# Frequent question: What is horizontal and vertical illuminance?

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The horizontal measurement is known as the horizontal illuminance and is the amount of light that lands on a horizontal surface, such as a tabletop. The vertical measurement is know as the vertical illuminance and is the amount of light that lands on a vertical surface, such as a wall.

## What is horizontal illuminance?

Horizontal Illuminace is the amount of light falling on a horizontal activity plane (also called workplane). Horizontal Illuminance in a Conference Room with electric lighting. … Notice the footcandle levels are highest in the center of the space, under the central luminaires.

## How is vertical illuminance measured?

For some applications including museums or retail spaces, vertical illuminance is also of interest within the space. Divide the vertical surfaces in equally sized square sections and measure and record the illuminance at the grid intersections.

## How do you calculate horizontal illuminance?

Horizontal Illuminance – Horizontal illuminance at a point is a measure of the lumens incident on the pavement divided by the area. The units are lumens per square meter (lux). Illuminance is not impacted by the pavement’s surface type or the angle of observation.

## What is perpendicular illuminance?

Perpendicular illuminance: The perpendicular light which strikes on a horizontal surface. Perpendicular illuminance(Adaptive): The perpendicular light which strikes on a horizontal surface.

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## What is vertical illuminance?

In other words, vertical illuminance can be defined as the measure of light perception by camera and our eyes when reflected off a surface. It is measured in the unit “lux” and mostly used for televised games and events.

## What is lighting uniformity ratio?

Uniformity is the ratio of the minimum lighting level to the average lighting level in a specified area. It’s a quality parameter for the overall illuminance distribution.

## How do you perform a lux test?

Test how lux readings change with distance from a fixed light source. For example, stand directly under a ceiling light, hold your phone with the screen facing up, and move the phone up and down. Alternatively hold the phone sideways and aim it toward a floor lamp as you walk closer to and farther away from the lamp.

## What do you mean by illuminance?

In photometry, illuminance is the total luminous flux incident on a surface, per unit area. It is a measure of how much the incident light illuminates the surface, wavelength-weighted by the luminosity function to correlate with human brightness perception.

## What is the formula for illuminance?

The equation of the illuminance, E, of a small light source is E = P/ 4(pie)d^2, where P is the luminous flux (in lumens, lm) of the source and d is its distance from the surface.

## What is the formula of illumination?

The luminous flux falling on the area dA from a source of intensity I is given by dF = IdA cos φ/r2, as shown in the diagram at the left. This follows directly from the definition of I as luminous flux per unit solid angle and the definition of solid angle.