Continuous Flow Matching (Lipman et al.) & Optimal Transport Flow Matching (OT-FM, powering Stable Diffusion 3 and Flux.1) revolutionizes continuous generative modeling by replacing curved stochastic diffusion SDE paths with mathematically minimal straight-line probability trajectories; standard diffusion processes follow curved, chaotic Brownian paths requiring fine-grained numerical integration steps; Flow Matching directly regresses the time-dependent vector field
vt(x) generating continuous probability path
ψt(x0):
LCFM(θ)=E[∥vθ(ψt(x0),t)−ψ˙t(x0)∥2]; under Optimal Transport conditions, the interpolation trajectory from noise
x0∼N(0,I) to data
x1 becomes a
pure straight line:
ψt(x0)=(1−t)x0+tx1, where the target vector velocity field is the constant vector
ψ˙t=x1−x0, enabling 4-10 step ultra-fast generation via simple Euler ODE steps.