natural-window-light

SKILL: Natural Window Light

Version: 1.0 | Hermes Agent Lighting System

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DESCRIPTION

Mastery of daylight entering interior spaces through architectural openings. The window acts as a large softbox whose quality varies dramatically by orientation (north/south/east/west), time of day, weather, and diffusion treatment. The foundation of natural light studio photography and classical interior cinematography.

TRIGGER KEYWORDS

window light, natural light interior, soft window, diffused daylight, north light, window portrait, studio window, afternoon light, morning light, backlit window, window glow, sheer curtain light, studio natural

CORE RULES

• North-facing window (northern hemisphere): consistent cool soft light all day — ideal for portraits and products
• East window: warm morning light; West window: warm afternoon light; South: harsh direct midday risk
• Window size equals source softness: larger window = softer wrap, smaller = more directional
• Shadow side is the creative space: fill ratio determines drama vs. beauty
• Curtain/diffusion doubles the effective source size, reduces color temperature slightly
• Camera angle relative to window changes everything: face the window for flat fill, side-on for form
• Dust motes and window bars add visual texture — use intentionally

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TECHNICAL PARAMETERS

Window Direction & Quality:

North Window (Northern Hemisphere):

• Light: Consistent all day, never direct sun
• Quality: Soft, cool, even — ideal as giant softbox
• Color Temperature: 6500K–7500K (cool, blue-shifted)
• Shadow: Open, soft, subtle directionality
• Best For: Portraits, product, still life, consistent sessions

South Window:

• Morning/Afternoon: Indirect, soft, similar to north
• Midday: Direct sun entry (harsh, needs diffusion)
• Seasonal Variation: Extreme (direct in summer, oblique in winter)
• Best For: Direct sun effects when controlled; otherwise diffuse

East Window:

• Morning: Direct hard sun, warm (3500K–4500K), dramatic
• Afternoon: Indirect, soft, cool-neutral
• Best For: Morning portraits with directional warmth; afternoon soft light

West Window:

• Morning: Indirect, soft, cool-neutral
• Afternoon/Evening: Direct warm sun, golden hour quality indoors
• Best For: Afternoon golden light streaming in; warm sunset interiors

Time of Day Progression:

• Sunrise: Hard, warm, low angle, long shadows indoors
• Mid-Morning: Moderate angle, still warm, manageable
• Midday: High angle, neutral-to-cool, top-lighting tendency
• Afternoon: Lower angle, warming, longer shadows
• Golden Hour: Extreme warm, low angle, dramatic streaks across floor
• Blue Hour: Cool ambient, no direct sun, mixed with interior tungsten

Curtain Diffusion Levels:

• No Curtain: Hard directional light, sharp shadows, high contrast
• Sheer Curtain: Soft directional, visible window shape in shadows, moderate contrast
• Opaque Curtain: Very soft, directionless, low contrast (near overcast quality)
• Half-Diffused: Partial curtain coverage creating gradient from hard to soft
• Blinds/Slats: Hard striped shadows (venetian blind effect)

Distance from Window:

• 0–2 ft: Brightest, most directional, highest contrast
• 2–4 ft: Moderate intensity, softer edges, good portrait zone
• 4–8 ft: Dim, very soft, low contrast, background suitable
• 8+ ft: Ambient bounce quality, minimal directionality

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PROMPT ARCHITECTURE

Core Prompt Template:

[Interior] scene lit by natural light through [window type/direction], 
[subject] positioned [distance] from [large/small] window, 
[soft/hard] directional light from [time of day] creating [shadow description], 
[diffusion: sheer curtains/blinds/none] modifying light quality, 
[warm/cool/neutral] color temperature based on [orientation/time], 
light falling across [floor/furniture/subject] in [pattern], 
background interior visible in [exposed/shadow] detail, 
cinematic natural light photography, 
photorealistic interior atmosphere

Negative Prompts:

artificial lighting, overhead lights, studio strobes, 
flat lighting without direction, even illumination, 
wrong time of day for window direction, 
clipped window view, underexposed interior, 
unnatural color temperature, LED look

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ADVANCED TECHNIQUES

1. North Light Portrait (Classic Studio)

• Window: Large, north-facing, floor-to-ceiling if possible
• Subject: 3–4 ft from window, turned slightly toward light
• Quality: Consistent all day, no time pressure
• Background: Falls into soft shadow naturally
• Emotional: Timeless, classical, contemplative
• Historical: Preferred by portrait painters for centuries

2. Morning East Light (Drama)

• Time: 1–2 hours after sunrise
• Quality: Hard, warm, low angle
• Effect: Long shadows across floor, dramatic side-lighting
• Diffusion: None or minimal for maximum drama
• Subject: Profile or three-quarter for sculptural effect
• Emotional: Fresh, awakening, hopeful

3. Golden Hour West Window (Warmth)

• Time: 1–2 hours before sunset
• Quality: Warm (3500K), low angle, directional
• Effect: Light streaks across room, dust visible in beams
• Diffusion: None — let hard sun create pattern
• Subject: Backlit or side-lit with warm glow
• Emotional: Nostalgia, domestic warmth, ending day

4. Sheer Curtain Softbox (Beauty)

• Window: Any direction with strong light
• Diffusion: White sheer curtain fully covering window
• Effect: Giant softbox, soft shadows, flattering skin
• Subject: Close to curtain for softest quality
• Background: Controlled by distance from window
• Emotional: Soft, feminine, ethereal, beauty

5. Blue Hour Mixed (Cinematic)

• Time: 20–40 minutes after sunset
• Window: Cool blue ambient (8000K+)
• Interior: Warm tungsten practicals (2800K)
• Effect: Extreme warm-cool contrast, cinematic color palette
• Exposure: Balance for window view or interior warmth
• Emotional: Melancholy, transition, liminal time

6. Venetian Blind Shadow (Noir)

• Window: Strong direct sun
• Modification: Blinds or slats at angle
• Effect: Hard striped shadows across subject/room
• Emotional: Imprisonment, mystery, film noir
• Control: Slat angle controls shadow width and direction

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WINDOW SETUP QUICK REFERENCE

Direction	Best Time	Light Quality	Color Temp	Diffusion Need
North	All day	Soft, even	6500K–7500K	None/Optional
East	Morning	Hard, warm	3500K–4500K	Sheer for portraits
West	Afternoon	Hard, warm	3500K–4500K	Sheer for portraits
South	Morning/Afternoon	Variable	5500K–6500K	Often required midday

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EXAMPLE PROMPTS

North Light Portrait:

Classical portrait lit by large north-facing window, subject positioned 3 feet from floor-to-ceiling window with soft even illumination, cool 7000K light wrapping gently around face with subtle shadow on opposite side, no direct sun ever entering, background interior falling into soft shadow detail, timeless studio quality, large diffuse catchlights in eyes from window, professional portrait photography, natural skin texture, contemplative mood, painterly north light aesthetic

Golden Hour Interior:

Interior scene at golden hour, warm 3800K sunlight streaming through west-facing window creating long dramatic light streaks across wooden floor, dust particles visible in light beam, subject sitting in warm pool of light with cool shadow side, no curtains creating hard shadow edges, background room in deep shadow with subtle detail, nostalgic domestic atmosphere, cinematic natural light, photorealistic interior, warm-cool contrast between lit and shadow areas

Blue Hour Mixed:

Interior scene during blue hour, cool 10000K twilight leaking through window mixing with warm 2800K tungsten lamp on table, extreme color contrast between blue window light and orange interior glow, subject illuminated by lamp with warm skin tones while background window shows deep blue evening, cinematic mixed lighting, atmospheric interior, realistic light falloff, photorealistic color science, moody transitional time of day

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TECHNICAL NOTES FOR AI GENERATION

• Specify window direction explicitly ("north-facing", "east window") for correct light quality
• Include time of day to justify color temperature and angle
• Mention "curtain" or "sheer" to control hardness
• Use "light streaks across floor" for low-angle sun
• Include "dust in light beam" or "volumetric" for atmosphere
• Specify distance from window ("3 feet from window") for intensity and softness
• Use "background in shadow" to prevent AI from over-lighting interior