Vertical illuminance becomes critical when the visual task is no longer mainly the playing surface
ZC Lighting already has dedicated articles explaining horizontal versus vertical illuminance and broadcast Ev. This decision guide addresses a narrower question: when should vertical illuminance become a project gate that can change fixture selection, pole use, optics and acceptance?
The answer is task-based. When the project must reveal players, faces, balls or objects from defined viewing or camera directions, horizontal illuminance alone no longer describes the required visibility. The vertical reference planes and viewing directions must be included before design approval.
Use the minimum vertical-lighting model that matches the real task
Surface-led design
Routine recreational use with no defined camera or directional recognition requirement. Horizontal performance remains the primary design basis, subject to the governing sport standard.
General vertical visibility
Need to recognize people or aerial objects from common directions. Include representative vertical planes without building a full broadcast model.
Defined viewing direction
Streaming, video analysis, main-stand viewing or officiating creates a known directional requirement. Ev is calculated toward those specific viewpoints.
Multi-camera broadcast
Multiple camera axes, close-ups, slow motion and production standards make directional vertical illuminance, uniformity, flicker and color coordinated acceptance criteria.
Six situations that should move Ev earlier in the design process
Television or professional live production
Cameras expose players and objects, not only grass. Camera directions and image consistency must influence the optical strategy.
Fixed or PTZ cameras used as part of the venue product
Even below elite broadcast, poor vertical modeling can produce dark faces, flat images and exposure changes.
Coaching, officiating or tracking systems
Computer vision and analysis systems may depend on consistent object contrast from known camera positions.
Objects must remain visible above the horizontal field plane
Some sports require attention to ball visibility in flight. The solution must be sport- and standard-specific rather than simply adding uplight.
The venue has a dominant stand or official viewing axis
Directional vertical light may materially affect recognition and spectator experience from the main viewpoint.
Camera infrastructure is part of an approved upgrade plan
If camera locations are already planned, ignoring them during pole and optical design can create an avoidable future limitation.
“Vertical lux” is incomplete unless the plane and direction are defined
| Definition item | What must be stated | Why it matters |
|---|---|---|
| Reference height | The height or object plane at which Ev is evaluated | Different heights represent different visual tasks. |
| Direction | Camera axis, stand direction, four-direction grid or other defined orientation | Vertical illuminance changes with direction. |
| Calculation grid | Points, spacing and field area | Ensures design and commissioning assess the same geometry. |
| Uniformity measure | The required directional uniformity definition | Average Ev alone can hide dark player positions. |
| Operating scene | Which fixtures and output levels are active | Training and broadcast scenes may have different Ev performance. |
| Camera / viewer list | Which viewpoints are acceptance-critical | Prevents unnecessary optimization for irrelevant directions. |
Improving Ev can change more than the photometric report
What good Ev planning can improve
- Player and object recognition from required viewpoints
- Camera exposure consistency
- Modeling of faces and uniforms
- Visibility of vertical advertising and objects
- Future camera readiness when geometry is preserved
What must be controlled
- Higher-angle intensity and glare
- Spill and off-site visibility
- Additional cross-lighting and fixture count
- Power and structural capacity
- Potential conflicts between camera directions
That is why Ev should become a design input before fixtures are frozen. Trying to “add vertical lux” after the horizontal design is complete can force more aggressive aiming or extra sources that harm glare and spill control.
Decide Ev requirements in five steps
Key takeaways
2. Do not specify “vertical lux” without a height, direction and grid.
3. Use only the vertical-lighting complexity required by the real task.
4. Adding Ev can affect glare, spill, fixture count and pole capacity, so define it before equipment is frozen.
5. Broadcast projects require coordinated camera, flicker, color and uniformity requirements—not Ev in isolation.
Frequently asked questions
Does every sports field need vertical illuminance criteria?
No. The applicable sport standard and project use determine whether explicit Ev criteria are needed. Routine recreational projects may be primarily surface-led, while camera or directional-recognition tasks make Ev more important.
Is vertical illuminance only for television broadcast?
No. Streaming cameras, video analysis, officiating, dominant spectator viewpoints and some object-recognition tasks can also justify directional vertical-lighting checks.
Can average horizontal lux be high while vertical visibility is poor?
Yes. A bright playing surface does not guarantee that people and objects are well lit from a camera or viewer direction.
How many vertical directions should be calculated?
Only as many as the governing standard, tender and actual viewing/camera tasks require. Unnecessary directions add complexity without necessarily improving the project.
Can Ev be improved after installation by tilting fixtures more?
Sometimes output can be redistributed, but aggressive late-stage aiming can increase glare and spill or reduce horizontal performance. The safer approach is to design vertical requirements from the start.
Should Ev be measured during commissioning?
If Ev is an acceptance criterion, the measurement method, grid, height, direction and operating scene should be agreed before handover so the field test matches the design basis.
Sources and professional guidance
- SLL LG4 Sports Lighting (2023).
- UEFA Stadium Lighting Guide 2023.
- ANSI/IES RP-6-24: Recommended Practice—Lighting Sports and Recreational Areas.
The decision frameworks in this article are practical ZC Lighting editorial tools. Always verify the latest project-specific tender, governing-body, local-code and authority requirements.