Where is Q queried?

Drag time t and the noisy point a_t to see where each of the three guidance gradients queries the Q value.

a_t noisy point — OOD queries here â₁ one-step estimate — QGF queries here ODE(a_t) true endpoint — BPTT queries here

t 0.25

a_t -0.60

â₁ = a_t + v·(1−t)

—

ODE(a_t) true denoising endpoint

—

Is the query point trustworthy?

—

Observe: when t is small, the orange a_t often lands in the red OOD region (Q is untrustworthy), whereas the cyan â₁ and the purple ODE endpoint almost always land on the data peaks (trustworthy). â₁ reaches the data with just one extrapolation step, while the ODE endpoint is the most accurate but requires running the whole chain. Drag t close to 1 and all three points coincide — by then denoising is nearly finished.