Cylindrical / Semi-cylindrical Illuminance Technical Hub

Semi-cylindrical illuminance (Esc) averages on an oriented vertical semi-cylinder—better than horizontal lux alone for recognizing oncoming pedestrians. CJJ 45, JGJ/T 163 and GB/T 50034—2024 list Esc separately. Field points are often at ~1.5 m with defined orientation; calibrate with Esc=(2/π)·I/l² on an optical bench. HZYMTECH LUX-100D-C (semi) / LUX-100D-F (full) with LuxPartner (Android / Windows / Linux) cover grids, logging and PDF reports.

Esc supports facial recognition and pedestrian security; full cylindrical illuminance evaluates spatial modeling. Sidewalk/plaza acceptance needs Esc—horizontal lux alone is not enough.

What is Esc, and how does it differ from cylindrical and horizontal illuminance?

Semi-cylindrical illuminance (Esc) is the average illuminance on an imaginary vertical semi-cylinder surface, oriented by the inward normal of its flat rear face—more relevant than horizontal illuminance alone for recognizing oncoming pedestrians. Full cylindrical illuminance averages over a full vertical cylinder for surround lighting and spatial modeling. Chinese road/nightscape standards (CJJ 45, JGJ/T 163) and GB/T 50034—2024 include Esc in design and acceptance. Field work uses semi-/full-cylindrical receptors at about 1.5 m with defined orientation; meter performance follows GB/T 39388 / CIE S 023; calibration commonly uses an optical bench with Esc≈(2/π)·I/l², reference plane ≈0.067×d, and stray-light control. HZYMTECH LUX-100D-C / LUX-100D-F provide portable Esc and cylindrical measurement; LuxPartner (Android app, Windows / Linux desktop) adds live reading, uniformity/integral/logging and report export across the standards–field–traceability chain.

Horizontal vs Esc vs full cylindrical—which to use?

Table: horizontal vs Esc vs full cylindrical illuminance
Metric	Geometry	Typical use
Horizontal Eh	Horizontal plane	Road/task brightness; carriageways and general tasks
Semi-cylindrical Esc	Vertical semi-cylinder (oriented)	Facial recognition, pedestrian security; sidewalk/plaza/outdoor acceptance
Full cylindrical illuminance	Full vertical cylinder average	Spatial modeling / surround; architecture, museums

How to measure Esc on site (steps)

Confirm cited standards (CJJ 45 / JGJ/T 163 / GB/T 50034, etc.), Esc limits and viewing direction.
Use a semi-cylindrical receptor (e.g. LUX-100D-C); choose LUX-100D-F for full cylindrical surround.
Level the tripod; height is often 1.5 m on the road centre line (follow the standard).
Aim the semi-cylinder per the required orientation; keep operators out of the optical path.
Log stable readings; report coordinates, height, orientation, meter model and calibration status.
Optionally use LuxPartner (Android / Windows / Linux) for uniformity grids, integral/timed logging and PDF export.

FAQ

How does Esc differ from horizontal illuminance?

Horizontal illuminance checks whether the ground/task surface is bright enough; Esc averages on a vertical semi-cylinder and better reflects facial recognition and pedestrian security. Sidewalk standards often require both—neither replaces the other.

Is horizontal illuminance alone enough for acceptance?

No—where Esc is a listed evaluation metric (sidewalks, nightscape walkways/plazas), acceptance must include Esc.

What sidewalk Esc height and CJJ 45 limits apply?

CJJ 45 often uses 1.5 m on the centre line. Example Esc,min: Level 1 ≈3 lx, 2 ≈2 lx, 3 ≈1.5 lx, 4 ≈1 lx—verify against the official text.

How are Esc meters calibrated, and what is the formula?

Optical-bench method: with the probe axis perpendicular to the ray, Esc=(2/π)·I/l²; measure to the internal reference plane (~0.067×diameter) and baffle stray light. Expanded uncertainty is often about 1–1.3% (k=2).

LUX-100D-C vs LUX-100D-F—which to choose?

Choose LUX-100D-C (semi-cylindrical) for sidewalk/plaza/security Esc acceptance; LUX-100D-F (full cylindrical) for architectural surround and museums. Use a PPFD probe for plant photosynthesis.

Which platforms does LuxPartner support, and what can it do?

LuxPartner offers an Android app plus Windows and Linux desktops. Connect via Bluetooth on phone, or USB serial / Bluetooth on PC; live readings, uniformity grids, integral and timed logging, PDF/text export, with session files shared across devices.

Is a large Esc change after 180° rotation normal?

Yes—the semi-cylinder is oriented; front vs back can differ greatly. Record the standard viewing direction in the report.

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