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Signage Photometric Plan: Sign Lighting, Spill Light & Permit Review Illuminated signs are often treated as a small part of an exterior lighting package, but they can create very concentrated light close to roads, sidewalks, neighboring properties, and building façades. A signage photometric plan helps show how that light is distributed before the sign is installed and gives reviewers a clear technical drawing to evaluate during permit review. At Stetra Lighting, we use photometric modeling for illuminated monument signs, pylon signs, internally illuminated signs, LED displays, and signage that is coordinated with a larger site-lighting design. The goal is not simply to make the sign bright. The goal is to understand where the light goes, how quickly it falls off, and whether the proposed installation creates unwanted spill around the site. Order a Photometric Plan Illuminated Valero pylon sign modeled in a nighttime photometric study What Is a Signage Photometric Plan? A signage photometric plan is a calculated lighting study focused on an illuminated sign and the areas affected by it. Depending on the project and local review requirements, the study can show: Point-by-point foot-candle values around the sign Light distribution across nearby pavement, sidewalks, or property False-color illumination maps Light spill beyond the immediate sign area Fixture locations, mounting positions, and aiming The relationship between the sign and nearby site lighting Calculated values at specific review points or boundaries The exact requirements vary by municipality and by sign type. Some reviewers are mainly concerned with spill light, while others may ask for a more detailed photometric or brightness study for an illuminated or electronic display. For a broader explanation of the process, see our guide to photometric plans. Real Project Example: Illuminated Pylon Sign One of the projects shown here involved an illuminated Valero pylon sign placed within an active commercial site. Modeling the sign in 3D helps us evaluate the sign as part of the actual site rather than as an isolated object. Valero pylon sign shown on the site plan during photometric modeling The model shows the sign location, surrounding pavement, site geometry, and nearby features. This is useful because an illuminated sign can affect more than the sign face itself. Downlighting, integrated accent lighting, price displays, and nearby site fixtures can all contribute to the calculated light levels. For gas stations and fuel sites, signage is often only one component of the exterior lighting package. See our gas station photometric plan example for the broader site-lighting approach. LED Sign Photometric Study and Spill Light Electronic and LED signs can require a different kind of review because the sign face itself can be a significant light source. A useful LED sign photometric study should therefore look beyond a visual render and quantify how much illuminance reaches the surrounding area. LED monument sign modeled at night for a signage photometric study The image above shows a digital monument sign modeled at night. In this type of analysis, the sign is placed into the actual site context so the light can be evaluated relative to roads, sidewalks, buildings, and surrounding property. A false-color view makes the falloff much easier to understand: False-color photometric analysis showing light spill around an LED sign Warmer colors show the areas receiving higher calculated illuminance, while cooler colors show the light decreasing away from the sign. This makes it easy to identify the strongest zones and see whether light is extending farther than expected. Why Point-by-Point Foot-Candle Values Matter A photometric render is useful for understanding appearance, but permit review usually needs measurable information. A point-by-point grid provides that technical layer. Point-by-point foot-candle grid for an illuminated sign photometric plan In this project example, the modeled calculation area shows an average of 0.18 foot-candles and a maximum of 13.2 foot-candles. These are project-specific results, not universal sign-lighting targets. The important point is that the study documents exactly where the higher values occur and how quickly they decrease away from the sign. That distinction matters because a single maximum value does not describe the entire site. Reviewers may need to understand the light at a road edge, property line, neighboring parcel, sidewalk, or another defined location. False-Color Analysis for Sign Lighting False-color analysis is particularly helpful for signage because the light source can be concentrated in a small area. False-color site analysis showing illumination distribution around a monument sign Instead of reading dozens of individual values, the reviewer can immediately see the pattern of illumination. The point-by-point calculation grid can then be used to verify exact values at the locations that matter. For exterior commercial projects, we often use both methods together: 1. 3D view — confirms fixture/sign placement and overall context. 2. False-color view — shows the shape and falloff of the illumination. 3. Calculation grid — provides exact foot-candle or lux values. 4. Summary data — documents average, minimum, maximum, or other requested criteria. Signage as Part of a Complete Exterior Lighting Design Sign lighting does not always need to be analyzed separately from the building and parking areas. On many projects, the better approach is to model everything together. The restaurant example below includes façade lighting, site poles, architectural accent lighting, and illuminated building signs. Nighttime 3D render of restaurant signage coordinated with exterior lighting This type of coordinated model helps prevent a common problem: designing the sign, building, and parking lot as separate systems without understanding their combined effect. False-color exterior lighting analysis for a restaurant with illuminated signage The false-color view shows how the individual lighting components overlap across the property. This is especially useful near entrances, drive aisles, pedestrian areas, and property edges. For parking-focused sites, see our parking lot photometric plan project example. What We Need to Prepare a Sign Photometric Plan A typical signage study starts with the information already available for the permit package: Site plan, survey, PDF, or DWG Sign location and dimensions Sign elevation or manufacturer drawing LED/display/fixture photometric information when available Mounting height and orientation Local review comments or ordinance criteria Nearby