Cut-line steering methods for forming a mosaic image of a geographical area

• US 20100034483A1
• Filed: 08/05/2008
• Published: 02/11/2010
• Est. Priority Date: 08/05/2008
• Status: Active Grant

• Current Assignee: Pictometry International Corporation (Eagleview Technologies, Inc. /Wa/)
• Original Assignee: Pictometry International Corporation (Eagleview Technologies, Inc. /Wa/)
• Inventors: Bradacs, Robert, Giuffrida, Frank, Schultz, Stephen, Gray, Robert
• Granted Patent: US 8,588,547 B2
• Time in Patent Office: Days
• US Class Current: 382/284
• 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: G06T 11/60 Editing figures and text; Combining figures or text
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/10032 Satellite or aerial image; Remote sensing
• CPC Class Codes: G06T 2207/30184 Infrastructure
• CPC Class Codes: G06T 3/4038 Image mosaicing, e.g. composing plane images from plane sub-images
• CPC Class Codes: G06T 7/12 Edge-based segmentation

Abstract

A method for automatically steering mosaic cut lines along preferred routes to form an output mosaic image includes the step of creating an assignment map corresponding to the output mosaic image where each pixel has an initial designation of unassigned. Then, each pixel of the assignment map that intersects the preferred routes is marked as being a Preferred Cut Line pixel to divide the Assignment Map into one or more regions. For each region, a search is conducted to locate one or more source images that completely cover that region. If multiple source images completely covering the region are located, the method uses a Selection Heuristic to determine quality of coverage, and then designates each pixel in that region as being assigned to the source image determined to be best by the Selection Heuristic. For any remaining unassigned regions, the method searches for two or more source images whose combined footprint completely covers the region, and for each set of two or more combined images, a Pairing Heuristic is used for determining quality of coverage. Each pixel in the region is designated as being assigned to the two or more combined images determined best by the Pairing Heuristic. Then, the Preferred Cut Line pixels are redesignated to match the image assignments of their bounded regions, and the output mosaic image is formed by contributing pixel values from the source images based upon the designations set forth in the assignment map.

Claims

1. A method for automatically steering mosaic cut lines along preferred routes to form an output mosaic image, comprising the steps of:

creating an assignment map corresponding to the output mosaic image where each pixel has an initial designation of unassigned;

marking pixels of the assignment map that intersect the preferred routes as being Preferred Cut Line pixels to divide the Assignment Map into one or more regions that are bounded by Preferred Cut Line pixels or the edge of the Assignment Map;

for each region, searching for one or more source images that completely cover that region, and responsive to multiple source images completely covering the region, using a Selection Heuristic to determine quality of coverage, and then designating each pixel in that region as being assigned to the source image determined to be best by the Selection Heuristic;

for any remaining unassigned regions, searching for two or more source images whose combined footprint completely covers the region, and for each set of two or more combined images, using a Pairing Heuristic to determine quality of coverage, and then designating each pixel in the region as being assigned to the two or more combined images determined best by the Pairing Heuristic;

redesignating the Preferred Cut Line pixels to match the image assignments of their bounded regions;

forming the output mosaic image by contributing pixel values from the source images based upon the designations set forth in the Assignment Map.

2. The method of claim 1, wherein the step of forming the output mosaic image is defined further as stepping through each pixel in the Assignment Map and using the image assignment stored there to determine which pixel values of the source image or images to use for the actual image content of the output mosaic image.

3. The method of claim 1, wherein multiple source images are located that completely cover a particular region, and wherein the Selection Heuristic determines which source image is closest to nadir in the area covering the region.

4. The method of claim 1, wherein multiple source images are located that completely cover a particular region, and wherein the Selection Heuristic used determines which source image covers the largest number of surrounding preferred cut line pixels.

5. The method of claim 1, wherein multiple source images are located that completely cover a particular region, and wherein the Selection Heuristic used determines which source image covers the largest number of contiguous other regions.

6. The method of claim 1, wherein multiple source images are located that combine to completely cover a particular region, and wherein the Pairing Heuristic used determines which source image covers the largest number of pixels in the region, and then determines which source image covers the largest number of remaining uncovered pixels in the region.

7. The method of claim 1, wherein multiple source images are located that combine to completely cover a particular region, and wherein the Pairing Heuristic used determines which source image is closest to nadir at the center point of the region.

8. The method of claim 7, wherein the Pairing Heuristic used also determines which sub-regions are not covered by the source image that is closest to nadir at the center point of the region, and then determines which source image is closest to nadir with respect to each sub-region.

9. The method of claim 1, wherein the step of forming the output mosaic image is defined further as contributing pixel values from the source images based upon the designations set forth in the assignment map and feathering the pixel values along the preferred routes separating pixel values from different source images.

10. The method of claim 1, wherein the preferred routes are determined utilizing a ground confidence map.

11. The method of claim 1, wherein the ground confidence map is created via the method of claim 13.

12. The method of claim 1, wherein the preferred routes are determined utilizing street center line data.

13. A method for creating a ground confidence map of a geographic area, comprising the steps of:

selecting a plurality of geo-referenced, digital source images captured from different vantage points and cooperating to cover the geographic area, the source images having overlapping portions depicting a portion of the geographic area;

creating the ground confidence map of the geographic region, the ground confidence map having a plurality of pixels with each pixel corresponding to a particular geographic location;

assigning the pixels in the ground confidence map with a pixel value indicative of the ground confidence score by;

calculating a composite ground confidence score for the pixel values of common geographic regions within the overlapping portions of the source images within a kernel corresponding to the particular geographic location of the pixel; and

storing a pixel value indicative of the composite ground confidence score calculated for the particular pixel.

14. The method of claim 13, wherein the pixel values in the ground confidence map are the calculated ground confidence scores.

15. The method of claim 13, wherein the ground confidence map is stored on a computer readable medium in an image file.

16. A method for determining preferred routes for steering mosaic cut lines to form an output mosaic image, comprising the steps of:

generating a ground confidence map of a geographic area by analyzing overlapping portions of digital source images of the geographic area with such digital source images captured from different vantage points with respect to the geographic area, certain pixels of the ground confidence map indicating that a same geographic area in at least two of the overlapping source images represent the ground;

identifying contiguous pixels in the ground confidence map indicating that the same geographic area in at least two of the overlapping source images represent the ground; and

determining preferred routes for steering mosaic cut lines utilizing the identified contiguous pixels in the ground confidence map.