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Light Sources

LightSource Description​

LightSources is the fifth child-element of GeneralDefinitions - the part in the XML where global and reusable elements are defined (imagine them as the building blocks of each luminaire). The definition of LightSources is optional.

Location in XSD​

LightSource location in XSD

LightSource types​

There are three fundamentally different types that can be distinguished, how a LightSource can be defined:

Optional light source types
  1. ChangeableLightSource
    Represents a classic user-replaceable light source with a socket. Typically, such a lamp determines the light color, luminous flux and the nominal power.
  2. FixedLightSource
    This light source is permanently installed, and the end user no longer has any influence on light color, luminous flux and rated power. This is almost always true for LEDs.
  3. MultiChannelLightSource
    As the name already suggests and in contrast to the first two, the MultiChannelLightSource supports multiple light channels. Supporting applications like DIALux allows to control each channel seperatly and adjust the lumanire to the current requirements of a lighting scene.

XSD of ChangeableLightSource​

Changeable light source

XSD of FixedLightSource​

Fixed light source

XSD of MultiChannelLightSource​

Multichannel light source

XML example​

Below is a longer example where all three types are defined with minimal data. In real product data, if possible, many more properties should be defined to better describe the product.

<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. See "Header" documentation -->
  </Header>
  <GeneralDefinitions>
    <Files>
      <File id="phptometryFile" contentType="ldc/eulumdat" 
            type="url">https://example.org/eulumdat.ldt</File>
      <File id="spectrumRedFile" contentType="spectrum/text" 
            type="url">https://example.org/spectrumRed.txt</File>
      <File id="spectrumGreenFile" contentType="spectrum/text" 
            type="url">https://example.org/spectrumGreen.txt</File>
      <File id="spectrumBlueFile" contentType="spectrum/text" 
            type="url">https://example.org/spectrumBlue.txt</File>
    </Files>
    <Photometries>
      <Photometry id="photometry">
        <PhotometryFileReference fileId="phptometryFile" />
      </Photometry>
    </Photometries>
    <Spectrums>
      <Spectrum id="spectrumRed">
        <SpectrumFileReference fileId="spectrumRedFile" />
      </Spectrum>
      <Spectrum id="spectrumGreen">
        <SpectrumFileReference fileId="spectrumGreenFile" />
      </Spectrum>
      <Spectrum id="spectrumBlue">
        <SpectrumFileReference fileId="spectrumBlueFile" />
      </Spectrum>
    </Spectrums>
    <LightSources>
      <!-- Create a changeable light source with E27 socket -->
      <ChangeableLightSource id="lightSource-changeable">
        <Name>
          <Locale language="en">Incandescent lamp</Locale>
        </Name>
        <RatedInputPower>40</RatedInputPower>
        <ColorInformation>
          <ColorRenderingIndex>95</ColorRenderingIndex>
          <CorrelatedColorTemperature>2700</CorrelatedColorTemperature>
        </ColorInformation>
        <Socket>E27</Socket>
        <RatedLuminousFlux>500</RatedLuminousFlux>
      </ChangeableLightSource>
      <!-- Create a fixed LED light source -->
      <FixedLightSource id="lightSource-fixed">
        <Name>
          <Locale language="de">LED</Locale>
        </Name>
        <RatedInputPower>40</RatedInputPower>
      </FixedLightSource>
      <!-- Create RGB multi channel light source -->
      <MultiChannelLightSource id="lightSource-multiChannel">
        <Name>
          <Locale language="en">RGB light source</Locale>
        </Name>
        <RatedInputPower>40</RatedInputPower>
        <Channels>
          <Channel type="Red">
            <DisplayName>
              <Locale language="en">Red channel</Locale>
            </DisplayName>
            <SpectrumReference spectrumId="spectrumRed" />
            <PhotometryReference photometryId="photometry" />
            <RatedLuminousFlux>200</RatedLuminousFlux>
          </Channel>
          <Channel type="Green">
            <DisplayName>
              <Locale language="en">Green channel</Locale>
            </DisplayName>
            <SpectrumReference spectrumId="spectrumGreen" />
            <PhotometryReference photometryId="photometry" />
            <RatedLuminousFlux>200</RatedLuminousFlux>
          </Channel>
          <Channel type="Blue">
            <DisplayName>
              <Locale language="en">Blue channel</Locale>
            </DisplayName>
            <SpectrumReference spectrumId="spectrumBlue" />
            <PhotometryReference photometryId="photometry" />
            <RatedLuminousFlux>200</RatedLuminousFlux>
          </Channel>
        </Channels>
      </MultiChannelLightSource>
    </LightSources>
    <Equipments>
      <!-- Reference the changeable light source in an equipment first -->
      <Equipment id="equipment">
        <LightSourceReference changeableLightSourceId="lightSource-changeable" />
        <RatedInputPower>40</RatedInputPower>
      </Equipment>
    </Equipments>
    <Emitters>
      <!-- Reference the equipment to finally use the defined changeable light source -->
      <Emitter id="changeableLight-emitter">
        <ChangeableLightEmitter>
          <PhotometryReference photometryId="photometry" />
          <EquipmentReference equipmentId="equipment" />
        </ChangeableLightEmitter>
      </Emitter>
      <!-- Reference the fixed light source directly and add a photometry here -->
      <Emitter id="fixedLight-emitter">
        <FixedLightEmitter>
          <PhotometryReference photometryId="photometry" />
          <LightSourceReference fixedLightSourceId="lightSource-fixed" />
          <RatedLuminousFlux>6600</RatedLuminousFlux>
        </FixedLightEmitter>
      </Emitter>
      <!-- Reference the multi channel light source -->
      <Emitter id="multiChannel-emitter">
        <MultiChannelLightEmitter>
          <LightSourceReference multiChannelLightSourceId="lightSource-multiChannel" />
        </MultiChannelLightEmitter>
      </Emitter>
    </Emitters>
  </GeneralDefinitions>
  <ProductDefinitions>
    <!-- Finally, use the Emitter to define the product here -->
    <!-- (Skipped for clarity. See "Global Product Data" documentation) -->
  </ProductDefinitions>
</Root>

Referencing a light source​

Once declared, all light sources can be referenced in subsequent XML elements via their id attribute one or several times.

Important

What is particularly remarkable about the XML example above is how differently ChangeableLightSource and FixedLightSource are referenced. While at first glance this adds complexity, it better represents the reality:

For the usage of a ChangeableLightSource an element of the type Equipment must be defined first. Which combines a ChangeableLightSource with an optional ControlGear. Subsequently, this Equipment is finally referenced in the Emitter. The FixedLightSource however, is referenced directly in the Emitter itself. This also applies to the luminous flux, which is defined directly in the Emitter, and not the light source, as well.

This occurs because a fixed light source like LED is an integral part of the entire luminaire. They are not interchangeable at all, and therefore can only be measured as a whole. Whereas a ChangeableLightSource - like classic bulbs with a socket - can also be photometrically measured on their own. And are therefore defined separately in a likewise exchangeable Equipment element.

Optional metadata​

It is possible to optionally specify various metadata inside a light source to complement its description with further details:

  • Name
    Translatable name of the light source
  • Description
    Translatable description of the light source
  • Manufacturer
    Manufacturer name of the light source
  • GTIN
    Global Trade Item Number (GTIN) of the light source
  • RatedInputPower
    Input power consumed by the light source, when the luminaire is turned on
  • RatedInputVoltage
    Voltage at which the light source operates normally
  • PowerRange
    Minimal, maximal and recommended light source power
  • LightSourcePositionOfUsage
    Light source usage position (Horizontal/Vertical), possibly with range of angle
  • EnergyLabels
    European Union energy label, accoring to the energy consumption labelling scheme
  • SpectrumReference
    Spectrum of radiation. See Spectrum
  • ActivePowerTable
    Consumption of the power corresponding to the dim level of the light source. It is described as a table of power factor between 0-1 in relation to the luminous flux factor between 0-1
  • ColorInformation
    Light source color appearance
  • LightSourceImages
    List of images depicting the light source