LaplaceScheduler_motorway_edition

LaplaceScheduler_motorway_edition is the pipe-wrapped version of one of ComfyUI's more obscure noise schedules. Core ships it, it exists in the custom_sampling toolbox, and it computes a sigma schedule shaped by a Laplace (double-exponential) distribution rather than the more familiar Karras or exponential curves. This wrapper changes exactly nothing about the math - it just stores the computed sigmas in a Motorway key instead of emitting them from a socket.

When you'd ever use it

Honest answer: rarely, and that's fine. The mu and beta widgets let you skew the noise distribution - mu (default 0, range −10 to 10) shifts the peak, beta (default 0.5) spreads the tails. It's the kind of knob you reach for when you're hunting for a specific "vibe" in the noise trajectory that the standard schedules don't give you, which is a fringe activity. The KB's sampler guidance is essentially: for SD 1.5/SDXL start from DPM++ 2M Karras, and on modern flow-matching models prefer balanced, conservative schedules. Laplace is not on anyone's "just use this" list, and nothing about the wrapper changes that.

The other widgets are the schedule-generator standard: steps (default 20), sigma_max (14.614642), sigma_min (0.0291675). Defaults exist so the node runs sensibly out of the box, but since mu and beta are the only fields unique to this curve, they're the ones to fiddle with if you're experimenting at all.

Motorway specifics

All inputs here are widgets, so the MOTORWAY 🚌💨 input is optional - unplug it and the node still computes and stores its sigmas. The only key you set is:

• OUTPUT_SIGMAS_key (default "SIGMAS") - where the schedule lands in the pipe.

Output is just the MOTORWAY 🚌💨; read SIGMAS back with a Motorway AxB ramp when a downstream sampler needs it. Nothing else to configure, which is both the appeal and the limitation of this node: it's a single-purpose curve generator that only makes sense inside a pipe-based custom-sampling workflow.

Install and caveats

cd ComfyUI/custom_nodes
git clone https://github.com/agilly1989/ComfyUI_agilly1989_motorway

Restart ComfyUI, or install via ComfyUI Manager. No pip deps, no model downloads.

Two pack-wide warnings before you invest time here. This is an active-development beta by one maintainer - the README warns things break - and right now the repo is mid-refactor with the _motorway_edition node registration commented out, so a fresh clone may not even expose these nodes. If you hit the 'MotorwayClass' object has no attribute 'hash_' error, it means a key you set was never written to the pipe. And a scheduling opinion, not a bug: for most models you want Karras (old SD) or a balanced schedule (new flow-matching), so treat Laplace as a curiosity to try when you're bored, not a default. The stock node is the same code with a socket; this wrapper only earns its place if your workflow is already routing sigmas through keys.