Rendering a text image using texture map character center encoding with character reference encoding

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. In doing so, the image rendering system creates and reads a texture map that stores pixelated text characters of the text strings to be rendered in the image as a set of glyphs and that also stores first encoding data defining the center position of each text character as stored in a glyph and second encoding data referencing the location of the glyph to be used as the text character. This center position encoding enables the system to determine whether, in any particular instance, a text character of a text string should be rendered in the image at a particular position along the line or at a different position along the line while maximizing the storage efficiency of the texture map used to store the text string by allowing text characters repeated in a text string to be stored only once in the texture map.