Synthetic Geology

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Synthetic geology

Added three new geological field generators to the optimal sampling framework. The existing channelized and branching models were good for testing the entropy-based sampling algorithms, but they only captured one type of geological pattern. Real mineral deposits have much more variety.

Sampling strategy comparison

New field types

Porphyry copper deposit: Concentric rings with radial veins, mimicking the alteration zones around a copper porphyry intrusion. The center is offset randomly to avoid the algorithm “learning” that the interesting zone is always in the middle.

Vein networks: Thin branching structures generated by random walks with 5% branching probability at each step. These are the hardest for regular grid sampling to capture — the veins are narrow and the information is spatially concentrated along sparse linear features.

Faulted blocks: Angular fault-bounded domains with distinct properties in each block. The faults are linear discontinuities that regular sampling often misses entirely unless a sample happens to land near the boundary.

The sampling question:
Given N measurements, where do you place them to minimize H(Xf | Xf)?
H = posterior entropy. Xf = sampled locations. Xf = unsampled field.

The adaptive entropy algorithm (AdSEMES) should excel on veins — it concentrates samples along high-uncertainty boundaries, exactly where the thin structures are. Regular grids waste most of their budget on empty background.

Also built a comparison page where you can see all field types side by side with different sampling strategies. The visual difference between random sampling and entropy-driven sampling on a vein network is striking.

Information theory concepts

The porphyry generator uses np.sin(r * 0.3) > 0.3 for the concentric rings and np.sin(angle * k) > 0.7 for radial veins, where k is randomly chosen between 3 and 8. Simple trigonometry producing surprisingly realistic-looking alteration halos.

Here’s the adaptive sampling algorithm in action on these fields: