Guide 002 · Beginner
Sliding, Walking and Samples, without the guesswork.
RE+ does not add a fake blur after the frame is finished. It renders the scene at several real moments, then averages those moments into one frame. This guide owns the two motion-blur timing modes, Sliding and Walking. Physical depth of field has its own lens workflow.
NEW TO RE+?Start with the visual beginner courseVideos, diagrams and a complete first-export walkthroughDepthOfField is now a third capture mode, but it does not use RenderSamples this way. Read the separate physical depth-of-field chapter for aperture sampling and autofocus.
The mental model
One output frame can contain many moments.
Imagine photographing a moving car. A short exposure records a small slice of its movement, so the car looks crisp. A long exposure records more of its movement, so the car leaves a longer trail. RE+ recreates that exposure by collecting multiple rendered moments and averaging them together.
RenderFpsHow often a finished frame is delivered
At 24 fps, each output-frame interval lasts 1/24 second.
RenderShutterHow much of that interval is exposed
At 0.5, half of the frame interval is open. That is 180°.
RenderSamplesHow many moments fill that exposure
More moments make the trail less stepped. They do not make it longer.
RE+ documents every sample as a real render at a real instant. It defines 0.5 as a 180° shutter and 1 sample as no accumulated blur.Open source
Interactive example
Change one setting at a time.
Start with 24 fps, a 0.5 shutter and 24 samples. First change only the sample count. The exposure window stays the same size while more sample points fill it. Then change the shutter. The window itself becomes shorter or longer.
RE+ lets the replay keep playing slowly while it collects these samples. Temporal effects keep their history, but the shutter timing is approximate.
The work estimates follow the RE+ source model: Sliding uses samples ÷ shutter engine frames per output frame; Walking uses settle frames + samples × (1 + sub-settle frames).Open source
Capture modes
Sliding keeps time moving. Walking asks for exact times.
Sliding
The clip plays in controlled slow motion while RE+ collects samples. Particles, temporal anti-aliasing, screen-space reflections and ray-traced history keep updating between samples.
- Temporal effects stay warm
- Shutter placement is approximate
- Usually fastest at a 1.0 shutter
Walking
The clip pauses and seeks to the midpoint of every sample. Timing is deterministic, but each seek makes particles and temporal effects begin without their previous-frame history.
- Exact sample midpoints
- Temporal effects reset per sample
- Can win on very short shutters
It is more predictable in time, but it gives up temporal continuity. A result can be mathematically better timed and visually worse if GTA’s particles, TAA, SSR or RT need previous frames.
The behavior, timing trade-off and performance crossover above come directly from the RE+ capture-mode documentation.Open source
Keep the jobs separate
Shutter changes the amount of blur. Samples change how well it is reconstructed.
| Change | What changes | What does not |
|---|---|---|
Samples 8 → 48 | More rendered moments fill the same exposure, reducing stepped or beaded trails | The trail duration and output fps |
Shutter 0.25 → 1.0 | The exposure grows from 90° to 360°, producing a longer movement trail | The number of samples |
Fps 24 → 60 | More finished frames are delivered each second and every frame interval is shorter | The shutter fraction you entered |
Sliding → Walking | How RE+ moves through time between samples | The requested fps, shutter and sample count |
ARRI gives the physical-camera equation as exposure time = shutter angle ÷ (360 × fps). RE+ stores shutter angle as a 0 to 1 fraction, so the same equation simplifies to shutter ÷ fps.Open source
Useful starting points
RE+ explicitly recommends 3 while setting up a shot. It is quick, not final-quality advice.
This is the 180° convention. At 24 fps, the exposure is 1/48 second.
A practical starting range from this guide. Compare a short section before committing a whole render.
The 24 to 48 range is editorial guidance, not an official RE+ requirement. Fast movement and long shutters can need more samples. Slow movement can need fewer.
What should I use?
A simple decision path beats a magic preset.
- 1
Start with Sliding
It is the RE+ default and preserves temporal effects. Use 3 samples for setup, then raise the count for a short final-quality test.
- 2
Judge a moving part, not a still frame
Watch wheels, hands, bright reflections, particles and the edge of the camera move. These reveal uneven sampling first.
- 3
If the timing or smear is wrong, try Walking
Walking is worth testing for short shutters and shots where Sliding produces a bad result. Compare the same few seconds.
- 4
If particles, TAA, SSR or RT break, return to Sliding
That is the expected trade-off, not proof that you configured Walking incorrectly.
RE+ itself recommends Walking when a Sliding render looks wrong or for short shutters, while warning that every Walking sample starts with cold temporal history.Open source
Common myths
Four things to stop telling beginners.
“More samples means more blur.”
False. Shutter determines how long the exposure lasts. Samples only divide and fill that exposure.
“Walking is always the best quality.”
False. It gives exact times, but temporal effects reset. Which mode looks better depends on the shot.
“0.5 means half quality.”
False. It means a 180° shutter: half of each output-frame interval is exposed.
“24 fps means GTA must render at 24 fps.”
False. RenderFps is the delivered output rate. RE+ can run many engine frames and sample captures to build each one.
Read and watch
Sources you can follow beyond this guide.
Capture Modes
The authoritative Sliding vs Walking behavior, formulas and mode advice.
The Renderer
How accumulated samples, output, audio and render duration work in RE+.
Shutter angle and exposure time
A camera-maker explanation of 90°, 180° and 360° shutter timing.
Temporal sampling in a real-time renderer
An official visual guide showing how shutter-open time is sliced into temporal subframes. It explains the general idea, not RE+’s specific implementation.
RE+ implementation claims are checked against the project source and generated configuration, not the README alone. Physical shutter math is tied to ARRI documentation. Epic’s material is included only to visualize the broader temporal-sampling idea. No unofficial video is treated as proof of how RE+ works.