Destructive interference occurs when waves meet out of phase, their amplitudes cancel out, creating a wave with a smaller or even zero amplitude.

Multi spectral imagingcamera

Wave superposition is the phenomenon where two or more waves combine to form a resultant wave. The resultant wave's amplitude at any point is the sum of the amplitudes of the individual waves at that point.

Multispectralimagingskin

Wave behaviour is a crucial aspect of Year 11 HSC Physics. It encompasses several phenomena, including reflection, refraction, diffraction, and wave superposition. Understanding these principles can give us insights into everything from the way light interacts with materials to the propagation of sound waves.

Vice versa, if the refractive index of the second medium is smaller than the first medium, the wave would bend away from the normal as it travels through the medium.

Multispectralimagingsatellites

When a wave passes from one medium to another with a different refractive index, its speed changes. This change in speed leads to refraction, or the bending of the wave. But what happens to the frequency and wavelength of the wave during this process?

Difference between multispectral and hyperspectral remote sensing

Snell's Law provides a mathematical way to predict the angle of refraction based on the medium's refractive index. It's expressed as:

The angle of incidence (the angle between the incoming wave and the normal of the surface) is equal to the angle of reflection (the angle between the reflected wave and the normal). The normal is a perpendicular line drawn from the surface.

Multispectralimagingin agriculture

If the refractive index of the second medium is greater than the first medium, then the angle of refraction would be smaller than the angle of incidence. This means the wave would bend towards the normal as it travels through the medium.

The wavelength of the wave changes in proportion to the speed of the wave as it enters a new medium. If the wave slows down (as it does when moving from a medium with a lower refractive index to one with a higher refractive index), the wavelength decreases. Conversely, if the wave speeds up (when moving from a higher to a lower refractive index), the wavelength increases.

Multispectralimagingarchaeology

Hyperspectral vs multispectral

Images of an object in a series of spectral bands are acquired, and once the images are registered and calibrated, they are uploaded into the reflectance image cube. This represents the pixels of each image in the X and Y axes, while the Z dimension denotes the wavelength of each spectral image. From the cube, it is then possible to reconstruct the reflectance spectrum for each pixel of the image. MSI analysis is based on the same concepts of Reflectance Spectroscopy. Still, MSI has the added advantage that the pigments can be identified and mapped remotely on large areas rather than just a single spot.

Constructive interference occurs when waves meet in phase, their amplitudes add together, creating a wave with a larger amplitude.

Multispectral Imaging (MSI) maps and tentatively identifies pigments and retouchings on works of art. It is also used to visually enhance old and faded documents. Conservators can use this technique to distinguish original sections from inpaints and to select the proper conservation procedures.

When waves pass through a narrow slit, they spread out in a pattern that can be described using the wavelength and the size of the opening. As the size of the opening becomes smaller, the degree of diffraction increases.

Reflection is the phenomenon where waves bounce off a surface, reversing their direction. This behaviour is common in light and sound waves and can be observed in everyday life.

Where `n_1` and `n_2` are the refractive indices of the two media, and `\theta_1` and `\theta_2` are the angles of incidence and refraction, respectively.

Multispectral images in Remote sensing

Refraction changes the speed of a wave as it passes from one medium into another, but it does so without altering the wave's frequency.

The frequency of a wave is determined by the source of the wave and remains constant as the wave passes through different media. Since the frequency doesn't change, any alteration in speed must be compensated for by a corresponding change in wavelength.