# Research Basis and Known Constraints

## Reference clip

The supplied X post is a Blender look-development reference in which a grey urban blockout becomes a polished city while the core geometry changes very little. The project should adopt that discipline: lock spatial geometry early, then create value through material systems, lighting, atmosphere, decals, vegetation, windows, and controlled detail.

## Historically supported foundation for the concept

The National Park Service describes Yerba Buena Cove as a shallow cove and mudflat that was rapidly filled during the Gold Rush. It states that abandoned ships were buried by sand, dirt, and debris, and that the modern downtown stretch from the Ferry Building to the Transamerica Pyramid occupies the former cove. The NPS identifies the Niantic at Clay and Sansome and the General Harrison near Battery Street, and estimates roughly 40-60 buried ships downtown.

This supports:
- a reconstructed historical shoreline;
- a fill volume;
- ship-specific archaeological layers;
- a visible difference between confirmed wrecks and broader inferred maritime debris.

It does not support:
- inventing exact shapes for all buried ships;
- exact continuous subsurface stratigraphy;
- exact utility or foundation geometry.

## Portsmouth Square

Public 2026 Recreation and Parks documentation says the square includes an underground parking structure and that the renovation will retain the garage, re-waterproof its roof, and seismically upgrade portions of it. It also explains that the garage and natural topography organize the park into upper and lower terraces.

The square is currently in a renovation cycle. The project must declare whether it depicts:
- the pre-2026 square;
- the 2026 construction state; or
- the proposed post-renovation square.

The recommended default for a stable, recognizable cinematic set is the pre-2026 state, with later states as optional variants.

## Model limits

The subterranean model must be presented as an evidence-labeled reconstruction. Public sources can support the existence and approximate spatial relationship of fill, former shoreline, buried ships, garage volumes, and generalized geology. They usually cannot support centimeter-accurate underground geometry.

## Initial web sources

- National Park Service, Buried Ships of San Francisco
- San Francisco Recreation and Parks, Portsmouth Square Improvement Project and 2026 contract documents
- DataSF, Building Footprints
- San Francisco Public Utilities Commission, San Francisco's Changing Shoreline
- U.S. Geological Survey and California Geological Survey elevation, geology, and liquefaction sources
- Blender Python API documentation