Path tracing is a specific kind of ray tracing where the algorithm doesn't just follow rays to compute direct lighting — it follows them through many random bounces around the scene to simulate full global illumination. At each surface a ray hits, the algorithm randomly samples a direction for the next bounce, accumulates the light contribution, and continues until the ray terminates after a set number of bounces or by random chance.
Because path tracing relies on random sampling, the output is noisy at first and converges to a clean image only after many samples per pixel. A high-quality path-traced architectural render can require 1000+ samples per pixel and may take an hour or more even on a powerful GPU. The result, when fully converged, is the closest thing to physically perfect rendering currently available.
Path tracing is the gold standard for offline architectural rendering, used in V-Ray, Corona, Arnold, and most production-grade renderers. AI rendering changed the time-quality trade-off: rather than waiting hours for convergence, an AI model produces a path-traced-quality image in under a minute by learning the patterns of converged renders. The image isn't physically computed, but for architectural marketing and conceptual work it's usually indistinguishable.
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