determining, using the computer device, a first unit of area on the map surface plane, the first unit of area representing a map area viewed at a first zoom level through the viewing plane when the viewing plane is at a zero angle of incidence with respect to the map surface plane, wherein the first unit of area has two dimensions along the map surface plane;
calculating, using the computer device, a projection of a first dimension along the map surface plane of the first unit of area onto a first dimension along the viewing plane at the non-zero angle of incidence with respect to the map surface plane;
determining, using the computer device, if the projection is at a threshold of the viewing plane, wherein the threshold relates to a length on the viewing plane;
determining, using the computer device, a boundary on the viewing plane when the projection is determined to be at the threshold such that the location of the boundary changes as a function of a change in the non-zero angle of incidence; and
rendering on the viewing plane a projection of a first area of the map surface plane on one side of the boundary using a first density of map data and rendering a projection of a second area of the map surface plane on a second side of the boundary using a second density of map data lower than the first density of map data.

2. The computer-implemented method of claim 1 , wherein the first unit of area on the map surface plane corresponds with a pixel of the viewing plane when the map surface plane is rendered at the first zoom level and the viewing plane is at a zero angle of incidence with respect to the map surface plane; and
further including determining a second unit of area on the map surface plane that corresponds with a pixel of the viewing plane when the map surface plane is rendered at a second zoom level and the viewing plane is at a zero angle of incidence with respect to the map surface plane, and wherein the second unit of area represents a larger area of the map surface plane than the first unit of area.

3. The computer-implemented method of claim 2 , wherein the threshold is a height of one pixel of the viewing plane.

4. The computer-implemented method of claim 1 , wherein rendering the first area includes using map data of the first zoom level and rendering the second area includes using map data of a second zoom level, wherein the second zoom level is a lower zoom level having a lower corresponding magnification and a lower map density than the first zoom level.

5. The computer-implemented method of claim 1 , further including determining a second unit of area on the map surface plane, wherein the threshold is where the projection of the first dimension of the first unit of area on the viewing plane matches a projection of a second dimension of the second unit of area on the viewing plane.

6. The computer-implemented method of claim 1 , wherein determining the boundary is based on a ratio of the projection of the first dimension of the first unit of area on the viewing plane to a height of one pixel of the viewing plane.

7. The computer-implemented method of claim 1 , further including requesting, using the computer device, map data for rendering the projection of the first unit of area and the projection of the second unit of area.

8. The computer-implemented method of claim 7 , wherein requesting map data includes providing a resolution of the display device as part of the request.

9. The computer-implemented method of claim 7 , wherein requesting map data includes requesting the map data from a database stored on a different computer device.

10. A computer device comprising:
a communications network interface;
one or more processors;
one or more memories coupled to the one or more processors;
a display device coupled to the one or more processors;
wherein the one or more memories include computer executable instructions stored therein that, when executed by the one or more processors, cause the one or more processors to:
determine a map surface plane and a viewing plane, wherein the viewing plane is at a non-zero angle of incidence with respect to the map surface plane;
determine a first unit of area on the map surface plane, the first unit of area representing a map area viewed at a first zoom level through the viewing plane when the viewing plane is at a zero angle of incidence with respect to the map surface plane, wherein the first unit of area has two dimensions along the map surface plane;
calculate a projection of a first dimension along the map surface plane of the first unit of area onto a first dimension along the viewing plane at the non-zero angle of incidence with respect to the map surface plane;
determine if the projection is at a threshold of the viewing plane, wherein the threshold relates to a length on the viewing plane;
determine a boundary on the viewing plane when the projection is determined to be at the threshold such that the location of the boundary changes as a function of a change in the non-zero angle of incidence; and
render on the viewing plane a projection of a first area of the map surface plane on one side of the boundary using a first density of map data and rendering a projection of a second area of the map surface plane on a second side of the boundary using a second density of map data lower than the first density of map data.

11. The computer device of claim 10 , wherein the first unit of area on the map surface plane corresponds with a pixel of the viewing plane when the map surface plane is rendered at the first zoom level and the viewing plane is at a zero angle of incidence with respect to the map surface plane; and
further including determining a second unit of area on the map surface plane that corresponds with a pixel of the viewing plane when the map surface plane is rendered at a second zoom level and the viewing plane is at a zero angle of incidence with respect to the map surface plane, and wherein the second unit of area represents a larger area of the map surface plane than the first unit of area.

12. The computer device of claim 11 , wherein the threshold is a height of one pixel of the viewing plane.

13. The computer device of claim 10 , wherein the threshold is where the projection of the first dimension of the first unit of area on the viewing plane matches a projection of a second dimension of the second unit of area on the viewing plane.

14. The computer device of claim 10 , wherein the boundary is determined based on a ratio of the projection of the first dimension of the first unit of area on the viewing plane to a height of one pixel of the viewing plane.

15. The computer device of claim 10 , wherein rendering the projection of the first area of the map surface plane is based on map data of the first zoom level and rendering the projection of the second area of the map surface plane is based on map data of a second zoom level, wherein the second zoom level is a lower zoom level having a lower corresponding magnification and lower map density than the first zoom level.

16. The computer device of claim 15 , wherein the one or more memories include computer executable instructions stored therein that, when executed by the one or more processors, cause the one or more processors to request first zoom level map data fo

Assignees

• Cornell Brian
• Google Inc

Inventors

• Cornell Brian

Classifications

• G06T17/05

  Geographic models · CPC title

• G06T15/20 Primary

  Perspective computation · CPC title