Luxmeters can have different scales depending on the amount of light to be measured, in order to be able to have a more exact precision in case of stronger or weaker luminosity.

Diffused lightexamples

Before we look at how light is measured, let's look at a little more definition of this concept. Light is a form of electromagnetic radiation capable of exciting the retina of the human eye to produce a visual sensation.

White light is therefore understood as light that contains all the colours of the visible spectrum, which can be classified as follows:

Diffused lightphotography examples

At each end of the visible spectrum - and already imperceptible to the human eye - are the wavelengths corresponding to infrared light - 750 nm - and ultraviolet light - below 400 nm.

Diffuselightbulb

Radiation energy in the form of waves is only perceptible when it interacts on a medium with a given direction. This transfer of energy from one body to another is what we call radiation.

Visible light or the visible spectrum is the region of the electromagnetic spectrum that can be perceived by the human eye and corresponds to wavelengths between 380 and 750 nanometres.

The human eye is sensitive to a very wide range of light intensities, but at low levels of illumination, it can lose the ability to differentiate some details.

Diffused lightCeiling

The example WebGL program above was based on a “point light source”. If you had a different type of light source, such as a sun light source, the shader programs would have to be changed because the definition of your light source would change, but the fundamental math would be the same.

The operation is very simple, but before measuring the light it is advisable to take into account the preconditions. Thus, the distance and the angle between the luxmeter and the object to be measured should be fixed in order to obtain results with high reproducibility.

The diagram to the right labels the pieces needed to calculate diffuse reflection. We need to calculate the angle between the vertex’s normal vector and a vector pointing at the light source from the vertex. This angle is labeled “theta” in the diagram.

In other words, it is a measuring device that allows us to know how much light or luminosity there is in an environment with which light is perceived by the human eye.

In 1672, the scientist Isaac Newton demonstrated that sunlight, white light, was not pure as previously believed, but was composed of a mixture of different colours. He refracted white light through a prism and broke it down into the basic colours of the visible spectrum.

Diffused lightarchitecture

What is diffused lightfor plants

Examine the plot of a cosine curve to the right. Notice that when the angle is zero, the cosine of zero is 1.0. As the angle increases, the cosine of the angle curves to zero. When the angle is 90 degrees, the cosine of 90 is 0.0. This is lambert’s cosine law. The cosine values are treated as percentages of color. When the angle is zero, cos(0) is 1.0, and you get 100% color. When the angle is 90 degrees, cos(90) is zero and you get 0% color. When the angle becomes greater than 90 or less than -90 the cosine goes negative. This is an indication that the front side of the triangle is pointing away from the light source. You can’t have a negative percentage of light, so we clamp the cosine of the angle to values between 0.0 and 1.0.

Diffusedlighting interior design

Through the sensor inside the lux meter we can obtain, at a selected point, the value of the light intensity. In this way we can know if the light, artificial or natural, captured by the meter meets or does not meet the minimum values for its conversion to be adequate.

Diffused lightlamp

If both v0 and v1 are normal vectors that have a length of 1, the dot product gives the cosine of the angle without any division.

Light that directly strikes an object and then reflects in all directions is called “diffuse” light. The amount of light reflection is determined by the angle between the light ray and the surface normal vector. In Physics, Lambert’s cosine law provides an equation for calculating diffuse color.

For this reason, it is very important to be able to measure the light levels correctly according to the use that our space will have in order to have a correct illumination. From Faro Barcelona we want to give you some tips so that you can measure light correctly and be efficient in the expected result.

The luxmeter is a tool that helps to measure the lighting conditions of an interior space. As its name indicates, the luxmeter's unit of measurement is the lux.

Light is the form of energy that illuminates things and makes them visible. It is an electromagnetic wave that can be perceived by the human eye and whose frequency determines its colour.

As you experiment with the demonstration program, please make sure you observe the following characteristics of diffuse reflection.

It can be shown that the dot product of two vectors is equal to the cosine of the angle between the two vectors divided by the length of the two vectors. In code format, this means that:

The dot product of two vectors is defined as the sum of the products of their associated terms. 3D vectors are normally stored as arrays, where (v[0], v[1], v[2]) is the values of the vector. Therefore, the dot product of vectors v0 and v1 is:

To perform diffuse lighting calculations each vertex that defines a triangle must have an associated normal vector. The normal vector defines a direction that is projecting out from the front side of the triangle. The normal vector defines how light will reflect off of a surface defined at the vertex. The normal vector may be 90 degrees to the surface of the triangle, or it might be at some other angle to simulate a curved surface.

In order to measure light, according to the International System of Measurement, we have to base ourselves on three specific aspects and on the distance of the set of luminous rays from the same origin.