Method and apparatus for displaying road map in form of bird's eye view

An apparatus for displaying a road map mesh in a form of bird's eye view on a display unit, comprising:

• a memory arranged for storing the road map mesh in a form of a plan view;
• and
• a picture drawing processor arranged for placing a virtual viewpoint at an upper sky behind a predetermined point of display reference by a predetermined distance, looking down from the virtual viewpoint at the plan view formed road map mesh forward away from the predetermined point of display reference having an angle of field of view with respect to the predetermined point of display reference, setting the display screen on a plane perpendicular to a line of sight passing the viewpoint and the predetermined point of display reference on the plan view formed road map mesh to form a looking down angle to the plan view formed road map mesh, predefining a dot pattern representing a correspondent relationship between pixels of the plan view formed road map and those of the display screen, extracting a part of the pixels of the plan view formed road map mesh from the plan view formed road map which has the correspondent relationship of the dot pattern and simultaneously omitting the other part of the pixels thereof from the same plan view formed road map to enable the display of only a bird's eye view display region in the plan view formed road map mesh on the display screen, and displaying the extracted pixels on the display screen during moving of the virtual viewpoint according to a scrolling process.

A method f or displaying a road map mesh in a form of bird's eye view on a display screen of a display unit, comprising:

• a) storing the road map mesh in a form of a plan view;
• b) placing a virtual viewpoint at an upper sky behind a predetermined point of display reference on the plan view formed road map mesh by a predetermined distance;
• c) looking down from the virtual viewpoint at the plan view formed road map mesh forward away from the predetermined point of display reference having an angle of field of view with respect to the predetermined point of display reference;
• d) setting the display screen on a plane perpendicular to a line of sight passing the viewpoint and the predetermined point of display reference on the plan view formed road map mesh to form a looking down angle to the plan view formed road map mesh;
• e) virtually drawing straight lines from the virtual viewpoint to the plan view formed road map mesh passing through centers of the respective dots on the display screen to define the dot at a point of each straight line intersected with the plan view formed road map mesh as that corresponding to each dot that the display screen has;
• f) forming one image screen with a display color set the corresponding dots of the plan view formed road map mesh as the display color of the dots of the display screen to enable the display of a bird is eye view display region on the display screen;
• and
• g) displaying the bird's eye view display region of the plan view formed road map mesh on the display screen.

An apparatus for displaying a road map mesh in a form of bird's eye view on a display unit, comprising:

• a memory arranged for storing the road map mesh in a form of a plan view;
• and
• a picture drawing processor arranged for placing a virtual viewpoint at an upper sky behind a predetermined point of display reference by a predetermined distance, looking down from the virtual viewpoint at the plan view formed road map mesh forward away from the predetermined point of display reference having an angle of field of view with respect to the predetermined point of display reference, setting the display screen on a plans perpendicular to a line of sight passing the viewpoint and the predetermined point of display reference on the plan view formed road map mesh to form a looking down angle to the plan view formed road map mesh, virtually drawing straight lines from the virtual viewpoint to the plan view formed road map mesh passing through centers of the respective dots on the display screen to define the dot at a point of each straight line intersected with the plan view formed road map mesh as that corresponding to each dot that the display screen has:
• forming one image screen with a display color set the corresponding dots of the plan view formed road map mesh as the display color of the dots of the display screen to enable the display of a bird's eye view display region on the display screen;
• and displaying the bird's eye view display region of the plan view formed road map mash on the display screen.