Interior visualisation: SketchUp, 3ds Max and rendering

In short

Interior visualisation is the process of building a 3D model of a space, applying materials and lighting to it, and computing photorealistic images, panoramas or walkthroughs that let a client approve a design before money is spent on site. SketchUp is the fast conceptual modeller, 3ds Max (with V-Ray or Corona) is the industry's high-end rendering platform, and Lumion, Enscape and Twinmotion are real-time engines used for quick client-facing views. B.Des and B.Sc Interior syllabi examine it as a studio-plus-viva subject (modelling exercises, material and lighting studies, render submissions) and it is the single most portfolio-weighted skill in Indian interior hiring - Livspace, HomeLane, Design Cafe, Pepperfry Studio, Godrej Interio, Sleek, Asian Paints Beautiful Homes, Morphogenesis, Edifice and thousands of city-level turnkey contractors test it in a live software round. Rendering is not decoration: the view a client signs becomes the reference against which the executed site is measured.

Explained

Where visualisation sits in the interior workflow

• Brief → mood board → concept → 3D model → materials and lighting → render → client approval → working drawings → BOQ → execution. Visualisation closes the approval gate; drawings and BOQ come after.
• Deliverables, in order of cost: clay/white model views (form only), mood boards with material swatches, still renders (3-6 per room), 360° panorama, VR walkthrough, animated walkthrough.
• Resolution convention: screen approval at 1920×1080; print or competition boards at 3000-4000 px on the long side (roughly 300 dpi on an A4 image; A3 at 300 dpi needs about 4960 px on the long side).
• Camera rule: interiors are shot at eye level 1200-1500 mm above floor with a wide lens (18-24 mm equivalent, ~35 mm film back) and the camera kept level, because a two-point perspective with vertical verticals reads as architecture; a tilted camera reads as a snapshot.
• A render is a representation, not a certification. Finishes, colours and lighting levels must be confirmed against actual samples and the electrical layout, and the drawing set governs execution.

SketchUp: modelling for interiors

• Nature of the modeller: a surface (polygon) modeller - edges and faces, not solids with history. Fast, forgiving, weak on curvature and on parametric change.
• Core tools: Line, Rectangle, Circle, Arc, Push/Pull, Follow Me (sweep a profile along a path - cornices, skirting, mouldings), Offset, Move/Copy, Rotate, Scale, Tape Measure (also rescales a model), Protractor, Paint Bucket, Section Plane.
• Inference engine: on-axis locks (red/green/blue), endpoint, midpoint, intersection and parallel/perpendicular inferences; typed dimensions after a tool stroke (e.g. draw then type 3000,600) are how accurate modelling is actually done.
• Groups vs components: a group isolates geometry; a component is an instance - editing one updates all copies, so chairs, doors, windows and modular carcases must be components. Components also keep the file light and support "make unique" for a one-off variant.
• Layers are now Tags (SketchUp 2020 onward): tags control visibility only, geometry still lives on Untagged inside groups - a common exam/viva point.
• Scenes store camera, style, tag visibility, shadow and section settings; scenes are the basis of animation export and of LayOut viewports.
• Styles: edge/profile/sketchy settings for presentation; Section planes cut live sections and are used to show a room interior from outside and for sectional elevations.
• LayOut: SketchUp's paper-space companion - places model viewports on a titled sheet at a stated scale, adds dimensions and labels, exports PDF/DWG for the drawing set.
• Interoperability: import DWG (plan underlay), export DWG, 3DS, FBX, OBJ, DAE, IFC (Pro), STL for 3D print; 3D Warehouse for furniture blocks, Extension Warehouse for plugins.
• Key interior plugins: 1001bit Tools, Profile Builder, JointPushPull, CurviLoft, Fredo6 (RoundCorner, Tools-on-Surface), SketchUV, Artisan, CleanUp³ (purge and fix), Skatter (grass/scatter), Vertex Tools.
• Model hygiene: purge unused components/materials, avoid huge downloaded blocks with 500k faces, keep geometry inside groups, model at real scale in mm, keep the origin at a building reference point.
• Limitations: no native parametric history, no schedules/quantities, coplanar-face and leaky-solid problems, heavy models slow in large layouts, UV control weak without a plugin.

3ds Max: the high-end pipeline

• Nature: a full DCC package - polygon/NURMS modelling, modifier stack, materials, lighting, cameras, animation, particles, hair, cloth.
• Modelling methods: Editable Poly workflow (extrude, bevel, chamfer, bridge, inset, connect, swift loop), Turbo/OpenSubdiv smoothing, splines + Extrude/Lathe/Sweep/Loft for mouldings and turned legs, Boolean/ProBoolean, Shell for thickness, Editable Patch/NURBS for organic form.
• Modifier stack: non-destructive, order-dependent list on an object (e.g. Bend above Taper ≠ Taper above Bend); collapse only when finished. Common interior modifiers: Shell, Symmetry, FFD, Cloth/Garment Maker (curtains, bedding), Hair & Fur (rugs), UVW Map, Unwrap UVW.
• Scene units: set System Unit = millimetre and display units to mm before importing - the classic blunder is a model imported at 1 unit = 1 inch, which makes every light and every blur-radius value physically wrong.
• Cameras: Physical Camera (focal length, f-stop, shutter, ISO, white balance, exposure, DOF, vignetting) is the standard for interiors; Target camera for simple setups. Enable Safe Frames and set the render aspect before composing.
• Pipeline with SketchUp: model/concept in SketchUp → export FBX/OBJ (or import the .skp directly) → in Max, re-group, assign material IDs, fix smoothing and normals, remodel details → light and render.
• Other modellers used in India: Blender with Cycles/EEVEE (free, rising fast), Rhino + Grasshopper, Cinema 4D, and Revit/ArchiCAD models imported for rendering.
• Limitations: steep learning curve, licence cost, heavy hardware need, long render times, and scene breakage when assets move (use Asset Tracking and relative paths).

Materials, texturing and UV mapping

• PBR (physically based rendering) describes a surface by physical quantities so it behaves correctly under any light: Base colour / Albedo, Roughness (or Glossiness), Metalness, Normal, Bump, Displacement, Reflection (IOR), Opacity, Ambient Occlusion.
• Metal/rough vs spec/gloss workflow: the metal-rough set (albedo + metalness + roughness) is the game/real-time standard; V-Ray and Corona use a reflective layer with IOR and roughness - the same physics, different inputs.
• Typical IOR values: glass ≈ 1.5-1.52, water ≈ 1.33, plastic ≈ 1.46-1.5, polished wood/lacquer ≈ 1.5, ceramic ≈ 1.5-1.7, metals use a complex IOR and are set by metalness = 1 with a coloured reflection.
• Roughness read: mirror ≈ 0, polished granite ≈ 0.05-0.1, semi-gloss laminate ≈ 0.2-0.3, matte paint ≈ 0.6-0.8, fabric ≈ 0.8-1.0.
• Texture mapping types: planar, box, cylindrical, spherical, face, shrink-wrap; UVW Map sets a projection, Unwrap UVW flattens and edits UVs; tiling (U/V repeat), offset and rotation control pattern scale.
• Real-world scale is mandatory: a 600×600 vitrified tile texture must be mapped at 600×600 mm, a brick at ~230×75 mm, a 1200 mm laminate pattern at its real repeat. Wrong tiling is the fastest way to make a render look fake.
• Triplanar / box mapping avoids unwrapping for architectural surfaces; displacement for real grout depth and carpet pile, bump/normal for cheap surface relief.
• Seams and tiling artefacts: use seamless textures, break visible repetition with a colour-correct/noise layer, randomise wood plank UVs (MultiTexture / Corona UvwRandomizer).
• Indian material library a fresher is expected to build: vitrified and ceramic tile, Kota and Kadappa stone, granite and marble (Makrana, Rajnagar, Jaisalmer), Indian teak/rubberwood/sheesham veneers, HPL laminate (Merino, Greenlam, Century), PU and duco paint, Asian Paints/Berger shade cards, MS and SS sections, jute and cane, terrazzo/IPS.

Lighting and rendering engines

• Global illumination (GI): light bouncing off surfaces. Interiors are GI-dominated - most of what you see is indirect, which is why interior renders are slower and noisier than exteriors.
• GI methods: Brute force / path tracing (unbiased, accurate, noisy, slow), Irradiance map + light cache (interpolated, fast, can flicker in animation), photon mapping, radiosity. Still images often use IM+LC; animations use brute force + light cache for flicker-free results.
• Biased vs unbiased: biased engines interpolate and approximate for speed; unbiased engines converge to the true solution with noise reducing as samples rise.
• Light types: area/plane lights (soft, for windows, cove and panel lights), IES lights (manufacturer photometric file - real beam shape of a downlight, available from Philips/Signify, Wipro, Havells, Jaquar, Crompton), spot, point/omni, dome (HDRI), sun+sky, mesh/emissive light, portal light at the window opening to guide samples.
• Photometric units: lights are set in lumens (lm), candela (cd) or lux, not arbitrary multipliers. Colour temperature: 2700-3000 K warm white (living/bedroom), 4000 K neutral (kitchen/office), 5000-6500 K cool/daylight. CRI above 80 matters for showing true finish colour.
• Exposure: the Physical Camera's EV combines f-stop, shutter and ISO; set exposure first, then tune light intensities, never the reverse.
• Engine landscape:
  • V-Ray (Chaos) - Max, SketchUp, Rhino, Revit, Blender; most used in Indian studios; V-Ray Vision for real-time preview.
  • Corona Renderer (Chaos) - very easy exposure/material model, interactive rendering, strong for interiors.
  • Arnold - bundled with Max/Maya, film-oriented.
  • Cycles/EEVEE in Blender - free, path tracer plus a real-time raster/ray engine.
  • Lumion, Enscape, Twinmotion, D5 Render, Unreal Engine - real-time: seconds per view, live links to SketchUp/Revit, excellent for walkthroughs and client meetings; slightly less control over fine material detail than offline engines.
• Denoising: NVIDIA OptiX, Intel Open Image Denoise, V-Ray/Corona denoisers - cut render time hugely but can smear fine texture; render with enough samples that the denoiser only cleans, not invents.
• Render elements / passes: Diffuse, Reflection, Refraction, GI, Lighting, Specular, AO, Z-depth, Cryptomatte/Object ID, Alpha - composited and colour-corrected in Photoshop/After Effects/Nuke. A pass-based workflow lets a client's "make that wall warmer" be fixed in minutes instead of a re-render.
• Post-production: levels/curves, white balance, bloom and glare, chromatic aberration, vignette, sharpening, LUT; entourage (plants, art, crockery) and sky replacement.
• Animation basics: 25 fps (PAL/India broadcast convention) or 30 fps; a walkthrough camera moves on a path or bezier spline at a walking pace; render frames as image sequence (EXR/PNG), never straight to a single video file.
• Hardware: render time scales with CPU cores for CPU engines (Corona, classic V-Ray CPU) and with GPU/CUDA-RT cores for GPU engines (V-Ray GPU, Cycles, Omniverse, Lumion needs a strong GPU and VRAM). Render farms / cloud (Chaos Cloud, Ranch, Indian farm services) are billed per GHz-hour or node-hour.

Standards, codes and legal practice in India

• National Building Code of India, 2016 (NBC 2016, BIS, with 2020-24 amendments) - Part 8 Building Services Section 1 covers lighting and natural ventilation; it is the reference for daylight factor and illuminance expectations in habitable rooms.
• Illuminance practice (SP 72, National Lighting Code and NBC Part 8): indicative maintained lux - general living 100-150, bedroom 100-150 with 300 at the dressing/reading point, kitchen counter 300-500, study/office desk 300-500, retail display 500-750, detailed task areas higher. Treat these as indicative and confirm the current edition's table for an exam answer.
• ECSBC 2024 (Energy Conservation and Sustainable Building Code, which succeeds ECBC 2017) governs lighting power density and controls for commercial interiors above the applicable connected-load threshold; relevant when a visualiser is asked for a compliant lighting layout.
• Electrical safety: the CEA (Measures relating to Safety and Electric Supply) Regulations, 2023 (superseding the 2010 Regulations) and IS 732 for wiring practice govern the actual installation the render implies.
• Drawing conventions for the related drawing set follow the BIS technical-drawing standards (sheet sizes A0-A4, line types, scales such as 1:50 and 1:20 for interiors).
• Furniture and fittings: Indian Standards exist for furniture dimensions and for plywood/blockboard/laminate grades (for example BWP/BWR grade marking on plywood) - quote a grade or subject by name unless you are certain of the IS number and edition.
• Copyright and licensing: drawings, models and renders are "artistic works" under the Copyright Act, 1957; authorship normally rests with the creator but work made under a contract of employment vests in the employer unless agreed otherwise - so a studio owns its visualiser's renders. Downloaded 3D models, HDRIs and textures carry their own licences (CC0, royalty-free, editorial-only); using a pirated asset or a cracked V-Ray licence in client work is an infringement and a real commercial risk.
• Contract practice: the client-approved render is usually annexed to the agreement; a "render vs reality" disclaimer and an approved material and finish schedule are standard protection. GST on interior design/visualisation services is at the standard services rate under the current slab structure (5%/18%/40% since 22 September 2025; design services fall in the 18% band).
• Professional bodies: Institute of Indian Interior Designers (IIID) and the Council of Architecture for architects (the Architects Act, 1972 protects the title "architect", not interior design practice).

Key points

• SketchUp - surface/polygon modeller, fastest concept-to-model tool; accurate only if you type dimensions.
• Component vs group - a component is an instance (edit one, all update) and keeps file size down; a group is just isolated geometry.
• Tags, not layers - tags control visibility only; geometry still belongs to Untagged inside groups.
• Follow Me - sweeps a profile along a path; the tool for cornices, skirting and mouldings in SketchUp.
• LayOut - SketchUp's sheet-layout module for scaled viewports, dimensions and PDF drawing sets.
• Modifier stack (3ds Max) - non-destructive and order-dependent; collapse only when the form is final.
• System units - set to millimetre before modelling or importing; wrong units break lights, DOF and blur radii.
• PBR maps - base colour, roughness, metalness, normal, bump, displacement, opacity, AO.
• IOR - index of refraction controlling reflection strength; glass ≈ 1.5, water ≈ 1.33, most plastics ≈ 1.46-1.5.
• Real-world UV scale - map a 600×600 tile at 600×600 mm; wrong tiling is the top tell of an amateur render.
• GI - indirect bounced light; interiors are GI-dominated, hence slow and noisy.
• IM + light cache fast for stills; brute force + light cache for flicker-free animation.
• IES light - manufacturer photometric file giving a luminaire's true beam distribution.
• Physical camera - focal length, f-stop, shutter, ISO, white balance; set exposure before tuning lights.
• Colour temperature - 2700-3000 K warm, 4000 K neutral, 5000-6500 K daylight; CRI > 80 for true finish colour.
• Render elements/passes - let colour and reflection be fixed in post instead of re-rendering.
• Real-time engines (Lumion, Enscape, Twinmotion, D5) - seconds per view, live model link, ideal for client walkthroughs.
• NBC 2016 Part 8 / National Lighting Code and ECSBC 2024 - the Indian references for illuminance and lighting energy in interiors.

Formulas and examples

Example 1 - how many downlights for a living room (lumen method). A 4.5 m × 3.6 m living room needs an average 150 lux. Luminaires: 12 W LED downlights at 1000 lm each. UF = 0.55, MF = 0.8.

• Area A = 4.5 × 3.6 = 16.2 m².
• Required lumens on the floor = E × A = 150 × 16.2 = 2430 lm.
• Lamp lumens needed = 2430 / (UF × MF) = 2430 / 0.44 = 5522.7 lm.
• N = 5522.7 / 1000 = 5.52 → 6 downlights (a 2 × 3 grid).
• Delivered average = (6 × 1000 × 0.55 × 0.8) / 16.2 = 2640 / 16.2 = 162.9 lux - above the 150 lux target, so acceptable.
• Connected load = 6 × 12 = 72 W → lighting power density = 72 / 16.2 = 4.44 W/m², comfortable for a residential interior.

Example 2 - IES downlight on a table (inverse square law). A downlight of 1200 cd peak intensity is fixed 2.4 m above the floor over a dining table whose top is 0.75 m above the floor.

• Vertical distance d = 2.4 − 0.75 = 1.65 m.
• E = I / d² = 1200 / (1.65²) = 1200 / 2.7225 = 440.8 lux directly under the light.
• Move the fixture to d = 2.0 m: E = 1200 / 4 = 300 lux - a 21% increase in distance cut the light by about 32%.

Example 3 - camera lens choice for a small bedroom. A 3.0 m × 3.6 m bedroom is to be shown from a corner; the camera has a 36 mm sensor.

• With a 24 mm lens: FOV = 2 × arctan(36 / (2 × 24)) = 2 × arctan(0.75) = 2 × 36.87° = 73.7°.
• With an 18 mm lens: FOV = 2 × arctan(36/36) = 2 × 45° = 90°.
• The 18 mm shows more of the room but stretches furniture at the frame edge; 24 mm is the usual interior compromise, and anything below 16 mm distorts badly.

Example 4 - render time and a deadline decision. A 3000 × 2000 still needs 400 samples per pixel. The workstation delivers 2.5 million samples per second.

• Pixels = 3000 × 2000 = 6,000,000; total samples = 6,000,000 × 400 = 2.4 × 10⁹.
• Time = 2.4 × 10⁹ / 2.5 × 10⁶ = 960 s = 16 minutes per view. Six views = 96 minutes ≈ 1 h 36 min.
• Print check: at 300 dpi the 3000 px side = 3000/300 = 10 inches = 254 mm, so it prints clean up to A4 width and is marginal on A3.

Example 5 - walkthrough animation budget. A 40-second walkthrough at 25 fps, 1920 × 1080, 3 minutes per frame, on a 4-node farm.

• Frames = 40 × 25 = 1000 frames.
• Single machine = 1000 × 3 = 3000 min = 50 hours.
• On 4 nodes = 50 / 4 = 12.5 hours (ignoring queue overhead).
• If a real-time engine renders the same frame in 6 seconds: 1000 × 6 = 6000 s = 1 h 40 min on one machine - the reason client-stage walkthroughs are made in Lumion/Enscape and only hero stills are rendered offline.

Where it is used

• Turnkey home interiors: Livspace, HomeLane, Design Cafe, Bonito, Interior Company - visualisers produce 3D views of modular kitchens and wardrobes in SketchUp or in-house configurators, often same-day for a sales meeting.
• Architecture and design studios: Morphogenesis, Edifice, Sanjay Puri, Hafeez Contractor, Studio Lotus and mid-size city firms use 3ds Max + V-Ray/Corona for competition boards and client presentations.
• Dedicated visualisation houses and freelancers: render-only studios serving Indian and overseas architects (per-view pricing, typically a few thousand rupees for a residential still to much higher for hospitality hero shots, varying widely by city and studio).
• Retail, hospitality and real estate marketing: showroom and hotel mock-ups, builder sample flats, brochure and website CGI, 360° panoramas and VR booths at property expos.
• Product and furniture industry: Godrej Interio, Featherlite, Durian, Nilkamal, Asian Paints and Jaquar use CGI catalogues instead of photo shoots; Pepperfry and Urban Ladder list rendered product images.
• Job roles: 3D visualiser, architectural/interior rendering artist, modular design executive, BIM-visualisation coordinator, CGI artist in a game/XR studio; common software test in the interview is "model and render this 10 × 12 ft bedroom in two hours".

Interview questions

• Q: What is the difference between a group and a component in SketchUp? A: A group isolates geometry as a single editable object; a component is a reusable instance, so editing one copy updates all of them and the file stays lighter.
• Q: Why do interior renders take longer than exteriors? A: Interiors are lit mainly by indirect bounced light, so the global-illumination solution needs far more samples to converge, and light entering through small window openings is hard to sample.
• Q: Which GI settings would you use for a still and which for an animation, and why? A: Irradiance map plus light cache for a still because interpolation is fast; brute force plus light cache for animation because interpolated GI flickers between frames.
• Q: What is an IES file and why use it? A: A manufacturer's photometric data file describing a luminaire's real intensity distribution, so the render shows the actual beam shape and scallops instead of a generic cone.
• Q: What does IOR control, and what value would you use for glass? A: Index of refraction - how light bends and how strongly a surface reflects at different angles; about 1.5 for glass, 1.33 for water.
• Q: How do you make a 600 × 600 tile look right in a render? A: Map it at real-world scale 600 × 600 mm with correct tiling, add a slight roughness variation and a grout bump or displacement, and randomise or colour-vary the texture to break visible repetition.
• Q: Why set system units to millimetres before importing a model? A: Light intensities, depth of field, blur radii and displacement amounts are all physical distances; a wrong unit scale makes them meaningless even if the geometry looks right.
• Q: What camera height and lens do you use for an interior view? A: Eye level around 1200-1500 mm with a level camera and an 18-24 mm equivalent lens; wider than about 16 mm distorts furniture at the edges.
• Q: What are render elements and how do they save time? A: Separate passes such as reflection, GI, AO and Z-depth; a client's colour or reflection change can be fixed in compositing rather than by re-rendering the whole image.
• Q: When would you choose Enscape or Lumion over V-Ray? A: When speed and live model linkage matter more than micro-material control - early client meetings, many revisions, walkthroughs and VR; offline engines stay for hero stills.
• Q: Your render looks grainy near the ceiling cove. What do you check? A: Light sample subdivisions and GI samples on the cove light, light-cache resolution, excessive glossiness noise, and whether the denoiser is masking rather than resolving the noise.
• Q: Does a client-approved render guarantee the finish on site? A: No - it is a representation; execution follows the drawing set and the approved material and finish schedule, so physical samples must be signed off separately.

Common mistakes

• Modelling without typed dimensions or at the wrong unit scale, so the model cannot drive drawings or a BOQ.
• Leaving textures at default tiling - giant bricks, tiny tiles, stretched wood - the first thing a reviewer notices.
• Over-bright "multiplier" lighting instead of real photometric values, then burning out the image and claiming "artistic choice".
• Tilting the camera up or down, or using a 10-12 mm lens, producing converging verticals and distorted furniture.
• Using interpolated GI for an animation and delivering a flickering walkthrough.
• Importing 3D Warehouse furniture with hundreds of thousands of faces and never purging, so the file becomes unusable.
• Over-denoising and over-sharpening in post until textures look plastic; and quoting illuminance or ECSBC requirements from memory instead of checking the current edition's table.

Related topics

CAD, Revit and BIM for architects · Estimation and BOQ for interior projects · Lighting design and luminaire selection · Materials and finishes for interiors · Perspective, colour theory and presentation drawing · Modular furniture and joinery detailing