VEIL Event Detection

Event detection illustrates a powerful application of Veil's enhancements to traditional images processing.

An Event is a sequence of significant actions in the world.
An event template is defined using domain-specific terms in a high-level event language. This definitions establishes the criteria for detecting events.
Sequences of images matching the event criteria are located and the key elements in each image highlighted.

Loom uses concept definitions to create a domain-specific language for expressing the elements of an event. This allows a concise, high-level description of an event.

Example

In the example presented here, a Field Training Excercise is defined as a sequence of images showing a group of vehicles:

in a garrison area

traveling on a road in a convoy

exercising in a field

returning in a convoy.

Loom's query facility is used to locate sequences of images that satisfy the constraints of the event description. One such match, using images from the Radius Model Board 2 test set, is shown below:

Behind the Curtain

The event descriptors can be concisely expressed using a event template and the terminology from VEIL's domain model. The template

names the event

identifies the case roles (objects that participate in the event)

specifies components of the event (including conditions that must hold for that particular component)

general constraints that must hold across individual event components.

The descriptor for a field training exercise looks like this:

    (make-event :name 'field-training-exercise
		:case-roles '((armored-unit ?y))
		:components '((:scene ?s1 ?y (in-garrison ?y))
			      (:scene ?s2 ?y (convoy ?y))
			      (:scene ?s3 ?y (deployed-unit ?y))
			      (:scene ?s4 ?y (convoy ?y)))
		:constraints '((before+ ?s1 ?s2)
			       (before+ ?s2 ?s3)
			       (before+ ?s3 ?s4))))

This template is then used to generate a Loom query that retrieves a list of images along with the group that participates in the sequence:

    (retrieve (?S1 ?S2 ?S3 ?S4 ?Y)
	(and (within-context ?S1 (In-Garrison ?Y))
	     (within-context ?S2 (Convoy ?Y))
	     (within-context ?S3 (Deployed-Unit ?Y))
	     (within-context ?S4 (Convoy ?Y))
	     (before+ ?S1 ?S2)
	     (before+ ?S2 ?S3)
	     (before+ ?S3 ?S4))