Procedural Islands III: Multi-Scale Noise and Topological Mountains for Final Elevation

The article finalizes island elevation by layering multiple Simplex noise octaves onto a base paint map and adding coastline-specific high-frequency detail. Mountains are shaped by a BFS distance field on the Delaunay mesh using randomized, jagged increments, then blended with hills and coastal elevation for smooth transitions. Elevation is computed per triangle and averaged to Voronoi regions, preparing for hydrology in Part IV.

Key Points

• Enhance the base paint map with six Simplex noise layers at multiple frequencies, focusing high-frequency detail at coastlines via a bell-shaped modulation.
• Compute a mountain distance field using BFS over the Delaunay topology with randomized, triangularly distributed step increments to create organic ridges.
• Shuffle neighbor visitation (Fisher–Yates) to avoid directional bias and promote natural branching in mountain features.
• Blend land elevation from coastal, hill, and mountain components with a quadratic weight; scale ocean depth separately with low-frequency variation.
• Convert triangle-sampled elevations to Voronoi region elevations by averaging the triangles incident to each seed point.

Sentiment

Generally positive toward the article’s approach, with constructive debate advocating more physics-based, process-driven alternatives and hybrid models.

In Agreement

• Approval of the mesh-based (Delaunay) approach as efficient at scale and a thoughtful alternative to grid-based generation.
• Praise for injecting randomized jitter into the BFS distance field to derive more natural mountain shapes.
• Support for the staged, ontogenic pipeline with erosion planned later, balancing realism and practicality.
• Recognition that multifractal/fractal noise methods are a strong foundation for believable terrain detail.

Opposed

• Preference for physics-/geology-driven generation (tectonics, erosion, weather, ocean currents) over noise-centric methods to achieve higher realism.
• Advocacy for teleological approaches and even ongoing simulations where the world continues to evolve over time.
• Presentation of alternative physics-inspired projects (e.g., mg_tectonic) as exemplars of more scientifically grounded terrain.