Method and system for calibration of detection thresholds in video object detection

A method for detecting objects in a scene captured by a camera, the method comprising:

• capturing video of the scene,
• segmenting a first image in the video into at least a first scene area and a second scene area, the first and second scene areas having properties such that ease or difficulty of detecting objects is expected to differ between the first and second scene areas,
• setting a first object detection threshold for the first scene area,
• detecting a first object in the first scene area in the first image, a first confidence value for the detection of the first object being above the first object detection threshold,
• in a plurality of images subsequent to the first image, tracking the first object as it moves into the second scene area,
• determining a second confidence value for a detection of the first object in the second scene area,
• setting a second object detection threshold for the second scene area such that the second confidence value for the detection of the first object is above the second object detection threshold, and
• in subsequent images, using the first object detection threshold for detecting objects in the first scene area and the second object detection threshold for detecting objects in the second scene area;
• wherein:
• the first object is associated with a first object class,
• the method further comprising:
• setting the first object detection threshold for the first scene area comprises setting a first object detection threshold for objects of the first object class in the first scene area, and
• setting the second object detection threshold comprises setting a second object detection threshold for objects of the first object class in the second scene area.

A method for detecting objects in a scene captured by a camera, the method comprising:

• capturing video of the scene,
• segmenting a first image in the video into at least a first scene area and a second scene area, the first and second scene areas having properties such that ease or difficulty of detecting objects is expected to differ between the first and second scene areas,
• setting a first object detection threshold for the first scene area,
• detecting a first object in the first scene area in the first image, a first confidence value for the detection of the first object being above the first object detection threshold,
• in a plurality of images subsequent to the first image, tracking the first object as it moves into the second scene area,
• determining a second confidence value for a detection of the first object in the second scene area,
• setting a second object detection threshold for the second scene area such that the second confidence value for the detection of the first object is above the second object detection threshold, and
• in subsequent images, using the first object detection threshold for detecting objects in the first scene area and the second object detection threshold for detecting objects in the second scene area;
• the method further comprising performing a new segmentation of a later image subsequent to the first image based on a trigger event.

A method for detecting objects in a scene captured by a camera, the method comprising:

• capturing video of the scene,
• segmenting a first image in the video into at least a first scene area and a second scene area, the first and second scene areas having properties such that ease or difficulty of detecting objects is expected to differ between the first and second scene areas,
• setting a first object detection threshold for the first scene area,
• detecting a first object in the first scene area in the first image, a first confidence value for the detection of the first object being above the first object detection threshold,
• in a plurality of images subsequent to the first image, tracking the first object as it moves into the second scene area,
• determining a second confidence value for a detection of the first object in the second scene area,
• setting a second object detection threshold for the second scene area such that the second confidence value for the detection of the first object is above the second object detection threshold, and
• in subsequent images, using the first object detection threshold for detecting objects in the first scene area and the second object detection threshold for detecting objects in the second scene area;
• the method further comprising performing a new tracking of a later object in images subsequent to the first image based on a trigger event,
• determining an updated second confidence value for a detection of the later object in the second scene area,
• setting an updated second object detection threshold for the second scene area such that the updated second confidence value for the detection of the later object is above the updated second object detection threshold, and
• in images subsequent to the later image, using the first object detection threshold for detecting objects in the first scene area and the updated second object detection threshold for detecting objects in the second scene area.

A method for detecting objects in a scene captured by a camera, the method comprising:

• capturing video of the scene,
• segmenting a first image in the video into at least a first scene area and a second scene area, the first and second scene areas having properties such that ease or difficulty of detecting objects is expected to differ between the first and second scene areas,
• setting a first object detection threshold for the first scene area,
• detecting a first object in the first scene area in the first image, a first confidence value for the detection of the first object being above the first object detection threshold,
• in a plurality of images subsequent to the first image, tracking the first object as it moves into the second scene area,
• determining a second confidence value for a detection of the first object in the second scene area,
• setting a second object detection threshold for the second scene area such that the second confidence value for the detection of the first object is above the second object detection threshold, and
• in subsequent images, using the first object detection threshold for detecting objects in the first scene area and the second object detection threshold for detecting objects in the second scene area;
• wherein the step of segmenting is performed using a semantic segmentation algorithm.

An object detection system for detecting objects in a scene captured by a camera, the system comprising:

• a memory that stored the scene captured by the camera;
• and
• a processor, coupled to the memory, and configured to:
• capture video of the scene, the video comprising a sequence of captured images,
• segment a first captured image in the video into at least a first scene area and a second scene area based at least in part on expected differences in object detection conditions between the first scene area and the second scene area, wherein the first and second scene areas having properties such that ease or difficulty of detecting objects is expected to differ between the first and second scene areas,
• set thresholds for object detections in images in the video,
• detect objects in images in the video,
• determine confidence values for object detections, and
• track objects in images in the video,
• wherein processor is further configured to:
• set a first object detection threshold for the first scene area,
• detect a first object in the first scene area in the first captured image, a first confidence value for the detection of the first object being above the first object detection threshold,
• track the first object in a plurality of images subsequent to the first image, as it moves into the second scene area,
• determine a second confidence value for a detection of the first object in the second scene area,
• set a second object detection threshold for the second scene area such that the second confidence value for the detection of the first object is above the second object detection threshold, and
• use the first object detection threshold for detecting objects in the first scene area and the second object detection threshold for detecting objects in the second scene area in subsequent images.

An object detection system for detecting objects in a scene captured by a camera, the system comprising:

• a non-transitory computer-readable storage medium;
• and
• a processor, coupled to the non-transitory computer-readable storage medium, and configured to:
• capture video of the scene,
• segment a first image in the video into at least a first scene area and a second scene area, the first and second scene areas having properties such that ease or difficulty of detecting objects is expected to differ between the first and second scene areas,
• set thresholds for object detections in images in the video,
• detect objects in images in the video,
• determine confidence values for object detections, and track objects in images in the video,
• set a first object detection threshold for the first scene area,
• detect a first object in the first scene area in the first image, a first confidence value for the detection of the first object being above the first object detection threshold,
• track the first object in a plurality of images subsequent to the first image, as it moves into the second scene area,
• determine a second confidence value for a detection of the first object in the second scene area,
• set a second object detection threshold for the second scene area such that the second confidence value for the detection of the first object is above the second object detection threshold, and
• use the first object detection threshold for detecting objects in the first scene area and the second object detection threshold for detecting objects in the second scene area in subsequent images;
• wherein the processor is further configured to:
• determine an object class of detected objects, the first object being associated with a first object class, and
• set the first object detection threshold for objects of the first object class in the first scene area, and to set the second object detection threshold for objects of the first object class in the second scene area.

A non-transitory computer-readable storage medium comprising instructions which, when executed by a device with processing capability, cause the device to carry out a method for detecting objects in a scene captured by a camera, the method comprising:

• capturing video of the scene, the video comprising a sequence of captured images,
• segmenting a first captured image in the video into at least a first scene area and a second scene area based at least in part on expected differences in object detection conditions between the first scene area and the second scene area, wherein the first and second scene areas having properties such that ease or difficulty of detecting objects is expected to differ between the first and second scene areas,
• setting a first object detection threshold for the first scene area,
• detecting a first object in the first scene area in the first image, a first confidence value for the detection of the first object being above the first object detection threshold,
• in a plurality of captured images subsequent to the first image, tracking the first object as it moves into the second scene area,
• determining a second confidence value for a detection of the first object in the second scene area,
• setting a second object detection threshold for the second scene area such that the second confidence value for the detection of the first object is above the second object detection threshold, and
• in subsequent images, using the first object detection threshold for detecting objects in the first scene area and the second object detection threshold for detecting objects in the second scene area.