Abstract: A map database stores map data in multiple levels having different levels of details. In displaying a three-dimensional map, the map data having a higher level of details is used for a close view area near the viewpoint to a predetermined distance, and the map data having a lower level of details is used for a distant view area farther from the predetermined distance. The distant view area is first drawn by a perspective projection, and then, after clearing a depth buffer that stores depth information, the close view area is drawn, such that an undesirable hidden line removal process based on the depth information is not performed between the projected image in the distant view area and that in the close view area, thereby avoiding an unnatural phenomenon in which part of the close view image is hidden by the distant view image.

Abstract: A three-dimensional map is displayed over the whole display area with a relatively light load using a detailed model database including feature data with a higher accuracy of details and a simple model database including feature data with a lower accuracy of details. A first range is set within a predetermined distance from a view point in a line-of-sight direction as a detailed model drawing range in which a detailed three-dimensional map is drawn using the detailed model. A second range in which a simple three-dimensional map is drawn using the simple model is set to include a range where the detailed three-dimensional map is not drawn. The detailed three-dimensional map and the simple three-dimensional map are both displayed by superimposing the detailed three-dimensional map in front of the simple three-dimensional map.

Abstract: A projection (projected image) is drawn by perspective projection of a three-dimensional model with a background image having improved reality. When a sightline of the perspective projection looks down from above, the projected image is drawn into an object drawing area which is a lower part of an image picture. A background layer representing the stratosphere is separately generated by two-dimensionally drawing a background image, in which the stratosphere (hatched area) is opaque, while the remaining area is transparent. The boundary between the opaque portion and the transparent portion forms a curved line that is convex upward to express a curved horizon. The background layer is superimposed in front of the projected image, not behind the projected image, thereby covering an upper edge portion of the projected image including a straight-lined upper edge, so as to provide a curved boundary realizing a curved pseudo horizon in the image picture.

Abstract: A three-dimensional (3D) map display system displays a 3D map on which a ground surface and a feature are represented three-dimensionally. The 3D map display system includes (a) a map database for storing map data representing a 3D shape of the ground surface and the feature, (b) a first drawing unit for drawing the ground surface and the feature by executing depth determination by referring to the map database, and (c) a second drawing unit for drawing a target feature, which is a feature in which at least a part thereof is hidden by a ground surface or other features in the drawing by the first drawing unit, by overwriting the target feature on a drawing result by the first drawing unit by using the map data without executing depth determination with respect to the drawing result by the first drawing unit.

Abstract: A map database stores three-dimensional polygons of features, as well as water system polygons such as sea and lake and ground surface polygons. The map database stores map data in multiple levels having different levels of details, such as levels LVa to LVc. A procedure of displaying a three-dimensional map offsets the water systems relative to the ground surfaces, draws a map of a distant view area distant away from the viewpoint using map data at a low level of details, subsequently clears a depth buffer and newly draws a map of a close view area close to the viewpoint using map data at a high level of details. The offset is set to increase in the distant view area and decrease in the close view area. Increasing the offset in the distant view area avoids the occurrence of Z-fighting in the distant area from the viewpoint.

Abstract: A three-dimensional map is displayed in a bird's eye view with a stereoscopic effect of feature polygons by providing shading in an appropriate direction according to the gaze direction in a simulative manner. Shading wall polygons are set in addition to feature polygons in three-dimensional map data. The shading wall polygon is a virtual plate-like polygon provided vertically, for example, along a boundary of a feature polygon. When provided around the water system, the shading wall polygon is specified to be opaque on one surface viewed from the water system side and to be transparent on the opposite surface. The shading wall polygons are drawn along with the feature polygons in the process of displaying a map. The shading wall polygon is drawn in black, gray or the like only at a location where the surface specified to be opaque faces a gaze direction.

Abstract: In displaying a 3D map, a feature image is generated by perspective projection of the feature based on a predetermined position of the point of sight and a predetermined direction of the line of sight. A plate polygon on which characters are pasted is arranged in a virtual 3D space in a direction along a road and tilted from the ground surface, and parallel projection is applied to the plate polygon so as to generate a character image. A tilt angle between the plate polygon and the ground surface is set based on a display direction of the road and a display position of the character. Thus, by generating the feature image by perspective projection while generating the character image by parallel projection, negative effects such as crushing of distant characters can be avoided, whereby the characters can be displayed in three-dimensional shape without reducing visibility thereof.

Abstract: Representation of undulation with a light processing load is realized using three-dimensional ground surface data. Ground surface data representing a three-dimensional shape of a ground surface is stored in a map database. A two-dimensional image representing contrast of the ground surface is also generated by projecting the ground surface data by applying lighting thereto, and the two-dimensional image is stored in map data as a ground surface texture. In displaying the map, the ground surface texture is pasted on the ground surface data and perspective projection is performed. By such a configuration, even without applying lighting, a map can be provided which can give undulation of a ground surface with a light processing load.

Abstract: A 3D map representing a feature that cannot be visually recognized such as an underground structure is displayed without a sense of discomfort. Among features stored in the map database, underground structures such as tunnels are classified into transmissive objects, and other features into non-transmissive objects. Then, the transmissive objects and the non-transmissive objects are projected individually so as to generate a transmissive object projection view and a non-transmissive object projection view. The transmissive object projection view thus obtained is superposed on the non-transmissive object projection view with adjusted transmittance. Making the transmissive objects to be transmissive and superposing them enables to realize a map that appears to the user as if a ground surface or features which blocked the transmissive objects are made to be transmissive whereby the transmissive objects become visible.

Abstract: A thee-dimensional (3D) map display system displays a 3D map on which a ground surface and a feature are represented three-dimensionally. The 3D map display system includes (a) a map database for storing map data representing a 3D shape of the ground surface and the feature, (b) a first drawing unit for drawing the ground surface and the feature by executing depth determination by referring to the map database, and (c) a second drawing unit for drawing a target feature, which is a feature in which at least a part thereof is hidden by a ground surface or other features in the drawing by the first drawing unit, by overwriting the target feature on a drawing result by the first drawing unit by using the map data without executing depth determination with respect to the drawing result by the first drawing unit.

Abstract: A three-dimensional map display system displays a three-dimensional map representing features thereon three-dimensionally. The system includes a map database, a projection view generation unit, and an attribute representation image superimposing unit. The map database stores drawing data including a three-dimensional model of a feature and appearance attribute information representing an appearance attribute of the feature, by associating the drawing data and the appearance attribute information with each other. The projection view generation unit generates a projection view by projecting the drawing data.

Abstract: A drawing data generation device performs an integration process on map data so as to integrate line data for drawing linear features such as roads, such that a drawing speed of a map image is improved. The line data is grouped by the line type and the line width. The integration process links thin solid lines L1 and L3 by a non-display line LA1, and links thick solid lines L2, L4 and L5 by non-display lines LA2 and LA3, for example, so as to integrate the line data of a plurality of lines into integrated line data for an integral line formed of linked lines in a same group.

Abstract: A projection (projected image) is drawn by perspective projection of a three-dimensional model with a background image having improved reality. When a sightline of the perspective projection looks down from above, the projected image is drawn into an object drawing area which is a lower part of an image picture. A background layer representing the stratosphere is separately generated by two-dimensionally drawing a background image, in which the stratosphere (hatched area) is opaque, while the remaining area is transparent. The boundary between the opaque portion and the transparent portion forms a curved line that is convex upward to express a curved horizon. The background layer is superimposed in front of the projected image, not behind the projected image, thereby covering an upper edge portion of the projected image including a straight-lined upper edge, so as to provide a curved boundary realizing a curved pseudo horizon in the image picture.

Abstract: A map database stores map data in multiple levels having different levels of details. In displaying a three-dimensional map, the map data having a higher level of details is used for a close view area near the viewpoint to a predetermined distance, and the map data having a lower level of details is used for a distant view area farther from the predetermined distance. The distant view area is first drawn by a perspective projection, and then, after clearing a depth buffer that stores depth information, the close view area is drawn, such that an undesirable hidden line removal process based on the depth information is not performed between the projected image in the distant view area and that in the close view area, thereby avoiding an unnatural phenomenon in which part of the close view image is hidden by the distant view image.

Abstract: A map database stores three-dimensional polygons of features, as well as water system polygons such as sea and lake and ground surface polygons. The map database stores map data in multiple levels having different levels of details, such as levels LVa to LVc. A procedure of displaying a three-dimensional map offsets the water systems relative to the ground surfaces, draws a map of a distant view area distant away from the viewpoint using map data at a low level of details, subsequently clears a depth buffer and newly draws a map of a close view area close to the viewpoint using map data at a high level of details. The offset is set to increase in the distant view area and decrease in the close view area. Increasing the offset in the distant view area avoids the occurrence of Z-fighting in the distant area from the viewpoint.

Abstract: A three-dimensional map effectively uses a space of the sky or the background to display character strings. A transmitter/receiver obtains map data used to display each feature three-dimensionally and character data representing a character string to be displayed in the three-dimensional map from a map database. A feature image generator generates a feature image in which each feature is drawn three-dimensionally. A character display controller controls display of the character string on the feature image. The character display controller changes over at least one of a display direction and a number of display lines of the character string with respect to each of a plurality of areas in the feature image specified according to a distance from a viewpoint set for generating the feature image, such that a length of the character string in a vertical direction increases with a decrease in distance from the viewpoint.

Abstract: A three-dimensional map is displayed in a bird's eye view with a stereoscopic effect of feature polygons by providing shading in an appropriate direction according to the gaze direction in a simulative manner. Shading wall polygons are set in addition to feature polygons in three-dimensional map data. The shading wall polygon is a virtual plate-like polygon provided vertically, for example, along a boundary of a feature polygon. When provided around the water system, the shading wall polygon is specified to be opaque on one surface viewed from the water system side and to be transparent on the opposite surface. The shading wall polygons are drawn along with the feature polygons in the process of displaying a map. The shading wall polygon is drawn in black, gray or the like only at a location where the surface specified to be opaque faces a gaze direction.

Abstract: A route guidance device is provided with a two-dimensional road network for a route search, a three-dimensional road network for a route guidance, and guiding line shape data. The guiding line shape data is three-dimensional guidance display data for guiding an operator to go straight through, or to make a right turn, left turn, etc. at intersections in accordance with a passage mode, or to switch lanes before entering an intersection. A link node of the two-dimensional road network is associated with the guiding line shape data through the three-dimensional road network. The route search uses the two-dimensional road network, and the route guidance uses the guiding line shape data associated with the link node acquired by the route search. The present invention can realize an instinctively understandable route guidance that follows a passage mode without increasing a load of a route search.

Abstract: A three-dimensional map is provided by preserving its scale. The three-dimensional map is drawn based on prepared landscape feature data which three-dimensionally draws roads, buildings, and other landscape features. The landscape feature data is generated by a parallel projection method which projects an actual landscape feature (CST2) upon a projection plane (PL2) with parallel lines along the projection direction (PRJ), rather than a perspective projection. The landscape feature data is provided by either two-dimensional raster data or polygonal data that draws a parallel projected projection map. It is possible to draw the three-dimensional map by only drawing the prepared landscape feature data, without rendering or other load-intensive processing. Unlike the perspective projection, the parallel projection preserves the positional relationships among buildings and the scale of shapes, so as to provide a three-dimensional map in which the scale is preserved.

Abstract: It is an object to realize a route guidance that follows a real passage mode without a feeling of wrongness. In a route guidance device, aside from a two-dimensional road network for a route search, a three-dimensional road network used for the route guidance and guiding line shape data are prepared. The guiding line shape data are three-dimensional guidance display data that guide you to go straight through a crossroads, to turn right, to turn left, etc. in accordance with a passage mode or guide you to change a car lane before you enter a crossroads. A link node of the two-dimensional road network is associated with the guiding line shape data through the three-dimensional road network. The route search is carried out by using the two-dimensional road network. The route guidance is carried out by using the guiding line shape data associated with the link node acquired by the route search.