Rendering a text image following a line

• US 8,400,453 B2
• Filed: 06/30/2011
• Issued: 03/19/2013
• Est. Priority Date: 06/30/2011
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Cornell, Brian
• Primary Examiner(s): Crawford, Jacinta M
• Application Number:
  US13/174,283
• Publication Number:
  US 20130002678A1
• Time in Patent Office: 628 Days
• Field of Search: 345/467, 715/780
• US Class Current: 345/467
• CPC Class Codes: G06T 11/20 Drawing from basic elements, e.g. lines or circles
• CPC Class Codes: G06T 11/203 Drawing of straight lines or curves

Abstract

A graphics or image rendering system, such as a map image rendering system, receives image data from an image database in the form of vector data that defines various image objects, such as roads, geographical boundaries, etc., and textures defining text strings to be displayed on the image to provide, for example, labels for the image objects. The imaging rendering system renders the images such that the individual characters of the text strings are placed on the image following a multi-segmented or curved line. This rendering system enables text strings to be placed on a map image so that the text follows the center line of a curved or angled road or other image feature without knowing the specifics of the curvature of the line along which the text will be placed when creating the texture that stores the text string information. This feature provides enhanced visual properties within a map image as it allows, for example, road names to be placed anywhere inside a road following the curvature of the road, thus providing a pleasing visual effect within the map image.

Claims

1. A computer-implemented method for rendering an image on a display device, comprising:

determining, using a computer device, a line within the image along which to render a text string that is stored as a set of pixelated text characters within an image lookup table;

determining, using the computer device, a plurality of line segments associated with the line and a range associated with each line segment, wherein at least two sequential line segments of the plurality of line segments are at an angle with each other;

forming, using the computer device, a text box for each of the plurality of line segments, each of the text boxes being oriented to draw text in an upright position along an associated line segment, the text box having a horizontal component along the range of the line segment and a vertical component perpendicular to the range of the line segment;

selecting, using the computer device, one of the text boxes in which to render a text character of the text string, wherein the one of the text boxes is associated with one of the at least two sequential line segments that are at an angle with each other;

selecting, using the computer device, one of the text characters from the text string stored as a set of pixelated text characters within the image lookup table;

determining, using the computer device, if a center of the one of the text characters, when rendered in the one of the text boxes on the image, will be within the range of the line segment associated with the one of the text boxes; and

rendering, using the computer device, the one of the text characters on the display device using the one of the text boxes if a center of the one of the text characters when rendered in the one of the text boxes will be within the range of the line segment associated with the one of the text boxes; and

not rendering the one of the text characters on the display device using the one of the text boxes if a center of the one of the text characters when rendered in the one of the text boxes will not be within the range of the line segment associated with the one of the text boxes.

2. The computer implemented method of claim 1, further including selecting a different one of the plurality of text boxes that is associated with a second of the at least two line segments that are at an angle with each other as the one of the text boxes for use in rendering the one of the text characters on the display device if the center of the one of the text characters, when rendered in the one of the text boxes will not be within the range of the line segment associated with the one of the text boxes.

3. The computer-implemented method of claim 1, further including selecting each one of the text characters from the text string stored within the image lookup table in turn and, for each selected one of the text characters, performing the steps of;

determining, using the computer device, if the center of the selected one of the text characters, when rendered in the one of the text boxes, will be within the range of the line segment associated with the one of the text boxes,

rendering, using the computer device, the selected one of the text characters on the display device using the one of the text boxes if the center of the selected one of the text characters when rendered in the one of the text boxes will be within the range of the line segment associated with the one of the text boxes, and

selecting a different one of the plurality of text boxes that is associated with a second of the at least two line segments that are at an angle with each other as the one of the text boxes for use in rendering the selected one of the text characters on the display device if the center of the selected one of the text characters, when rendered in the one of the text boxes, will not be within the range of the line segment associated with the one of the text boxes.

4. The computer-implemented method of claim 3, wherein reading a set of encoding data for the one of the text characters includes reading encoding data specifying the width of the one of the text characters.

5. The computer-implemented method of claim 1, wherein determining if the center of the one of the text characters, when rendered in the one of the text boxes, will be within the range of the line segment associated with the one of the text boxes includes reading a set of encoding data for the one of the text characters, the encoding data specifying the center of the one of the text characters in at least one direction.

6. The computer-implemented method of claim 1, wherein forming a text box for each of the plurality of line segments includes forming each of the text boxes oriented along a length of an associated one of the line segments.

7. The computer-implemented method of claim 1, wherein forming a text box for each of the plurality of line segments includes forming each of the text boxes oriented along a length of an associated one of the line segments and having a length, in the direction of the length of the associated line segment, larger than the range of the associated line segment.

8. The computer-implemented method of claim 7, wherein forming a text box for each of the plurality of line segments includes forming each of the text boxes so that the start of each text box extends a predetermined distance, in the direction of the length of the associated line segment, before the start of the line segment and so that the end of the text box extends the predetermined distance, in the direction of the line segment, past the end of the line segment.

9. The computer-implemented method of claim 8, wherein the predetermined distance is half the width of one of the text characters of the text string stored in the image lookup table when formed in the text box.

10. The computer-implemented method of claim 7, wherein forming a text box for each of the plurality of line segments includes forming each of the text boxes so that the height of the text box extends a predetermined distance orthogonally to the direction of an associated line segment.

11. The computer-implemented method of claim 10, wherein the height of the text box is the height of one of the text characters of the text string stored in the image lookup table when formed in the text box.

12. The computer-implemented method of claim 1, further including using a fragment shader within the computer device to determine if the center of the one of the text characters, when rendered in the one of the text boxes, will be within the range of the line segment associated with the one of the text boxes and to render the one of the text characters on the display device using the one of the text boxes if the one of the text characters when rendered in the one of the text boxes will be within the range of the line segment associated with the one of the text boxes.

13. An image rendering engine, comprising;

a communications network interface;

a processor;

a memory coupled to the processor;

a display device coupled to the processor;

a first routine, stored in the memory, that executes on the processor to receive, via the communications network interface, a set of vector data comprising data defining one or more image objects and to obtain from the memory one or more text string lookup tables, wherein one of the text string lookup tables stores text characters of at least one text string as a set of pixelated text characters and encoding data defining the center position of each of a plurality of text characters associated with the text string;

a second routine, stored in the memory, that executes on the processor to determine a plurality of line segments associated with a line along which the text string is to be rendered, and a range associated with each line segment, wherein at least two of the plurality of line segments are at an angle with each other;

a third routine, stored in the memory, that executes on the processor to determine a text box for each of the plurality of line segments, each of the text boxes being oriented to draw text in an upright position along an associated line segment, the text box having a horizontal component along the range of the line segment and a vertical component perpendicular to the range of the line segment; and

a fourth routine, stored in the memory, that executes on the processor to;

select one of the text boxes in which to render a text character of the text string, wherein the one of the text boxes is associated with one of the at least two line segments that are at an angle with each other;

select one or more pixels of a next one of the text characters of the text string;

determine if a center of the next one of the text characters, when rendered in the selected one of the text boxes on the image, will be within the range of the line segment associated with the selected one of the text boxes; and

render the pixels of the one of the text characters on the display device using the one of the text boxes if a center of the one of the text characters when rendered in the selected one of the text boxes will be within the range of the line segment associated with the selected one of the text boxes and not render the pixels of the one of the text characters on the display device using the one of the text boxes if a center of the one of the text characters when rendered in the one of the text boxes will not be within the range of the line segment associated with the one of the text boxes.

14. The image rendering engine of claim 13, wherein the third routine comprises a vertex shader.

15. The image rendering engine of claim 13, wherein the fourth routine comprises an application that uses a fragment shader.

16. The image rendering engine of claim 13, where the fourth routine selects pixels for each one of the text characters of the text string stored within the image lookup table in turn and, for each selected one of the text characters;

determines if the center of the selected one of the text characters, when rendered in the one of the text boxes, will be within the range of the line segment associated with the one of the text boxes,

renders the selected one of the text characters on the display device using the one of the text boxes if the center of the selected one of the text characters when rendered in the one of the text boxes will be within the range of the line segment associated with the one of the text boxes, and

selects a different one of the plurality of text boxes that is associated with a second of the at least two line segments that are at an angle with each other as the one of the text boxes for use in rendering the selected one of the text characters on the display device if the center of the selected one of the text characters, when rendered in the one of the text boxes, will not be within the range of the line segment associated with the one of the text boxes.

17. The image rendering system of claim 13, wherein the fourth routine determines if the center of the one of the text characters, when rendered in the one of the text boxes, will be within the range of the line segment associated with the one of the text boxes by reading a set of encoding data for the one of the text characters, the encoding data specifying the center of the one of the text characters in at least one direction and using the location of the center of the one of the text characters to determine if the center of the one of the text characters, when rendered in the one of the text boxes, will be within the range of the line segment associated with the one of the text boxes.

18. The image rendering system of claim 13, wherein the third routine forms a text box for each of the plurality of line segments by forming a text box oriented along a length of an associated one of the line segments.

19. The image rendering system of claim 18, wherein the fourth routine forms each of the text boxes oriented along the length of an associated one of the line segments such that each of the text boxes has a length, in the direction of the length of the associated line segment, larger than the range of the associated line segment.

20. A method of rendering text along a line within an image being rendered on a display device, comprising:

storing a text string lookup table in a computer memory, the text string lookup table including a multiplicity of text characters associated with a text string and encoding data defining a center position of each of the multiplicity of text characters associated with the text string;

determining using a computer device a plurality of line segments associated with a line in the image along which the text string is to be rendered and a range associated with each line segment, wherein at least two of the plurality of line segments are at an angle with each other;

forming a text box for each of the plurality of line segments using the computer device, each of the text boxes being oriented to draw text in an upright position along an associated line segment in the image, the text box having a horizontal component along the range of the line segment and a vertical component perpendicular to the range of the line segment; and

for each text character in the text string;

selecting one of the text boxes in which to render the text character of the text string using the computer device, wherein the one of the text boxes is associated with one of the at least two line segments that are at an angle with each other;

reading the encoding data from the text string lookup table using the computer device and determining if the center position of the text character, when rendered in the selected one of the text boxes, will be within the range of the line segment associated with the selected one of the text boxes; and

rendering the text character in the image on the display device using the selected one of the text boxes if the center position of the text character when rendered in the selected one of the text boxes will be within the range of the line segment associated with the selected one of the text boxes or otherwise selecting a different one of the plurality of text boxes as the selected one of the text boxes if the center position of the text character, when rendered in the selected one of the text boxes, will not be within the range of the line segment associated with the selected one of the text boxes.

21. A method of rendering text along a line of claim 20, wherein reading the encoding data from the text string lookup table for one of the text characters includes reading encoding data specifying the center position of the one of the text characters in a direction along the length of the text string.

22. A method of rendering text along a line of claim 21, wherein reading the encoding data from the text string lookup table for the one of the text characters includes reading encoding data specifying the width of the one of the text characters along the length of the text string.

23. A method of rendering text along a line of claim 20, wherein forming a text box for each of the plurality of line segments includes forming each text box oriented along a length of an associated one of the plurality of line segments.

24. A method of rendering text along a line of claim 20, wherein forming a text box for each of the plurality of line segments includes forming each text box oriented along a length of an associated one of the line segments and having a length, in the direction of the length of the associated line segment, larger than the range of the associated line segment.

25. A method of rendering text along a line of claim 24, wherein forming a text box for each of the plurality of line segments includes forming each text box so that the start of each text box extends a predetermined distance, in the direction of the length of the associated line segment, before the start of the line segment and so that the end of each text box extends the predetermined distance, in the direction of the line segment, past the end of the associated line segment.

26. A method of rendering text along a line of claim 25, wherein the predetermined distance is half the width of one of the multiplicity of text characters associated with the text string when formed in the text box.

27. A method of rendering text along a line of claim 25, wherein forming a text box for each of the plurality of line segments includes forming each text box so that the height of the text box extends a predetermined distance orthogonally to the direction of an associated line segment.

28. A method of rendering text along a line of claim 27, wherein the height of the text box is the height of one of the multiplicity of text characters associated with the text string when formed in the text box.

29. A method of rendering text along a line of claim 20, wherein storing the text string lookup table in a computer memory includes storing encoding data defining a center position of each of the multiplicity of text characters associated with the text string as a pixel value for each column of pixels of the text string.

30. A method of rendering text along a line of claim 20, wherein storing the text string lookup table in a computer memory includes storing encoding data defining a center position of each of the multiplicity of text characters associated with the text string as a pixel value for each column of pixels of the text string, wherein a particular pixel value is used to define a center position of a text character and pixel values that are incremented or decremented from the particular pixel value are used to indicate at each pixel column of a text character, a distance to the center position of the text character.

31. A method of rendering text along a line of claim 20, wherein storing the text string lookup table in a computer memory includes storing a set of glyphs within a field of glyphs in the text string lookup table, and storing further encoding data for each text character within the text string, the further encoding data referencing one of the glyphs to use as the text character at a position within the text string.

32. A method of rendering text along a line of claim 31, including storing the encoding data and the further encoding data as being correlated to one another by location in the text string lookup table.

33. A map image rendering system, comprising:

a database that stores map-related vector image data, the vector image data comprising data defining one or more image objects and one or more text string lookup tables, wherein one of the text string lookup tables stores text characters associated with at least one text string to be rendered as a set of pixelated text characters and encoding data defining the center position of each of a plurality of text characters associated with the text string; and

a map image rendering device communicatively coupled to the database to use the map-related vector image data and to render a map image using the map-related vector image data, the map image rendering device including;

a processor,

a memory coupled to the processor,

a display device coupled to the processor,

one or more applications stored on the memory which, when executed on the processor;

determine a plurality of line segments associated with a line along which a text string is to be rendered and a range associated with each line segment, wherein at least two of the plurality of line segments are at an angle with each other;

form a text box for each of the plurality of line segments, each of the text boxes being oriented to draw text in an upright position along an associated line segment in the image and having a set of range values defined by the range of the associated line segment, the text box having a horizontal component along the range of the line segment and a vertical component perpendicular to the range of the line segment; and

for each text character in the text string,

(1) read the encoding data from the text string lookup table;

(2) determine the text box having a range value in which the center position of the text character will fall when the text character is rendered on the image; and

(3) render the text character as part of the image on the display device using the determined one of the text boxes.

34. A map image rendering system of claim 33, wherein the encoding data further defines a width of each of the text characters associated with the text string.

35. A map image rendering system of claim 33, wherein the one or more applications includes one or more image shaders that form a text box for each of the plurality of line segments by forming each of the text boxes oriented along a length of an associated one of the line segments and having a length, in the direction of the length of the associated line segment, larger than the range of the associated line segment.

36. A map image rendering system of claim 35, wherein the one or more image shaders form a text box for each of the plurality of line segments so that the start of each text box extends a predetermined distance, in the direction of the length of the associated line segment, before the start of the line segment and so that the end of the text box extends the predetermined distance, in the direction of the line segment, past the end of the line segment.

37. A map image rendering system of claim 33, wherein one of the text string lookup tables stores the encoding data defining a center position of each of the text characters associated with a text string as a pixel value for each column of pixels of the text string, wherein a particular pixel value is used to define a center position of a text character and other pixel values are incremented or decremented from the particular pixel value to indicate at each pixel column of a text character, a distance to the center position of the text character.

38. A map image rendering system of claim 33, wherein one of the text string lookup tables further stores a set of glyphs within a field of glyphs in the text string lookup table, and stores further encoding data for each text character associated with the text string, the further encoding data referencing one of the glyphs to use as the text character at a position within the text string.

39. A map image rendering system of claim 33, wherein the one or more image shaders determine the text box having a range value in which the center position of the text character will fall when the text character is rendered on the image by;

selecting one of the text boxes in which to render the text character of the text string, wherein the one of the text boxes is associated with one of the at least two line segments that are at an angle with each other,

determining if the center position of the text character, when rendered in the selected one of the text boxes, will be within the range of the line segment associated with the selected one of the text boxes, and

rendering the text character in the image on the display device using the selected one of the text boxes if the center position of the text character when rendered in the selected one of the text boxes will be within the range of the line segment associated with the selected one of the text boxes or otherwise selecting a different one of the plurality of text boxes associated with a second one of the at least two line segments that are at an angle with each other as the selected one of the text boxes if the center position of the text character, when rendered in the selected one of the text boxes, will not be within the range of the line segment associated with the selected one of the text boxes.