\section{Introduction}
On-Set Virtual Production (OSVP) is combining a tracked camera with a real-time rendered frustum, to achieve shorter production time through LED-panels compared to green-screen techniques. While correct lighting of the virtual set is a mixture of multi-primary diffuse or spot lighting fixtures on the actors and set, the LED-panels itself are used for the inner-frustum background seen by the camera, as well as indirect lighting from the outer-frustum content. This dual use of LED-walls brings new challenges in predictable and colour correct results. The standard format for predicting luminance over angles are mostly used in architectural or stage lighting simulation describes luminance and does not include colour over angle.

\section{Related Works}
Colour-Over-Angle Investigations \cite{ng_investigation_2025} are approaching 


Predict Light 
Lighting on filmsets 
Colour Correction Approaches


As shown by \cite{legendre_practical_2016} a mixture of LED-walls with tristimulus RGB gamuts can be matched to RGB+ light settings. \cite{yu_real-time_2025}
For light fixtures the global device type format (GDTF) provides photometric data through luminous intensity distribution curve (LIDC) in EULMDAT (.ldt) or IES format containing only luminous data. \cite{iesna_lm63_02}. Opsira Rayfile\cite{jacobs_rayfiles_2015}

OpenVPcal is approaching correction through a 1D-LUT applied to the camera, based on calibration patterns shown on the LED wall, aiming for less metameric mismatch and EOTF to OETF calibration. \cite{payne_openvpcal_2022}

Regarding colour stability the IDMS provided by the ICDM focus on 9.5/9.6 delta UV. \cite{international_committee_for_display_metrology_information_2025}

SMPTE states... \cite{long_color_nodate}

%ISO 12646 (Graphic technology – Displays for colour proofing) is calculating the $delta Gamma$ based on neutral gray, but is not offering information how the colour changes over angles for a display. \cite{noauthor_iso_nodate} \textit{could be removed}

It exists one comparable thesis on Investigation of Color-Over-Angle in Multi-Chip Array LEDs dissertation (2025) spervermerk bis 2028 \cite{ng_investigation_2025}

% Strahlendaten von LED-tiles enthalten prinzipiell die relevanten Daten, da durch 
One could assume that the LED beam data for optic simulation for the individual LED in the panel could be used to model the lambertschen illumination profile as a sum of them. As to this moment there are multiple factors influencing LED panels like receiver card and processing, scan-mux ratio, pixel pitch and coating or shader design, we expect different results for similar LED panels. Additionally LED panel manufacturers not always mention the batch/binning data or information about the individual LED characterstics.


%https://www.researchgate.net/publication/279251758_LED_champing_statistically_blessed -> shows CoA for fixed color temperature.

\section{Methodology}
In order to predict colour mismatch based on the observing position of the camera, the standard procedure for generating LIDC was extended by a colorimetric measurement of an LED-tile under ICDM measurement conditions. In addition to the colorimeter a film-camera was positioned in 8m distance to the robo-gonimeter filming the rotation of the LED-tile in steps. 
By extracting an .ies profile containing als the CCT over angle, the luminous intensity distribution curve can be used inside the game-engine (unreal engine 5.5 in this case).
By adopting the rayfile measurement process mentioned before, one can expect better understanding of the influence of the individual panel in the signal processing chain from opto-opto-transfer-function on a filmset.

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The measured CoA data represented in figure \ref{fig:ex1} is then baked into a Polar-Lookup-Table (LUT) containing azimut angle and 

\section{Conclusion}
%Wann sind farbdrifts akzetabeL?
The presented approach enables filmmakers to predict the influence of colour drift induced by the LED-panel into OSVP filmsets prior recording. 

As our panel was only measured with a $D_{65}$ White Test Pattern by the Brompton S8 LED processor, it is likely that colour drifts appear to be related to the brightness of the LED panel.



\section{Outlook}
Might be interesting to compare different manufacturing methods in LED-panels like COB, SMD, pixel pitches.
Measuring and predicting reflective behaviour of LED-tiles and contrast as BRDF is interesting, tends to happen more often that lights shines on the LED wall.

% das eigentlich neue könnte sein, dass man aufgrund des bekannten (gemessenen verhaltens) der farbdrift nun als raytracing simuliert werden könnte

As shown in figure \ref{fig:polarCoA}. the color drift can be visualized by changing correlated color temperature CCT over angles.

\section{Background}

The presented poster is part of a research project aiming for production support systems in the context of virtual production. Based on interviews with filmschools and professional DOPs or VFX supervisors a connected control between multiprimary lighting fixtures (typically controlled via ArtNet, DMX) and light emitted by or reflected at the LED wall are an ongoing challenge in OSVP environments. The poster is contributing to the aspects of a digtial representation or digital twin supporting standard for LED-tiles, to reduce friction between existing standards like GDTF, manufacturers data sheets.

Mentioned in Virtual Production Handbook \cite{noauthor_ves_2023} correct colour pipelines are cruical in cinematography for intended storytelling and the virtual staging of a virtually recreated film set that is not breaking the illusion to the observers.



Further as lighting and video are sharing the CIE 1931 chromacity diagram and evolved metrics based on the CIE, ANSI, IES or SMPTE, Academy
is important, SMPTE Summit OETF --> EOTF pipeline needs formalisation for OSVP. \cite{swords_emergence_2024}

of LED-panels compared to green-screen techniques. While 