Glazing that reads correctly: tint, reflectivity, and what sits behind the glass

Glazing is the first thing a client looks at and almost never the first thing an artist fixes. That is backwards. On a commercial elevation, glass can occupy more than half the frame, so every decision about tint, reflectivity, and interior visibility is a decision about the whole image.

The starting point is accepting that glass is a ratio, not a material. At any given pixel the eye is reading a mix of what reflects off the outer pane and what transmits from inside. That ratio changes with viewing angle. Panels near the camera axis show the interior. Panels at a shallow angle turn into mirrors. If every panel on a facade shows the same amount of interior, the image reads as flat, and no amount of shader polish will recover it.

Tint is where the clichés live. Most default glass presets sit somewhere between aquarium blue and bottle green, and most real architectural glazing is far more neutral than that. Modern low iron units are close to colourless. Standard float with a solar coating usually lands as a faint green or grey, easily under a five percent shift. Push tint until it is obvious and the building starts to look like a nineties office park.

Reflectivity should come from the coating specification, not from taste. Ask whoever is running the project what the visible light reflectance is. A value in the 10 to 15 percent range behaves quite differently from a high performance coating in the 30s, and a facade consultant will notice immediately if the image implies a product the project cannot afford.

The single biggest win in glazing realism is putting something behind the glass. Empty black voids kill a commercial render. You do not need a fully furnished interior for every floor. A ceiling plane, a slab edge, a back wall at the right depth, a row of pendant lights, and one or two blinds pulled down at uneven heights will read convincingly from street level. Vary the blind positions floor by floor. Buildings are used by people, and people are inconsistent.

Interior lighting inside a daylight exterior is a balance question. If the interior sits at daylight brightness the image reads as a night shot layered onto a day sky. Keep interior levels roughly two to three stops under the exterior for a daytime elevation, then reverse the relationship for dusk. For interior practicals visible through glazing, warm sources around 3599K against a cooler exterior dome create the separation the eye expects.

Double glazing means two panes with an air gap, and that gap produces a faint doubling in reflections that photographers see constantly. Modelling two actual surfaces rather than one zero thickness plane captures this and costs very little. It also produces correct behaviour at the edges where the spacer bar sits, which is a detail that quietly lifts close range shots.

Real glass is never clean. Rain trails, dust in the lower corners, faint cleaning arcs on street level shopfronts. Apply this to roughness only, at very low contrast. A uniform, perfect glazing plane reads as CG faster than almost anything else in the frame, and a subtle grime map at three or four percent strength is enough to break it.

Flatness in facade glass is another giveaway. Large panels are never dead flat. Thermal load, wind pressure, and fixing tolerance introduce a gentle bow that makes reflections shift slightly from panel to panel. A very low amplitude noise or bend across the glazing normals, applied unevenly, reproduces that and turns a wall of identical squares into something photographic.

Watch what the glass is actually reflecting. If your context model stops two buildings away, the upper floors will reflect empty sky while the lower floors reflect detail, and the transition will look artificial. Build context wide enough that reflected content stays consistent through the frame, even if that context is low detail massing with a decent texture on it.

Finally, judge glazing on the final graded image rather than in the viewport. Tone mapping changes reflection contrast substantially, and a tint that looked correct in a raw buffer can go heavy after grading. Render a small crop, grade it, and evaluate. That loop takes minutes and saves an entire revision round.