Samples and bounces, settled

Arshvista — Architectural visualisation: render | arshvista.com

A clean interior still in Blender Cycles usually needs 64–128 samples with denoising and 4–8 diffuse bounces — not the 4096-sample default. This reference lays out the numbers that decide whether a render looks photographic or plastic, what they cost in render time, and how to read the failures when something looks wrong.

Key values for a clean interior archviz render in Blender Cycles
Setting	Working value
Final samples, denoised still	64–128 samples
Denoising floor	≈32 samples
Diffuse bounces	4–8
Glossy bounces	2–4
Exposure, daylit interior	−0.7 to −0.3 EV
Exterior plate strength	0.2–0.5
Focal length, full-frame equivalent	8–24 mm
Delivery resolution	2000–4000 px long edge

Terms used on this page

Sample: One light path traced through a pixel; averaging more samples cancels Monte Carlo noise. Cycles ships with a 4096-sample default for final renders and 1024 for viewport previews.
Diffuse bounce: One redirection of light off a matte surface. Interiors need 4–8; dropping to 1–2 is the most common cause of black corners in a room render.
OpenImageDenoise: The denoiser bundled with Blender. With the Albedo and Normal passes enabled it cleans an interior still at 64–128 samples; below roughly 32 samples it smears fine texture.
Stop (EV): A halving or doubling of scene brightness. A correctly exposed daylit interior typically lands between −0.7 and −0.3 EV after white balance.
IES LM-63: A photometric file format that records luminous intensity on a 1-degree vertical grid (up to 100 angles) and a 10-degree horizontal grid (up to 10 angles).
View transform: The mapping from scene-linear light to display colour. AgX replaced Filmic as Blender's default in version 4.0 (2023); Filmic had held the role since 2.80 (2018).

The short answer

64–128 samples with denoising, 4–8 diffuse bounces and 2–4 glossy bounces — that is the whole preset for most interior stills.

Cycles ships with 4096 samples for final renders and 1024 for viewport previews. Those defaults are written for worst-case scenes — caustics, heavy volumetrics, deep indirect light — and treating them as a target is how a still that should take minutes turns into an overnight job.

With the OpenImageDenoise denoiser and its Albedo and Normal passes enabled, 64–128 samples is usually enough for an interior still. The denoiser uses those auxiliary passes to tell surface detail apart from shading noise, which is why the passes matter as much as the sample count itself.

Bounces are the second half of the preset. Typical interior counts are 4–8 diffuse and 2–4 glossy; the diffuse value carries indirect light into corners, and the glossy value keeps reflections alive on metal and glass.

Step 1 — set final samples to 128 and enable OpenImageDenoise with the Albedo and Normal passes; on a current GPU a 1920×1080 frame at this level finishes in minutes.
Step 2 — set diffuse bounces to 4 and glossy to 2; if the black-corner failure appears, raise diffuse toward 6–8 before adding a single sample.
Step 3 — render a crop at 64 samples and inspect hair, foliage and fabric; if the denoiser-smear failure shows, the frame is near the 32-sample floor, so raise samples rather than denoiser strength.
Step 4 — check exposure: a daylit interior should land between −0.7 and −0.3 EV after white balance; if the blown-window failure appears, cut the exterior plate to 0.2–0.5 scene strength.
Step 5 — only if noise survives all of this, raise samples toward 512; expect a few to a few tens of minutes per 1080p frame, and treat 4096 undenoised samples, at 20–60 times longer, as a last resort.

How the defaults shifted

The view-transform change matters because exposure habits built on Filmic do not transfer one-to-one to AgX.

Timeline: 3 dated entries

Why the 4096-sample default is the wrong starting point

The shipping default is a ceiling for pathological scenes, and render time scales almost linearly with sample count.

A 1920×1080 interior still at 512 samples with denoising takes from a few minutes to a few tens of minutes on a current GPU. The same scene at 4096 samples without denoising runs 20–60 times longer — the difference between an afternoon of iterations and a queue you check in the morning.

Because time scales with samples, every doubling costs a doubling of minutes but buys less visible improvement once the denoiser has enough signal to work with. The skill is finding the floor where the denoiser still behaves, not climbing toward the default.

Viewport previews default to 1024 samples, which is why the interactive view can look cleaner than a low-sample final render with denoising switched off — the two numbers answer different questions.

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The denoising floor: where 32 samples stops working

Below about 32 samples, OpenImageDenoise stops removing noise and starts inventing texture.

The denoiser needs enough traced paths to separate signal from grain. With the Albedo and Normal passes enabled it can distinguish shading noise from genuine surface detail, which is exactly what makes the 64–128 sample range viable for an interior still.

Below roughly 32 samples that separation fails. Fine texture — hair, foliage, fabric weave — is smeared into watercolour blotches, and no extra denoiser strength brings it back, because the information was never traced in the first place.

The practical reading: if a render looks painted rather than photographic, the fix is samples, not a different denoiser. Raise the count into the 64–128 range and re-render the failing crop before committing to a full frame.