Method, apparatus and system for selecting a frame

• US 20150098645A1
• Filed: 10/02/2014
• Published: 04/09/2015
• Est. Priority Date: 10/04/2013
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: LEUNG, KA MING
• Granted Patent: US 9,811,733 B2
• Time in Patent Office: Days
• US Class Current: 382/154
• CPC Class Codes: G06F 16/786 using motion, e.g. object motion or camera motion
• CPC Class Codes: G06T 7/55 from multiple images
• CPC Class Codes: G06V 20/10 Terrestrial scenes scenes under surveillance with static cameras G06V20/52; scenes perceived from the exterior of a vehicle G06V20/56; scenes perceived from the interior of a vehicle G06V20/59

Abstract

A method of selecting a frame from a plurality of video frames captured by a camera (120). The method determines features to which map points in a three dimensional space are projected. A histogram of the determined features for a plurality of regions in the frame is created. One of the regions may be determined as being an unmapped region based on the created histogram. The frame is selected based on the size of the unmapped region.

Claims

1. A method of selecting a frame from a plurality of video frames captured by a camera, said method comprising:

determining features to which map points in a three dimensional space are projected;

creating a histogram of the determined features for a plurality of regions in the frame;

determining one of the regions as being an unmapped region based on the created histogram; and

selecting the frame based on the size of the unmapped region.

2. The method according to claim 1, further comprising prioritising the frame based on the size of the unmapped region.

3. The method according to claim 1, further comprising:

projecting the unmapped region at a viewpoint associated with a previous frame;

determining a size of the projected unmapped region within the previous frame; and

determining a ratio of the determined size to the projected unmapped region, wherein the frame is selected based on at least one of the determined size and the determined ratio.

4. The method of claim 1, further comprising projecting the unmapped region at a viewpoint associated with a previous frame, wherein the projection of the unmapped region is based on position and orientation of the camera at the viewpoint.

5. The method according to claim 1, further comprising determining if a number of features in a sub-image region of the selected frame are less than a predetermined threshold.

6. The method according to claim 1, further comprising determining if density of features in a sub-image region are less than a predetermined threshold.

7. The method according to claim 1, further comprising determining if the size of an unmapped region is larger than a predetermined threshold.

8. The method according to claim 1, wherein a size of a predefined region is used to determine the unmapped region.

9. The method according to claim 1, wherein the number of features in a predefined region is used to determine the unmapped region.

10. An apparatus for selecting a frame from a plurality of video frames captured by a camera, said apparatus comprising:

means for determining features to which map points in a three dimensional space are projected;

means for creating a histogram of the determined features for a plurality of regions in the frame;

means for determining one of the regions as being an unmapped region based on the created histogram; and

means for selecting the frame based on the size of the unmapped region.

11. A system selecting a frame from a plurality of video frames captured by a camera, said system comprising:

a memory for storing data and a computer program;

a processor coupled to the memory for executing the computer program, the computer program comprising instructions for;

determining features to which map points in a three dimensional space are projected;

creating a histogram of the determined features for a plurality of regions in the frame;

determining one of the regions as being an unmapped region based on the created histogram; and

selecting the frame based on the size of the unmapped region.

12. A computer readable medium having a computer program stored thereon for selecting a frame from a plurality of video frames captured by a camera, said processor comprising:

code for determining features to which map points in a three dimensional space are projected;

code for creating a histogram of the determined features for a plurality of regions in the frame;

code for determining one of the regions as being an unmapped region based on the created histogram; and

code for selecting the frame based on the size of the unmapped region.