Light field cameras are now commercially available and capture much more information about the rays of light reflected from the scene. This enables us to perform functions like changing the focus of an image after it has been captured.
Search Results for: light ray
Incandescent light sources emit a lot of infrared radiation which we cannot see but can sense as heat. Non-incandescent sources such as fluorescent lights, cathode ray tubes and LEDs have quite different spectrums. When light travels through an absorbing medium, such as the atmosphere or water, different wavelengths are absorbed differently and this alters its […]
Let’s look at how light rays reflected from an object can form an image. We use the simple geometry of a pinhole camera to describe how points in a three-dimensional scene are projected on to a two-dimensional image plane.
We can describe the relationship between a 3D world point and a 2D image plane point, both expressed in homogeneous coordinates, using a linear transformation – a 3×4 matrix. Then we can extend this to account for an image plane which is a regular grid of discrete pixels.
Let’s recap the important points from the topics we have covered about image formation and perspective projection.
Most objects reflect the light that falls on them and there are two aspects to this reflection. The first is geometric and concerned with the directions of the light rays: it can be specular reflection from a mirror like surface, or scattered Lambertian reflection from a matte surface. The second is the reflectance function which […]
The light we see is a mixture of different wavelengths in the visible region of the electromagnetic spectrum. The most common source of light is incandescence from a very hot body such as our sun or the filament of an old-fashioned light bulb. The spectrum, the amount of energy as a function wavelength, follows Planck’s […]
Many technologies have been developed to determine the 3D-structure of the world. RGBD sensors such as the Kinect use structured light, projecting a pattern of light onto the scene and observing how it is distorted. Time of flight sensors measure the time it takes for a pulse of light to travel from the camera to […]
Light entering our eyes stimulates the photoreceptor cells in the retina of our eye: color sensitive cone cells that we use in normal lighting conditions and monochromatic rod cells we use in low light. The density of these cells varies across the retina, it is high in the fovea, low in the peripheral vision region […]
Humans have long been fascinated with seeing images and movies in ‘3D’. Let’s look at how human stereo vision works and some of the technologies used to present images to our eyes in ‘3D’.