Prior to the background of the invention being set forth, it may be helpful to set forth definitions of certain terms that will be used hereinafter.
The term ‘sensing device’ as used herein is broadly defined as any combination of one or more sensors that are configured to capture 2D images of a scene. The sensing device may include any type of passive camera or sensor array that can capture radiation and derive an image out of it (examples may include: visible light, IR, ultra sound, radar sensor, and the like).
The term ‘shadow’ as used herein is broadly defined as a region where radiation from a radiation source (such a light source) is obstructed by an opaque (in the appropriate wavelengths) object. The shadow occupies all of the three-dimensional volume behind an object with light or radiation in front of it. The cross-section of a shadow is a two-dimensional silhouette, or a reverse projection of the object blocking the radiation or light.
The term ‘point light source’ or ‘point radiation source’ as used herein is defined as a light source or a radiation source that only casts a simple shadow, called an “umbra”.
The term ‘non-point light source’ or ‘extended light source’ or ‘extended radiation source’ as used herein is defined as a radiation or light source whose shadow is divided into the umbra, penumbra and antumbra. The wider the light source or radiation source, the more blurred the shadow becomes. If two penumbras overlap, the shadows appear to attract and merge.
The term ‘ambient light’ or ‘ambient radiation’ as used herein is defined as light or radiation that is diffused beyond a certain level so that the outlines of shadows are soft and indistinct or completely non-existent. For example, the lighting of an overcast sky produces few visible shadows.
The term ‘distinct light source’ or ‘distinct radiation source’ as used herein in the context of the application is a residual definition of the ambient light discussed above. Generally speaking, a distinct radiation light source will cause objects in a scene to cast shadows having distinct outlines. The outlines of the shadow zones can be found by tracing the rays of light emitted by the outermost regions of the extended light source. If there are multiple light sources, there will be multiple shadows, with overlapping parts darker, and various combinations of brightness levels or even colors.
One of the challenges of computer vision is to detect the presence, and obtain knowledge about distinct radiation or light sources (as opposed to ambient light or ambient radiation) in a scene. The importance of radiation light source analysis is crucial in some use cases such as augmented reality applications in which virtual objects are inserted into the scene and it is essential that the virtual objects will be affected by the lighting conditions as any other real object present in the scene. Additionally, it is also important for enhancing the illusion notion of the viewer, that the virtual objects will cast shadows in a similar way to real objects, given the specified light or radiation conditions.
It would be therefore advantageous to suggest some logic or a flow that will enable a computerized vision system to determine the properties of all distinct light or radiation sources that affect a specific scene that is being captured and analyzed.