Design the beam. Check it against R149.
Cutline traces light through an LED projector or a reflector, ray by ray. It aims the beam the way an approval laboratory does and measures every point, line and zone of UN Regulation No. 149. It also checks any lamp's light distribution against every market, and where lamps sit on the vehicle. It runs in your browser, and your files stay on your computer.
The default projector's beam, traced with 20 million rays and aimed by its cut-off: 26 of 26 requirements met.Intended cut-offPassNearFail
Every requirement, with its paragraph
For the beam class you choose, Cutline lists every limit in the 01 series of R149 and measures it through a receiver the size the regulation sets. It gives the margin and the statistical error of each value, and cites the table or paragraph it comes from. This is the default projector's sheet, computed when this page was built.
UN R149, 01 series: Class C passing beam
Default LED projector, right-hand traffic, aimed by three lines
Meets the regulation: 26 of 26| Requirement | Measured | Limit | Margin | Result |
|---|---|---|---|---|
| Cut-off | ||||
| Cut-off sharpness at 2.5°LAnnex 6 §2.2.2 (p. 75) | 0.31 | G from 0.13 to 0.4 | +22% | Pass |
| Cut-off linearity, 1.5° to 3.5°Annex 6 §2.2.3.1 (p. 75) | 0.04° | inflections within 0.2° | +82% | Pass |
| Glare | ||||
| Zone IIITable 6 Parts A and C (pp. 23–24) | 434 cd ±5% | nowhere above 625 cd | +31% | Pass |
| BRTable 6 Part A (p. 23) | 288 cd ±9% | at most 1,750 cd | +84% | Pass |
| Segment BLLTable 6 Part A (p. 23) | 36.3 cd ±6% | nowhere above 625 cd | +94% | Pass |
| B50LTable 6 Part A (p. 23) | 46.2 cd ±8% | at most 350 cd | +87% | Pass |
| Overhead signs | ||||
| S50 + S50LL + S50RRTable 6 Parts A and B (pp. 23–24) | 317 cd ±6% | at least 190 cd | +67% | Pass |
| S100 + S100LL + S100RRTable 6 Parts A and B (pp. 23–24) | 494 cd ±5% | at least 375 cd | +32% | Pass |
| Road ahead | ||||
| PTable 6 Part A (p. 23) | 109 cd ±10% | at least 63 cd | +73% | Pass |
| 75RTable 6 Part A (p. 23) | 13,987 cd | at least 12,100 cd | +16% | Pass |
| 50LTable 6 Part A (p. 23) | 8,519 cd | 5,000 cd to 37,000 cd | +70% | Pass |
| 50VTable 6 Part A (p. 23) | 8,644 cd | at least 5,100 cd | +69% | Pass |
| 50RTable 6 Part A (p. 23) | 16,134 cd | at least 10,100 cd | +60% | Pass |
| Segment 50Table 6 Part A (p. 23) | 6,759 cd ±3% | everywhere at least 2,540 cd | +166% | Pass |
| Segment 40LLTable 6 Part A (p. 23) | 3,351 cd ±5% | everywhere at least 850 cd | +294% | Pass |
| 40LTable 6 Part A (p. 23) | 7,499 cd ±3% | at least 2,800 cd | +168% | Pass |
| 40RTable 6 Part A (p. 23) | 7,783 cd ±3% | at least 2,800 cd | +178% | Pass |
| Segment 40RRTable 6 Part A (p. 23) | 3,365 cd ±5% | everywhere at least 850 cd | +296% | Pass |
| 25VTable 6 Part A (p. 23) | 14,877 cd | at least 2,500 cd | +495% | Pass |
| Segment 25LTable 6 Part A (p. 23) | 2,156 cd ±4% | everywhere at least 1,180 cd | +83% | Pass |
| Segment 25Table 6 Part A (p. 23) | 6,307 cd ±3% | everywhere at least 1,700 cd | +271% | Pass |
| Segment 25RTable 6 Part A (p. 23) | 2,013 cd ±4% | everywhere at least 1,180 cd | +71% | Pass |
| Segment 15Table 6 Part A (p. 23) | 741 cd ±4% | everywhere at least 425 cd | +74% | Pass |
| Segment 10Table 6 Part A (p. 23) | 6,834 cd ±3% | everywhere at least 500 cd | +1267% | Pass |
| Foreground | ||||
| Segment 10 and belowTable 6 Part A (p. 24) | 9,030 cd | at most 0.8 × 50R | +30% | Pass |
| Flux | ||||
| Minimum flux§4.5.3.2 and Tables 3a/3b (pp. 16–17) | 1,230 lm | source ≥ 1000 lm, or Zone I ≥ 400 lm and Zone II ≥ 200 lm | +23% | Pass |
Aimed 0.01° down and 0.08° left. Traced with 20 million rays; a passing value within 10% of its limit, or within twice its statistical error, is marked near.
Aimed the way the laboratory aims it
R149 measures a lamp after it has been aimed by its own cut-off. Cutline follows the instrumental method of Annex 6, so a beam that looks right on screen also has to sit right after aiming.
Find the cut-off
A scan rises through the beam at 2.5° on the driver's side, in steps of 0.05°. The steepest fall of log intensity marks the cut-off, and it goes onto line B, 0.57° below the horizon.
Aim it sideways
By the method the applicant chooses: three vertical scans across the rising edge, or one scan along the line 0.2° down. Either way, the elbow lands where the regulation puts it.
Measure through the receiver
Every value is the average over a 65 mm receiver at 25 m. Where too few rays arrive, the receiver widens and the value carries its error, so noise is never mistaken for a pass.
The scan at 2.5°L through the default projector's beam. Its steepest fall is G = 0.31 over 0.1°, inside the 0.13 to 0.40 that R149 allows, and after aiming it sits on line B.
Two kinds of lamp, traced in section
Every value can be changed. Colour dispersion in the lens, surface texture, haze and the energy lost at each surface are all part of the trace. The projector's starting design meets Class C; the reflector's is a starting point that does not yet.
LED projector
An ellipsoidal reflector focuses the LED onto a shield, and an aspheric lens projects the shield's edge as the cut-off.
- Requirements met
- 26of 26
- Optical efficiency
- 37%
- Peak intensity
- 16.6kcd
Multi-facet reflector
A faceted paraboloid places one image of the LED per facet under the cut-off; no lens, no shield.
- Requirements met
- 20of 26
- Optical efficiency
- 55%
- Peak intensity
- 64.4kcd
Any lamp, every market
Open an IES or EULUMDAT file of a headlamp or a signal lamp, or send the beam you traced. Cutline checks it against each market by that market's own laboratory method, and against your own targets.
See it as an engineer does
Isolux at 25 m or intensity, on the road surface or a target, in false colour or heat, on a scale you set. A uniformity map shows each direction against its surroundings, so dark patches and stripes stand out and the cut-off does not.
Check every market
UN R149 for right- and left-hand traffic, UN R123, UN R148 for signal lamps, FMVSS 108, CMVSS 108, Taiwan's VSTD and India's AIS drafts. Each value cites its source; national rules show which UN series they stand on.
Share the report
One HTML file with the summary, the pictures, every requirement and your targets, ready to print to PDF. Markets Cutline cannot check from an official source are listed with the reason, never guessed.
Where the lamps sit on the vehicle
Open an STL, OBJ or glTF model of the vehicle and click where each lamp goes. Cutline checks UN R48 and FMVSS 108: presence and number for the vehicle's category, heights to the apparent surface, distance from the outer edge, the separation of each pair, and the angles of geometric visibility, casting rays to find any bodywork that hides a lamp.
What it does not do
Cutline is for concept design. A passing result means the simulated design meets the limits, not that a lamp would pass at a technical service.
- Type-approval photometry only. No colour, run-up time, conformity-of-production allowances, bend lighting or adaptive driving beams.
- One optical unit, one LED. A production headlamp often combines several modules. The reflector's starting design still fails a few Class C requirements.
- Simple scattering. Lens texture and outer-lens haze are modelled; dust, ageing and heat are not.
- One distribution at a time. Rules comparing two states of a lamp, such as stop to tail ratios, are listed for you to check.
- Meshes, not STEP. Export the vehicle from CAD as STL, OBJ or glTF. Rules relative to the rear window or other lamps are listed to check by hand.
- Sources you can check. Every limit cites the official text, and the documentation lists the choices each regulation leaves open.