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GLDF over Photometry

Definition​

One convention in the GLDF is: which priority applies, if the same property is present in the photometry as well as in the GLDF:

Convention

If a property is present

  • in a linked photometry file
  • and in the GLDF itself

the following applies: GLDF overwrites photometry. This applies not only to properties with the same name, but to all semantically identical values.

This convention always prevails without having to be explicitly defined.

Examples​

Manufacturer Name​

Probably the most obvious use case that one might not even think of is the manufacturer's name. It occurs in both - photometry files like Eulumdat/IES and the GLDF - and is a mandatory field in these formats. What may seem obvious is a use case for this convention: The manufacturer name in the GLDF XML always applies. The manufacturer name in any photometry file is thus overwritten and has no meaning:

GLDF Container

CT & CRI​

Let's look at another example, in this case two photometric values: color temperature and the color rendering index. Lets assume that a referenced photometry file would have set these two properties as follows:

GLDF Container

(Image taken with DIAL LDT Editor, get it for free)

And the following GLDF XML:

<?xml version="1.0" encoding="UTF-8"?>
<Root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:noNamespaceSchemaLocation="https://gldf.io/xsd/gldf/1.0.0-rc.3/gldf.xsd">
    <Header>
        <!-- Skipped for clarity -->
    </Header>
    <GeneralDefinitions>
        <Files>
            <File id="photometryFile" contentType="ldc/eulumdat" 
                  type="localFileName">SomePhotometry.ldt</File>
        </Files>
        <Photometries>
            <Photometry id="photometry">
                <PhotometryFileReference fileId="photometryFile"/>
            </Photometry>
        </Photometries>
        <LightSources>
            <ChangeableLightSource id="lightSource">
                <Name>
                    <Locale language="en">E27 50W</Locale>
                </Name>
                <RatedInputPower>50</RatedInputPower>
                <ColorInformation>
                    <ColorRenderingIndex>90</ColorRenderingIndex>
                    <CorrelatedColorTemperature>4200</CorrelatedColorTemperature>
                </ColorInformation>
                <RatedLuminousFlux>200</RatedLuminousFlux>
            </ChangeableLightSource>
        </LightSources>
        <!-- Skipped for clarity -->
    </GeneralDefinitions>
    <ProductDefinitions>
        <!-- Skipped for clarity -->
    </ProductDefinitions>
</Root>

Based on the convention and the lines 24+25 in the GLDF above, the luminaire would be defined with:

  • ColorRenderingIndex ➝ 90
  • CorrelatedColorTemperature ➝ 4200

The values from the photometry file would be overwritten. On the opposite side, if lines 24+25 were not present in the GLDF XML, the values from the photometry would keep priority for this GLDF product:

  • ColorRenderingIndex ➝ 85
  • CorrelatedColorTemperature ➝ 4000