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The Reach of the Problem<\/p>\n
The researchers used DIALux and RELUX software applications \u2014 widely used in Europe \u2014 to model three types of luminaires and compare results against calibrated lab measurements. While the study focuses on these two platforms, the underlying issue lies in the structure of standard photometric file formats. That raises an open question: if AGi32 and Visual in North America also rely on IES file formats with similar geometric assumptions, could comparable simulation errors be present across all major platforms?<\/p>\n
The LEUKOS paper doesn\u2019t test those North American tools, but it does highlight fundamental limits in how traditional file formats represent spatially complex luminaires. As such, it\u2019s reasonable \u2014 though unconfirmed \u2014 to consider whether the challenge extends across the board until enhanced data formats are more broadly adopted.<\/p>\n
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A Closer Look at the Errors<\/p>\n
The research, led by Marek Mokran at Slovak University of Technology, tested three luminaire types against laboratory measurements. For compact fixtures, DIALux and RELUX delivered relatively accurate results \u2014 deviations stayed within 2\u20136%. But for luminaires with multiple spatially separated light sources, errors rose sharply. In one tested configuration, deviation exceeded 30% at a 1-meter offset \u2014 a scenario not uncommon in certain classroom or office settings. Even standard linear luminaires showed consistent 6% deviations at one-meter off-axis positions, which often correspond with task surfaces.<\/p>\n
To be clear: not all typical installations will suffer large errors. The most significant deviations appeared in near-field regions (within ~1 meter) and with specific luminaire geometries. At standard mounting heights around 2.5 meters \u2014 typical in offices \u2014 the study reports that deviations often fell to within 1\u20132% for linear fixtures. But the potential for larger errors remains, particularly when designers rely on simulations involving complex luminaires at close range.<\/p>\n
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Above: \u00a0Excerpt from “Simulation Inaccuracy in Lighting Design Caused by Geometric Assumptions in Luminaire Data”<\/p>\n
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The Format Problem Nobody Talks About<\/p>\n
The root cause isn\u2019t a software bug \u2014 it\u2019s a structural limitation of widely used photometric file formats. Both the IES (.ies) and Eulumdat (.ldt) formats were developed decades ago under assumptions suited to simpler lighting technology. These formats typically assume far-field conditions and are not designed to capture the spatial complexity of modern LED luminaires with non-continuous or modular emitting areas.<\/p>\n
As a result, real-world luminaires with non-emitting gaps or physically separated modules may be flattened into a single, smoothed abstraction. The software appears to treat these as uniform surfaces, producing renderings that look more seamless than the actual luminous environment. Researchers describe this as a kind of \u201cpseudo-near-field correction,\u201d though the study does not confirm the specific algorithms in use.<\/p>\n
At mounting heights of 2.5 meters or below \u2014 a common scenario \u2014 this simplification can break down, especially in luminaires with more spatially distributed emitters. Whether these approximations are built into the software intentionally or emerge from file limitations remains unclear.<\/p>\n
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What the Study Does (and Doesn\u2019t) Say<\/p>\n
The study avoids alarmism. It recommends that designers \u201cbe aware of possible inaccuracies in near field regions and reflect this in the design process.\u201d It does not suggest the entire industry is designing blindly or using tools that are universally unfit. Rather, it offers targeted evidence that in some design scenarios \u2014 particularly with non-uniform luminaires at short distances \u2014 simulation tools can deviate in meaningful ways from real-world results.<\/p>\n
It\u2019s worth asking: are current workflows accounting for this possibility? Or are designers assuming a level of fidelity that isn\u2019t always there? The study invites scrutiny, not panic.<\/p>\n
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Questions Around Liability and Simulation Integrity<\/p>\n
While the LEUKOS study doesn\u2019t weigh in on regulatory or legal implications, its findings raise questions. If lighting simulations lead to unexpected glare or non-uniformity, and those conditions compromise code compliance or visual comfort, where does responsibility lie? Could there be cases where narrowly passed simulations lead to real-world conditions that fall short of performance requirements?<\/p>\n
The study also mentions that luminaire definitions in data files can involve larger emitting surfaces than physically present \u2014 a practice that, if widespread, could affect UGR calculations. It stops short of suggesting intent or identifying specific manufacturers. Still, the potential for discrepancies between modeled and real-world glare may prompt designers to ask whether simulated UGR ratings can always be trusted at face value.<\/p>\n
What\u2019s missing, researchers note, is transparency. Many software platforms don\u2019t openly document how they handle spatial data distribution or near-field approximations. That opacity makes it hard for specifiers to assess which luminaires and which tools might be more susceptible to simulation mismatch.<\/p>\n
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Where the Industry Goes from Here<\/p>\n
Enhanced photometric data formats that incorporate near-field spatial measurements already exist \u2014 but they\u2019re not yet standard. Until that changes, designers face a decision: continue to rely on familiar workflows that may miss near-field inaccuracies, or build in validation steps to confirm that simulations match reality in critical applications.<\/p>\n
The authors of the LEUKOS study suggest a middle path: deliberate oversizing in simulation when near-field conditions apply, and empirical checks for projects where uniformity or glare control are especially sensitive.<\/p>\n
The study doesn\u2019t claim that the sky is falling. But it does shine a spotlight on a blind spot. Whether that becomes a call to action \u2014 or just another unsolved quirk of lighting design \u2014 remains to be seen.<\/p>\n","protected":false},"excerpt":{"rendered":"\u00a0December 3, 2025\u00a0 \u00a0 New research raises questions about photometric accuracy in industry-standard formats \u00a0 For more than…\n","protected":false},"author":2,"featured_media":328682,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[49],"tags":[199,79],"class_list":{"0":"post-328681","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-physics","8":"tag-physics","9":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/328681","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=328681"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/328681\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/328682"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=328681"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=328681"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=328681"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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