The challenge
A cockpit display and its backlit gauges must meet two conflicting requirements at once: stay readable in full sunlight while not blinding the driver after dark or producing distracting reflections in the windshield. The OEM also specifies exact luminance values (in cd/m²) and a minimum brightness uniformity across the whole surface. The classic route — a series of physical backlight-module prototypes and luminance measurements — is costly and slow: every tweak to the diffuser, lens, or LED layout means another unit and another measurement session.
The solution
The full optical path was modeled in TracePro: the backlight LED array, diffuser, optical layers, cover glass, and cockpit housing geometry, with real surface properties (transmission, scattering, reflections). After ray tracing, TracePro generates a luminance map directly in cd/m² (nits) — the same unit used in OEM requirements. The True Color view shows what the glow actually looks like, while False Color instantly flags overexposed and underexposed zones as well as glare and reflection sources in the glass.
For a trustworthy result, the automatic importance sampling option is key: it directs rays toward where the most significant light lands, so the luminance map converges to a smooth, low-noise image for the same ray budget. TracePro's documentation shows this on a reference test — for the same scene, the average luminance stays practically unchanged (around 1666 vs. around 1660 cd/m²), but the map with importance sampling enabled is noticeably less grainy. Design decisions are made on a clean image, not on noise.
Without importance sampling — the luminance map is clearly grainy (avg. approx. 1666 cd/m²).
With importance sampling — the same scene, the map is noticeably smoother (avg. approx. 1660 cd/m²).
Results
- Compliance assessment in OEM units — luminance and its uniformity read directly from the model in cd/m², with no physical-sample measurement.
- Early detection of glare and reflections — the False Color map shows hot zones and reflections in the glass right at the geometry stage, when a change is cheap.
- Fewer hardware iterations — refining the diffuser and LED layout in the model reduces the number of "try it and see" prototypes.
- A trustworthy result — importance sampling produces a smooth luminance map, so variants are compared on data, not sampling artifacts.
Why TracePro
Dlaczego to narzędzie. Luminance and radiance mapping is a native TracePro function for assessing illumination and optical efficiency. The tool calculates exactly the photometric quantities (cd/m²) used to measure readability and visual comfort — without needing diffraction or aberration analysis, which are the domain of other tools.
Want to check the readability and glare of your display or backlight before a prototype exists? Request a TracePro trial or get in touch with us — we'll show you how to build this kind of analysis for your system.
Uwaga. An illustrative example, based on the luminance/radiance map functionality in TracePro (TracePro 2026 documentation, "Example Using Luminance/Radiance Maps"). The values given are for illustration only.