Method and apparatus for generating an orthorectified tile

• US 20100091017A1
• Filed: 10/09/2007
• Published: 04/15/2010
• Est. Priority Date: 10/09/2006
• Status: Active Grant

• Current Assignee: Tomtom Global Content B.V (TomTom NV)
• Original Assignee: Tomtom Global Content B.V (TomTom NV)
• Inventors: Kmiecik, Marcin Michal, Nowak, Wojciech Tomasz
• Granted Patent: US 8,847,982 B2
• Time in Patent Office: Days
• US Class Current: 345/420
• CPC Class Codes: G01C 11/02 Picture taking arrangements specially adapted for photogrammetry or photographic surveying, e.g. controlling overlapping of pictures
• CPC Class Codes: G01C 21/3822 Road feature data, e.g. slope data
• CPC Class Codes: G01C 21/3848 Data obtained from both position sensors and additional sensors
• CPC Class Codes: G01C 21/3881 Tile-based structures
• CPC Class Codes: G06T 3/00 Geometric image transformations in the plane of the image
• CPC Class Codes: G06T 3/4038 Image mosaicing, e.g. composing plane images from plane sub-images
• CPC Class Codes: G06T 5/006 Geometric correction correction of chromatic aberrations adapted to be used in an image pickup device containing an electronic image sensor H04N23/10; detecting, correcting, reducing or removing artefacts resulting only from the lens unit, e.g. flare, shading, vignetting or "cos4" H04N25/61
• CPC Class Codes: G06T 5/80 Geometric correction
• CPC Class Codes: G09B 29/102 using electrical means
• CPC Class Codes: G11C 11/02 using magnetic elements

Abstract

A method is disclosed for generating an orthorectified tile. In at least one embodiment, the method includes retrieving source images obtained by way of a terrestrial based camera; retrieving position data associated with the source images; retrieving orientation data associated with the source images; and converting source image by means of corresponding position data and orientation data to obtain the orthorectified tile. Orthorectified tiles are used to generate an orthorectified mosaic. As such, images recorded by terrestrial based camera may be used to generate a map of a road surface with corresponding road signs.

Claims

1. Method for generating an orthorectified tile comprising:

—

retrieving a sequence of source images obtained by a terrestrial based camera mounted on a moving vehicle driving across a surface of the earth;

retrieving position data associated with the retrieved source images, wherein the retrieved position data includes constant position parameters defining a relationship with a reference position within the vehicle and variable parameters in a geographic coordinate reference system corresponding to a coordinate location of the vehicle'"'"'s reference position in said coordinate reference system;

—

retrieving orientation data associated with the retrieved source images, wherein the retrieved orientation data includes constant orientation parameters having a relationship with the orientation of the camera with respect to a reference orientation of the vehicle and variable orientation parameters in the geographic coordinate reference system corresponding to the orientation of the reference orientation of the vehicle in the coordinate reference system;

—

converting a source image by way of corresponding position data and orientation data to obtain the orthorectified tile and corresponding metadata defining a conversion of pixel coordinates in an orthorectified image to a position in the geographic coordinate reference system.

2. Method according to claim 1, further comprising:

—

estimating a plane corresponding to the earth surface in dependence of the position and orientation data associated with the source images; and

converting uses the plane to convert a source image to obtain the orthorectified tile.

3. Method according to claim 2, wherein the orthorectified tile comprises pixels, and said converting includes:

—

determining at least one pixel in the source image corresponding to a pixel of the orthorectified tile; and

—

determining the value of the pixel of the orthorectified tile from the values of the at least one pixel in the source image.

4. Method according to claim 2, wherein a shape of the orthorectified tile is a rectangle.

5. Method according to claim 1, wherein the sequence of source images is retrieved by a camera mounted on a vehicle moving over a surface of the earth, and wherein the orientation data include variable orientation parameters having a relationship with an angle between a defined orientation of the vehicle and the driving direction of the vehicle.

6. Method according to claim 1, wherein the sequence of source images is retrieved by a camera mounted on a vehicle moving over the surface of the earth, and wherein the orientation data include variable orientation parameters having a relationship with an angle between a plane defined by the road surface and a horizontal plane.

7. Method according to claim 6, wherein at least one of the variable orientation parameters has a relationship with an angle between the plane defined by the road surface below the moving vehicle and a horizontal plane.

8. Method according to claim 1, wherein the converting includes:

—

correcting geometric distortion in the source images;

—

performing a 3D rotation over a focal point of the camera so as to obtain a vertical image; and

—

converting the vertical image into an orthorectified tile.

9. Method for generating an orthorectified mosaic comprising:

generating orthorectified tiles from source images obtained by a terrestrial based camera mounted on a moving vehicle driving across a surface of-the earth by the method according to claim 1;

—

and

generating the orthorectified mosaic and metadata from the generated orthorectified tiles and corresponding metadata.

10. Method according to claim 9, wherein generating of the orthorectified mosaic includes:

—

defining a projected coordinate reference system for the orthorectified mosaic from the position data;

—

determining an area of orthorectified tile in the orthorectified mosaic by way of the projected coordinate reference system and metadata corresponding to the orthorectified tile;

—

and

converting pixels of the determined area of the orthorectified tile into pixels of the orthorectified mosaic.

12. A processor readable storage medium carrying an orthorectified mosaic obtained by the method according to claim 9.

13. A computer program product, comprising instructions which, when loaded on a computer arrangement, allows the computer arrangement to perform the method according to claim 1.

14. A processor readable medium carrying a computer program product which, when loaded on a computer arrangement, allows the computer arrangement to perform the method according to claim 1.

18. Method according to claim 3, wherein a shape of the orthorectified tile is a rectangle.

19. A processor readable storage medium carrying an orthorectified mosaic obtained by the method according to claim 10.

20. A computer readable medium including program segments for, when executed on a computer device, causing the computer device to implement the method of claim 1.

11. A computer arrangement comprising:

—

an input device;

—

a processor readable storage medium;

—

a processor in communication with said input device and said processor readable storage medium; and

an output device in communication with the processor, said processor readable storage medium storing code to program said processor to perform a method comprising;

—

retrieving a sequence of source images obtained by terrestrial based camera mounted on a moving vehicle driving across a surface of the earth;

—

retrieving position data associated with the retrieved source images, wherein the position data includes constant position parameters defining a relationship with the reference position within the vehicle and variable parameters in a geographic coordinate reference system corresponding to the coordinate location of the vehicle'"'"'s reference position in the coordinate reference system;

—

retrieving orientation data associated with the retrieved source images, wherein the retrieved orientation data include constant orientation parameters having a relationship with the orientation of the camera with respect to a defined orientation of the vehicle and variable orientation parameters in the geographic coordinate reference system corresponding to the orientation of the reference orientation of the vehicle in the coordinate reference system;

—

converting source images by way of the corresponding position data and orientation data to obtain orthorectified tiles and corresponding metadata defining a conversion of pixel coordinates to positions in the geographic coordinate reference system;

—

generating an orthorectified mosaic and corresponding metadata from the obtained orthorectified tiles; and

—

storing the orthorectified mosaic and associated metadata on the processor readable storage medium.

15. Method of collecting both positionally accurate horizontal information and positionally accurate vertical information from source images of at least one terrestrial based image sequence obtained by a terrestrial based camera mounted on a moving vehicle driving across a surface of the earth, the method comprising:

—

retrieving source images;

—

retrieving position data associated with the retrieved source images, wherein the position data includes constant position parameters defining a relationship with a reference position within the vehicle and variable parameters in a geographic coordinate reference system corresponding to the coordinate location of the vehicle'"'"'s reference position in the coordinate reference system;

—

retrieving orientation data associated with the retrieved source images, wherein the orientation data includes constant orientation parameters having a relationship with an orientation of the camera with respect to a reference orientation of the vehicle and variable orientation parameters in the geographic coordinate reference system corresponding to the orientation of the reference orientation of the vehicle in the coordinate reference system;

—

retrieving horizontal information and corresponding position in the geographic coordinate reference system from the retrieved source images, wherein the position has been obtained by converting at least partially source images including at least partially the horizontal information by way of position data and orientation data associated with the source images to obtain an orthorectified representation of the horizontal information, the orthorectified representation including image data and metadata defining the conversion of pixel coordinates of the orthorectified representation to a position in the geographic coordinate reference system;

—

retrieving vertical information from at least one source image and locating the position of said vertical information by way of the position data and orientation data associated with the source images; and

—

storing the retrieved vertical and horizontal information and associated positions for use in a map database.

21. A computer readable medium including program segments for, when executed on a computer device, causing the computer device to implement the method of claim 15.

16. (canceled)

17. Method of collecting both positionally accurate horizontal information and positionally accurate information regarding an object from at least one source image obtained by a terrestrial based camera mounted on a moving vehicle driving across the earth surface, wherein an attachment point at which the object is attached to the ground is visible in at least one pixel of the at least one source image, the method comprising:

—

retrieving the at least one source image;

—

retrieving position data associated with the retrieved at least one source image, wherein the position data includes constant position parameters defining a relationship with a reference position within the vehicle and variable parameters in a geographic coordinate reference system corresponding to a coordinate location of the vehicle'"'"'s reference position in the coordinate reference system;

—

retrieving orientation data associated with the at least one source image, wherein the orientation data includes constant orientation parameters having a relationship with the orientation of the camera with respect to a reference orientation of the vehicle and variable orientation parameters in said geographic coordinate reference system corresponding to the orientation of the reference orientation of the vehicle in the coordinate reference system;

—

retrieving horizontal information and corresponding position in the geographic coordinate reference system from the retrieved at least one source image, wherein the position has been obtained by determining by way of the position data and orientation data associated with the retrieved at least one source image, an orthorectified position of at least one source image pixel associated to horizontal information;

—

retrieving object information from the retrieved at least one source image;

—

determining the at least one pixel corresponding to the attachment point of the object to the ground and determining, by way of the position data and orientation data associated with the at least one source image, the orthorectified position in the geographic coordinate reference system of at least one pixel corresponding to the attachment point of the object to the ground;

—

and

storing the retrieved object information and horizontal information and associated positions in the geographic coordinate reference system for use in a map database.

22. A computer readable medium including program segments for, when executed on a computer device, causing the computer device to implement the method of claim 17.