First decide what the image is claiming.
“Make the courtyard sunny” and “show sunlight at a stated time” are different briefs. A marketing image may use a plausible, attractive lighting condition to communicate atmosphere. A date-specific image implies a verifiable sun direction. A formal shadow or daylight assessment asks an additional, more demanding question about a measurable impact. Do not quietly substitute one for another.
Write the intended use on the image brief: concept presentation, sales illustration, time-specific comparison, or formal assessment input. That decision governs how precisely you must record location, orientation, surrounding geometry and time. A polished rendering cannot recover missing evidence after the fact.
If a client might reasonably interpret the image as evidence of direct sunlight at a particular hour, either support that interpretation with documented inputs or label the scene as illustrative. The disclaimer should sit with the image, not in an unrelated contract appendix.
This guide addresses visualisation production and review. It is not a method for demonstrating compliance with local daylight, overshadowing, solar-access or planning requirements. Those assessments need the applicable specialist methodology and independently reviewed inputs.
Lock true north, site position and model orientation before touching the sun.
Sun direction is a spatial relationship, not a colour preset. Start with the site latitude and longitude, the issued survey or site plan, and the model's north convention. A model can be perfectly aligned on screen and still have its project north rotated relative to true north. Record which north each file uses and the transformation applied between them.
Check the ground plane, level datum and building placement. If the building is offset or rotated, even a correctly calculated solar azimuth will cast shadows in the wrong direction relative to roads and neighbouring façades. Do not infer north from an attractive aerial photograph unless its orientation is independently established.
For a BIM/CAD visualisation handover, ask for a single approved orientation reference and the current design revision. If the scene has been manually rotated for composition, distinguish that rotation from the site coordinate system in the handover notes.
A clock time without a date and time zone is not a reproducible lighting setting.
Record the calendar date, local civil time, named time zone and UTC offset on that date. Daylight-saving changes mean the same displayed clock time can represent a different instant in winter and summer. If your rendering software accepts only a numerical offset, check it against the intended date rather than copying today's offset.
Solar azimuth describes the sun's compass direction; solar elevation describes its angle above the horizon. These are the quantities to compare across tools. They are not the same as the direction of a warm key light added by eye. Use a trustworthy solar-position method, such as the Solar Position Algorithm maintained by the National Laboratory of the Rockies (formerly NREL), to cross-check an important date-specific setup.
For a presentation brief, it is usually sufficient to log the inputs and the calculated sun direction. For a formal assessment, agree on the approved calculation and model-validation method with the responsible specialist; a generic online calculator is not a compliance certificate.
These are fictional field labels, not a real project, location, calculated solar result or claim about sunshine.
Choose lighting scenarios to answer questions, not to fill a gallery.
One carefully chosen view may explain an entrance, while another may need a different time to show the same space's depth. But a gallery of apparently simultaneous views should not silently combine incompatible sun directions. When images use different dates or times, keep the metadata with each image.
| Scenario | What it can communicate | What it cannot establish alone |
|---|---|---|
| Illustrative warm afternoon | Material character, mood and visual hierarchy | Actual hours of sun on a terrace |
| Specified date and time | Shadow geometry under stated model assumptions | Year-round daylight or legal compliance |
| Several agreed time points | How shadow extents change between those instants | Continuous exposure between samples |
| Specialist simulation | Defined metrics under a documented method | Anything outside its scope, assumptions or validation |
Do not present a solstice snapshot as a typical day, or a clear-sky condition as guaranteed weather. If a proposal is still changing, record which design version each scenario uses so a revised balcony or parapet does not quietly invalidate an earlier image.
The most convincing sun setup fails when the surroundings are missing.
A sun path may be correct and the result still misleading if neighbouring buildings, terrain, retaining walls, deep reveals, balcony slabs or mature trees are absent. The sun does not know whether a wall has been hidden in the scene to improve the composition. Review the shadow-casting geometry separately from the visible decorative context.
Prioritise the elements that materially affect the space being discussed. A distant tower may matter for a low winter sun; a small projecting canopy may dominate an entrance at midday. Distinguish surveyed existing context from simplified massing, assumed future buildings and optional landscaping. If planting is provisional, avoid depicting it as a precise shadow screen. For a more complete landscape brief, see the planting accuracy checklist for architectural renderings, which distinguishes existing trees, specified planting and illustrative greenery.
Use a neutral diagnostic render before adding atmosphere. Display a clear sun direction, simple materials and visible shadow boundaries. Check whether the geometry generating the shadow is actually present and correctly located. If the scene is a photomontage, also follow the camera-matching and occlusion checklist; perspective alignment and solar alignment are separate tests.
Keep solar geometry separate from exposure, colour grading and artistic lights.
A shadow can be physically located yet visually weakened by fill lighting, ambient occlusion settings, denoising, fog or local retouching. Conversely, contrast adjustments can make a small shaded area look much darker than it would under the chosen sky condition. These choices can be valid for a marketing illustration, but they must not be mistaken for measured daylight evidence.
Keep a neutral sun-only or diagnostic pass when the exact shadow boundary matters. Then build the aesthetic treatment as a separate, reviewable layer. Do not move the virtual sun to make a façade brighter while retaining a label that claims a fixed date and time. If an art-directed light replaces the calculated sun, change the description to an illustrative scene.
Interior images deserve the same caution. A sun patch on a floor depends on window dimensions, glazing, reveals, shading devices and nearby obstructions, not merely on an attractive beam of light. A rendered bright room is not a substitute for a daylight-factor or climate-based daylight analysis.
For before-and-after views, freeze the camera and all comparison variables.
To compare an existing condition and a proposal, use the same viewpoint, crop, focal length, date, time, sky model and exposure convention unless the approved methodology explicitly requires otherwise. Otherwise, a change in camera or tone mapping can be mistaken for a change caused by the building.
Record whether shadows come from the proposed building, the surrounding context or both. Show enough of the ground and adjacent façades to understand the change. When comparing two design options, use the same contextual model and sunlight assumptions. If the options have different model revisions or missing elements, state the limitations rather than calling the images directly comparable.
Where quantitative impact is important, a specialist should define comparison metrics, spatial sampling, time intervals and required evidence. A pair of still images, however precise-looking, cannot prove annual sunshine duration or satisfy every jurisdiction's assessment criteria.
Review sun direction and shadow shape before approving the mood.
In the first review pass, hide people, planting flourishes and decorative light effects. Confirm true north, source coordinates, sun angles, the model revision and the largest shadow-casting objects. Then compare a diagnostic shadow pass with the final image. If a shadow changes position between passes, investigate before accepting the final retouch.
In the second pass, review material response and atmosphere: highlights, colour balance, reflections and how the proposed architecture reads. Use the rendering feedback checklist to record whether a comment is a geometry correction, a lighting assumption or an artistic preference. Those categories should not be bundled into “make it more realistic”.
This is a fictional example of a review record, not a documented client issue or performance result.
Label what is verified, what is provisional and what is illustrative.
A public-facing caption can be short without being evasive. For a purely artistic scene, “Architectural visualisation; lighting, planting and finishes are illustrative” is more accurate than “Sunny terrace at 4 pm” when the latter has not been checked. For a genuinely time-specific image, include the date, time, site and design-revision assumptions in the accompanying documentation.
Keep source files and sun settings alongside the approved exports. If a neighbouring building or balcony changes later, the old image may need review. The rendering change-control guide explains how to track and replace images after design revisions. On a development website, match the image caption to the approved project information, not to marketing copy written months earlier.
Do not reuse a time-specific rendering as evidence for a different season or location. If a client requests a new atmosphere, make a separate export and preserve the original documented setup. That small discipline protects both the design discussion and the credibility of the published project.
Sun-and-shadow sign-off checklist.
- The intended use is labelled as illustrative, time-specific or specialist assessment input.
- Latitude, longitude, site datum and true-north reference come from identified sources.
- Model orientation and any scene rotation are recorded.
- Calendar date, local time, named time zone and UTC offset are checked together.
- Solar azimuth and elevation have been cross-checked when the image makes a time-specific claim.
- Shadow-casting buildings, terrain, canopies and other relevant context are present or their omissions disclosed.
- Diagnostic shadows agree with the final rendering's geometry.
- Artistic lighting, exposure and post-production are not represented as measured results.
- Comparison views use consistent cameras, models and lighting assumptions.
- Provisional design, landscaping and context are labelled as such.
- Every export has a view ID, source-model revision and documented approval status.
- The actual desktop, mobile and print crops preserve any information needed to interpret the shadows.
For specialist studies, append the required local method, calculation settings, validation evidence and qualified reviewer approval. This production checklist supports a trustworthy visualisation brief; it does not replace that work.
For further technical background, consult the solar-position research report. The goal is not to make every architectural image scientific. It is to know when an image is an illustration and when its lighting carries a factual claim.