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Calculations - Roadway - Concepts

The Calculation Points - Roadway command allows you to specify several lighting metrics associated with roadway lighting applications in a straight segment of roadway. The resulting calculations are calculated based on the user’s selection of the roadway Standard to which they will be designing. AGi32 includes default input parameters for grid placement and point spacing based on ten roadway Standards in use around the world:

- The IES RP-8 method uses the algorithms in IES RP-8-00 (reaffirmed in 2005) and RP-8-14.
- The IES RP-22 method uses the algorithms in IES RP-22-11.
- The CIE method uses the algorithms in CIE 140-2000. (CIE 115-2010 uses same calculation methods)
- The ABNT method uses the algorithms in NBR5101-2012.
- The ABNT Compact version uses the algorithms in NBR5101-2012(C).
- The Australia and New Zealand methods use the algorithms in Australia/New Zealand Standard 1158.2-2005.
- The BSEN method uses the algorithms in the 13201-3.2003 document. (BSEN 5489-1:2013 uses same calculation methods)

This table shows the calculation metrics that are defined in each Standard:

IES RP-8-14 | IES RP-8-2000 | IES RP-22-2011 | CIE 140-2000 | BSEN 13201-3 .2003 | ABNT NBR5101-2012 | ABNT NBR5101-2012(C) | Australia 1158.2-2005 | New Zealand 1158.2-2005 | |
---|---|---|---|---|---|---|---|---|---|

Pavement Luminance | X | X | X | X | X | X | X | X | |

Illuminance | X | X | X | X | X | X | X | X | X |

Veiling Luminance | X | X | X | ||||||

Visibility Level (STV) | X | X | |||||||

Longitudinal Uniformity | X | X | X | X | X | ||||

Vertical Illuminance | X | ||||||||

Semi-cylindrical Illuminance | X | X | X | ||||||

Hemispherical Illuminance | X | ||||||||

Surround Illuminance | X | X | X | X | X | ||||

Veiling Luminance w/TI | X | X | X | X | X |

- Files with Roadway Calculation grids created in version 2.1 or later will not open in earlier versions of AGi32. Files created in version 2.04 or earlier can be opened in version 2.1 or later, but the calculation grids are converted to a single Illuminance grid that can be edited in the later versions. Converted grids are assigned to a '_Converted-Illuminance Only' Standard. Converted grids must be edited, applying an actual Roadway Standard and selecting additional calculation metrics as applicable. A message is displayed when opening an AGI file with older-version roadway grids.
- Roadway calculations do not consider daylight contributions at this time.

Roadway Luminance Calculations With Obstructive and/or Reflective Surfaces

**Tunnels:** In Full Radiosity calculations, the Roadway Luminance calculation can take
reflective or obstructive entities around or within the luminance grid
into account, per IES Recommended Practice for Tunnel Lighting, RP-22, recommendations. This is also true for the
associated illuminance and veiling luminance calculations.

**Consideration of Surfaces in Roadway Calculations: **

- Surfaces that are to be included in Full Radiosity Calculations must be assigned a special surface type
(Roadway Contributor or Roadway Pavement) if reflected light is to be considered. Surfaces that are
*not*one of the two Roadway surface types will obstruct light and will reflect light to the environment but*not*to the roadway calculation grids. If the Full Radiosity Calculation command is initiated with non-roadway surfaces present, a Warning will be displayed, showing which surfaces comply and which do not, and offering the option to continue or abort the calculation. - Surfaces may be composed of 3D Entities imported into AGi32 or made with AGi32's modeling commands. In either case, the existing surfaces may be modified in AGi32 with the Edit Object command (select the entity and then select the Surface Edit button in the Edit dialog), or by using the Surface Edit command and selecting the entities.

More information is available in the Roadway Luminance Calculations With Reflective Surfaces topic.

Technical Details

The Roadway Optimizer tool and Roadway Luminance command provide assistance in computing calculations for straight segments of roadways using IES, CIE, BSEN, CIE-Australia, or CIE-New Zealand methods. Some of the criteria and recommended values are provided here.

IES RP-8-00 and RP-8-14

AGi32 creates the calculation grids used to calculate Pavement Luminance, Illuminance, and Veiling Luminance per the last two revisions of RP-8 (RP-8-00, displayed as RP-8-2000, and RP-8-14).

**Note:**RP-8-2000 and RP-8-14 are functionally the same, as far observer location, point spacing, etc. RP-8-2000 remains in the Roadway Standards list for backwards compatibility with older files.

Average Pavement Luminance (L_{avg})
- Luminance on the pavement is
based on the quantity and direction of light, observer location, and the
pavement reflectance characteristics. The overall average luminance of the road surface as observed from a
specific point in cd/m^{2}. Metric units are used regardless of current
settings. Observer position is 1.45 meters above the pavement surface and
83.07 meters back from each computation point along a longitudinal line
parallel to the direction of travel. Observer line of sight is 1 degree
below horizontal. Observer position changes relative to the curb line
to align with each row of calculation points. A Roadway Luminance grid represents the calculation points for a single
directional flow of traffic. To consider the entire roadway, a calculation
grid should be created for each direction of traffic flow. The directional flow
of traffic is determined by the specified order of the curb points defining the
length of the roadway. Traffic flows in the direction of first point
to second point. The third point defines the width of the roadway
from curb to curb in one direction of traffic flow.

**Illuminance -** Illuminance is a measure of the lumens incident on the pavement divided by the area. The units are lumens per square foot (footcandles) or lumens per square meter (lux). Illuminance is not impacted by the pavement's surface type or the angle of
observation.

Veiling Luminance (L_{v}) - A measure
of disability glare, veiling luminance is a luminance superimposed over
the eye's retinal image that is produced by stray light within the eye. In the
IES method, L_{v} is computed at the same points as the pavement luminance
with the observer 83.07 meters back from each computation point. Observer height is 1.45 m above the road surface, with
line of sight 1 degree below horizontal.

Veiling Luminance ratio - The
IES method uses the maximum value of Veiling Luminance (L_{v,max}) divided by
the Average Pavement Luminance (L_{avg}) as a measure of the disability glare
produced by a lighting system.

Weighted Average VL (STV) – A measure of the visibility of small targets in the roadway considering the target luminance, veiling luminance and the background pavement luminance against which they are seen. The weighted average of all Visibility Levels (STV) is given. An Visibility Level grid may be included in the calculated results. It is recommended that this grid be examined, as it provides information about contrast bands . When considering Visibility Level and STV, designs are created that produce negative and positive contrast, all positive contrast, and all negative contrast. The weighted average of the calculated Visibility Levels is displayed as the STV.

IES RP-22-11

AGi32 creates the calculation grids used to calculate Pavement Illuminance, Luminance and Veiling Luminance per the latest revision of RP-22 (RP-22-11, displayed as RP-22-2011).

Average Pavement Luminance (L_{avg})
- Luminance on the pavement is
based on the quantity and direction of light, observer location, and the
pavement reflectance characteristics. The overall average luminance of the road surface as observed from a
specific point in cd/m^{2}. Metric units are used regardless of current
settings. Observer position is 1.45 meters above the pavement surface and
83.07 meters back from each computation point along a longitudinal line
parallel to the direction of travel. Observer line of sight is 1 degree
below horizontal. Observer position changes relative to the curb line
to align with each row of calculation points. A Roadway Luminance grid represents the calculation points for a single
directional flow of traffic. To consider the entire roadway, a calculation
grid should be created for each direction of traffic flow. The directional flow
of traffic is determined by the specified order of the curb points defining the
length of the roadway. Traffic flows in the direction of first point
to second point. The third point defines the width of the roadway
from curb to curb in one direction of traffic flow.

**Illuminance -** Illuminance is a measure of the lumens incident on the pavement divided by the area. The units are lumens per square foot (footcandles) or lumens per square meter (lux). Illuminance is not impacted by the pavement's surface type or the angle of
observation.

Veiling Luminance (L_{v}) - A measure
of disability glare, veiling luminance is a luminance superimposed over
the eye's retinal image that is produced by stray light within the eye. In the
IES method, L_{v} is computed at the same points as the pavement luminance
with the observer 83.07 meters back from each computation point. Observer height is 1.45 m above the road surface, with
line of sight 1 degree below horizontal.

Veiling Luminance ratio - The
IES method uses the maximum value of Veiling Luminance (L_{v,max}) divided by
the Average Pavement Luminance (L_{avg}) as a measure of the disability glare
produced by a lighting system.

CIE 140-2000

**Note:**CIE 115-2010 uses the same calculation methods, including observer location, point spacing, etc.

A**verage
Pavement Luminance** - The overall average luminance of the road
surface as observed from a specific point in cd/m_{2}. Metric units are
used, regardless of current settings. By default, observer position is
1/4 roadway width inset from the curb, 1.5 m above the pavement surface
and 60m back from the first lateral row of computation points in the grid. Line of sight is 0.5 - 1.5
degrees below horizontal, depending on the distance to the points. Observer position is static relative to the curb
line.

**Illuminance -** Illuminance 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.

Longitudinal Uniformity - The ratio of minimum to maximum pavement luminance, illuminance or veiling luminance is taken along each longitudinal line of computation points. The worst-case ratio is displayed as the Longitudinal Uniformity Ratio. For the CIE method, an additional grid of pavement luminance points is computed, with observer position centered in the middle of each lane, 60m back from the first lateral row of computation points in the grid, and viewing along the line of points in that lane.

Surround Ratio - This is a ratio of the average horizontal illuminance on the two longitudinal strips each adjacent to the two edges of the carriageway (the surround illuminance), divided by the average horizontal illuminance on two longitudinal strips each adjacent to the two edges of the carriageway, but lying on the carriageway. The width of all four strips shall be the same, and equal to 5m, or half the width of the carriageway, or the width of the unobstructed strip lying off the carriageway, whichever is the least. For dual carriageways, both carriageways together are treated as a single carriageway unless they are separated by more than 10m.

Veiling Luminance (L_{v}) - A measure
of disability glare, Veiling Luminance is a luminance superimposed over
the eye's retinal image produced by stray light within the eye. In the
CIE method, L_{v} is computed along a single row of calculation points directly
in front of the observer position. By default, the distance of the observer to
the first lateral row of computation points in the grid is 2.75 x (mounting ht - 1.5) meters and 1/4 road width from the curb line. 0.5 - 1.5
degrees below horizontal, depending on the distance to the points.
The maximum value of L_{v} is used to compute the relative Threshold Increment
(TI). NOTE: The CIE 140-2000 method of calculating veiling luminance is *per 1000 lamp lumens*. This generates rather small values. Therefore, it is recommended that if you are calculating veiling luminance with the CIE standard, you first open the Units dialog (bottom toolbar in Model Mode or top toolbar in Roadway Optimizer) and set the Number of Decimals value to 2 or 3. This will help to avoid generating all zeros.

Relative Threshold Increment
(TI) - A measure of the effect of disability glare produced by the lighting
system. Threshold Increment is intended to yield the percentage increase
in the luminance of the road's surface required to render an object just
visible (threshold of visibility) under the proposed lighting system (glare
present) as compared to the luminance required to render the object just
visible in the absence of glare. *Important note:* Threshold Increment is calculated differently here than in AS4282-1997 or CIE 150:2003.

**Note:**BSEN 5489-1:2013 uses the same calculation methods, including observer location, point spacing, etc.

A**verage
Pavement Luminance** - The overall average luminance of the road
surface as observed from a specific point in cd/m_{2}. Metric units are
used, regardless of current settings. By default, observer position is
1/4 roadway width inset from the curb, 1.5 m above the pavement surface
and 60m back from the first lateral row of computation points in the grid. Line of sight is 0.5 - 1.5
degrees below horizontal, depending on the distance to the points. Observer position is static relative to the curb
line.

**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.

Longitudinal Uniformity - The ratio of minimum to maximum pavement luminance, illuminance or veiling luminance is taken along each longitudinal line of computation points. The worst-case ratio is displayed as the Longitudinal Uniformity Ratio. For the CIE method, an additional grid of pavement luminance points is computed, with observer position centered in the middle of each lane, 60m back from the first lateral row of computation points in the grid, and viewing along the line of points in that lane.

V**ertical Illuminance** - Measured in lux, vertical illuminance at a point is calculated on a plane 1.5 m above the surface of the road. The grid is located on the same points as the roadway luminance grid.

**Semi-cylindrical Illuminance -** Measured in lux, semi-cylindrical illuminance at a point could be considered a type of vertical illuminance, but its calculated value varies with the direction of interest. It is calculated at 1.5 meters above the road surface and on a half cylinder whose front is lined up parallel to the main directions of pedestrian movement, which for a road are usually longitudinal. The grid is located on the same points as the roadway luminance grid.

Hemispherical Illuminance - Measured in lux, hemispherical illuminance at a point is calculated at ground level on the road surface. Its formula is similar to the formula for horizontal illuminance, but differs from it in the way that the angle of incidence is considered.

Surround Ratio - This is a ratio of the average horizontal illuminance on the two longitudinal strips each adjacent to the two edges of the carriageway (the surround illuminance), divided by the average horizontal illuminance on two longitudinal strips each adjacent to the two edges of the carriageway, but lying on the carriageway. The width of all four strips shall be the same, and equal to 5m, or half the width of the carriageway, or the width of the unobstructed strip lying off the carriageway, whichever is the least. For dual carriageways, both carriageways together are treated as a single carriageway unless they are separated by more than 10m.

Veiling Luminance (L_{v}) - A measure
of disability glare, Veiling Luminance is a luminance superimposed over
the eye's retinal image produced by stray light within the eye. In the
BSEN method, L_{v} is computed along a single row of calculation points directly
in front of the observer position. By default, the distance of the observer to
the first lateral row of computation points in the grid is 2.75 x (mounting ht - 1.5) meters and 1/4 road width from the curb line. 0.5 - 1.5
degrees below horizontal, depending on the distance to the points.
The maximum value of L_{v} is used to compute the relative Threshold Increment
(TI).

Relative Threshold Increment
(TI) - A measure of the effect of disability glare produced by the lighting
system. Threshold Increment is intended to yield the percentage increase
in the luminance of the road's surface required to render an object just
visible (threshold of visibility) under the proposed lighting system (glare
present) as compared to the luminance required to render the object just
visible in the absence of glare.* Important note:* Threshold Increment is calculated differently here than in AS4282-1997 or CIE 150:2003.

ABNT NBR5101-2012

A**verage
Pavement Luminance** - The overall average luminance of the road
surface as observed from a specific point in cd/m_{2}. Metric units are
used, regardless of current settings. By default, observer position is
1/4 roadway width inset from the curb, 1.5 m above the pavement surface
and 60m back from the first lateral row of computation points in the grid. Line of sight is 0.5 - 1.5
degrees below horizontal, depending on the distance to the points. Observer position is static relative to the curb
line.

**Illuminance -** Illuminance 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.

Longitudinal Uniformity - The ratio of minimum to maximum pavement luminance, illuminance or veiling luminance is taken along each longitudinal line of computation points. The worst-case ratio is displayed as the Longitudinal Uniformity Ratio. For the CIE method, an additional grid of pavement luminance points is computed, with observer position centered in the middle of each lane, 60m back from the first lateral row of computation points in the grid, and viewing along the line of points in that lane.

**Semi-cylindrical Illuminance -** Measured in lux, semi-cylindrical illuminance at a point could be considered a type of vertical illuminance, but its calculated value varies with the direction of interest. It is calculated at 1.5 meters above the road surface and on a half cylinder whose front is lined up parallel to the main directions of pedestrian movement, which for a road are usually longitudinal. The grid is located on the same points as the roadway luminance grid.

Surround Ratio - This is a ratio of the average horizontal illuminance on the two longitudinal strips each adjacent to the two edges of the carriageway (the surround illuminance), divided by the average horizontal illuminance on two longitudinal strips each adjacent to the two edges of the carriageway, but lying on the carriageway. The width of all four strips shall be the same, and equal to 5m, or half the width of the carriageway, or the width of the unobstructed strip lying off the carriageway, whichever is the least. For dual carriageways, both carriageways together are treated as a single carriageway unless they are separated by more than 10m.

Veiling Luminance (L_{v}) - A measure
of disability glare, Veiling Luminance is a luminance superimposed over
the eye's retinal image produced by stray light within the eye. In the
CIE method, L_{v} is computed along a single row of calculation points directly
in front of the observer position. By default, the distance of the observer to
the first lateral row of computation points in the grid is 2.75 x (mounting ht - 1.5) meters and 1/4 road width from the curb line. 0.5 - 1.5
degrees below horizontal, depending on the distance to the points.
The maximum value of L_{v} is used to compute the relative Threshold Increment
(TI). NOTE: The NBR5101-2012 method of calculating veiling luminance is *per 1000 lamp lumens*. This generates rather small values. Therefore, it is recommended that if you are calculating veiling luminance with the CIE standard, you first open the Units dialog (bottom toolbar in Model Mode or top toolbar in Roadway Optimizer) and set the Number of Decimals value to 2 or 3. This will help to avoid generating all zeros.

Relative Threshold Increment (TI) - A measure of the effect of disability glare produced by the lighting system. Threshold Increment is intended to yield the percentage increase in the luminance of the road's surface required to render an object just visible (threshold of visibility) under the proposed lighting system (glare present) as compared to the luminance required to render the object just visible in the absence of glare.

Australia Standard 1158.2- 2005

**verage
Pavement Luminance** - The overall average luminance of the road
surface as observed from a specific point in cd/m_{2}. Metric units are
used, regardless of current settings. By default, observer position is
1/4 roadway width inset from the curb, 1.5 m above the pavement surface
and 60m back from the first lateral row of computation points in the grid. Line of sight is 0.5 - 1.5
degrees below horizontal, depending on the distance to the points. Observer position is static relative to the curb
line.

**Illuminance -** Illuminance 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.

Surround Ratio - This is a ratio of the average horizontal illuminance on the two longitudinal strips each adjacent to the two edges of the carriageway (the surround illuminance), divided by the average horizontal illuminance on two longitudinal strips each adjacent to the two edges of the carriageway, but lying on the carriageway. The width of all four strips shall be the same, and equal to 3 meters. The grid shall be placed at the same distance as the luminance calculation field.

Veiling Luminance (L_{v}) - A measure
of disability glare, Veiling Luminance is a luminance superimposed over
the eye's retinal image produced by stray light within the eye. In the
BSEN method, L_{v} is computed along a single row of calculation points directly
in front of the observer position. By default, the distance of the observer to
the first lateral row of computation points in the grid is 2.75 x (mounting ht - 1.5) meters and 1/4 road width from the curb line. 0.5 - 1.5
degrees below horizontal, depending on the distance to the points.
The maximum value of L_{v} is used to compute the relative Threshold Increment
(TI).

Relative Threshold Increment
(TI) - A measure of the effect of disability glare produced by the lighting
system. Threshold Increment is intended to yield the percentage increase
in the luminance of the road's surface required to render an object just
visible (threshold of visibility) under the proposed lighting system (glare
present) as compared to the luminance required to render the object just
visible in the absence of glare. *Important note:* Threshold Increment is calculated differently here than in AS4282-1997 or CIE 150:2003.

Australia Standard 1158.2- 2005 - SAASTAN

The SAASTAN software calculates some of the Australian metrics differently than Australian Standard 1158.2-2005 defines. Specifically, the luminaire cycles that will contribute to the calculation grid points are different in SAASTAN from what is defined in AS 1158.2-2005, and the position of the observer for the veiling luminance calculations is also different. These differences can lead to different calculated values for any or all of the roadway metrics.

AGi32 includes AS 1158.2-2005 - SAASTAN as a selectable "standard" for those projects that must be calculated by SAASTAN methods rather than by Standard 1158.2-2005.

New Zealand Standard 1158.2- 2005

**verage
Pavement Luminance** - The overall average luminance of the road
surface as observed from a specific point in cd/m_{2}. Metric units are
used, regardless of current settings. By default, observer position is
1/4 roadway width inset from the curb, 1.5 m above the pavement surface
and 60m back from the first lateral row of computation points in the grid. Line of sight is 0.5 - 1.5
degrees below horizontal, depending on the distance to the points. Observer position is static relative to the curb
line.

**Illuminance -** Illuminance 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.

Surround Ratio - This is a ratio of the average horizontal illuminance on the two longitudinal strips each adjacent to the two edges of the carriageway (the surround illuminance), divided by the average horizontal illuminance on two longitudinal strips each adjacent to the two edges of the carriageway, but lying on the carriageway. The width of all four strips shall be the same, and equal to 3 meters.The grid shall be placed at the same distance as the luminance calculation field.

Veiling Luminance (L_{v}) - A measure
of disability glare, Veiling Luminance is a luminance superimposed over
the eye's retinal image produced by stray light within the eye. In the
BSEN method, L_{v} is computed along a single row of calculation points directly
in front of the observer position. By default, the distance of the observer to
the first lateral row of computation points in the grid is 2.75 x (mounting ht - 1.5) meters and 1/4 road width from the curb line. 0.5 - 1.5
degrees below horizontal, depending on the distance to the points.
The maximum value of L_{v} is used to compute the relative Threshold Increment
(TI).

*Important note:* Threshold Increment is calculated differently here than in AS4282-1997 or CIE 150:2003.

A roadway's reflective characteristics are defined by its physical surface properties. Sufficient data has been collected on the reflectance characteristics of different pavement types to allow them to be described by reflectance tables or "R" tables.

Several typical roadway pavements are provided for your use, as defined in the R-Table pull-down menu.

R-Table |
Q |
Description |
---|---|---|

C1 | 0.10 | CIE C1 - Concrete |

C2 | 0.07 | CIE C2 - Asphalt |

N1 | 0.10 | CIE Class = 1, Very Diffuse |

N2 | 0.07 | CIE Class = 1, Concrete |

N3 | 0.07 | CIE Class = 3, Asphalt |

N4 | 0.08 | CIE Class = 4, Glossy Asphalt |

NZN2 | 0.09 | New Zealand - Glossy Polished Asphaltic Surface |

NZN4 | 0.09 | New Zealand - Diffuse Chip Seal Surface |

R1 |
0.10 |
IES RP-8 - Mostly diffuse reflectance properties characteristic of Portland cement or asphalt surface with a minimum of 15% of the aggregates composed of artificial brightener aggregates. |

R2 |
0.07 |
IES RP-8 - A combination of diffuse and specular reflectances characteristic of asphalt surfaces with aggregate composed of a minimum of 60% gravel of size greater than 10 mm. Also asphalt surfaces composed of 10% - 15% artificial brightener in aggregate mix. |

R3 |
0.07 |
IES RP-8 - Slightly specular reflectance typical of asphalt surfaces with dark aggregates, rough texture and some months of use. This surface is common in the United States. |

R4 |
0.08 |
IES RP-8 - Mostly specular surface typical of very smooth asphalt texture. |

UKPA |
0.05 |
UK - Porous Asphalt |

W1 | 0.11 | CIE W1 - Wet Road Surface |

W2 | 0.15 | CIE W2 - Wet Road Surface |

W3 | 0.21 | CIE W3 - Wet Road Surface |

W4 | 0.25 | CIE W4 - Wet Road Surface |

ZOAB |
0.10 |
CIE Class = 2, Dutch Porous Asphalt |

Q_{0} is a value that is related to the overall reflectance of the pavement by a factor of π: Q_{0} x π = overall reflectance.

Additional R-tables can be added to AGi32 easily. Please contact Lighting Analysts for details.

Note: If a user creates an R-Table and then uses it in an AGi32 calculation, that R-Table is not included with the saved AGI file. Therefore, if that AGI file is transferred to another computer, AGi32 will not find the custom R-Table and will use the default (R3). The custom R-Table would have to be added to the new computer in the ProgramData folder.

Illuminance vs Luminance

RP-8-14's criteria are luminance based, except for curvy or hilly roads or streets. In those cases, the criteria are illuminance based.

The average pavement luminance is influenced by three factors: the quantity and direction of light, the observer location, and the reflective characteristics of the pavement. Illuminance, on the other hand, measures the light incident on the pavement surface; observer direction and pavement reflectance are irrelevant.

While there is certainly a strong relationship between luminance and illuminance, it is possible to meet the Illuminance criteria, yet be substantially far away from the recommended Luminance guidelines, and vice versa.

When the calculations are complete, you will be presented with statistics for the calculated metrics in the Statistics window. (Enable with the Statistics toggle button on the bottom toolbar.)