# 1893 WCE Administration Building scene This package is the EraWeaver + Qurmmius Palimpsest MVP evidence scene for the Administration Building at the World's Columbian Exposition in Chicago. Its site anchor is the Chicago Park District's current location for the Statue of the Republic, which the District says was installed on the site of the former Administration Building. It is not a georeferenced building footprint. ## What is included - Five Library of Congress source derivatives from distinct viewpoints in `sources/`. - Lossless PNG handoff copies are available in the repository-level `wce-source/` folder for restore/enhance and 3DGS upload workflows. - An AI-assisted inferred-sky candidate in `../../references/loc-1893/` with a separate provenance record. - `scene-manifest.json`, which connects photographs, citations, hotspots, uncertainty, and the future 3DGS asset. - `palimpsest-layer.geojson`, the Chicago Park District's modern memorial-location pin for the reported former building site. It is not a completed building-footprint georeference. - A browser scene page at `/eraweaver/scene/1893-wce/` with evidence gallery, hotspot cards, map view, local `.ply` upload path, and an optional Gaussian Splatting drop-in viewer. ## Reconstruction handoff Run `scripts/reconstruct-wce.ps1` to use the Qurmmius local reconstruction engine. It keeps the photographs on-device, estimates relative poses from overlapping features, triangulates a sparse colored point cloud, and writes `/splats/wce-administration.ply` plus `reconstruction-manifest.json`. The report is consumed by Qurmmius Palimpsest and records confidence, hashes, camera-pose attempts, and uncertainty. It is a reviewable hypothesis, not a surveyed or historically exact model. The repeatable `scripts/build-qurmmius-scene.ps1` command adds a calibrated SfM handoff when `pycolmap` is available. For this WCE source set it selected four overlap-connected views and recovered 355 relative 3D points at 0.50 px mean reprojection error. Open **Inspect calibrated camera solve** on the scene page to review it, or download `/splats/wce-administration-calibrated.ply` and its JSON report. This solve has no absolute scale and remains review-required. The scene also accepts a separately reviewed KIRI, Blender, or other 3DGS export as `.ply` or `.splat` via the model picker. The optional Gaussian Splatting viewer uses `@mkkellogg/gaussian-splats-3d` with `THREE.CSS2DRenderer`; the browser point-cloud fallback remains available when CDN modules are blocked. When CUDA COLMAP is available, the build adds a true dense MVS handoff using GPU PatchMatch stereo, geometric fusion, and Poisson meshing. The current checked-in run uses four overlap-connected views and records its actual fused point/mesh counts in `reconstruction-manifest.json`. Inspect it with `?geometry=dense-mvs&view=mesh`, or use the combined dense route without `view=mesh` to keep the photorealistic world panorama in front. The dense surface is vertex-colorized, relative-scale only, and review-required; it is not a surveyed historical model. The repository records the v2 runtime dependencies with `npm install @mkkellogg/gaussian-splats-3d three`. The deployed static page imports the browser builds from jsDelivr so no bundler is required; the package install is also available to a future React/Vite build. The viewer accepts a reviewed binary_little_endian 3DGS PLY or `.splat`; the checked-in ASCII PLY remains an evidence fallback and is never mislabeled as a Gaussian model. When a reviewed Gaussian asset is present, the viewer is configured with `webXRMode: GaussianSplats3D.WebXRMode.VR` and requests a local-floor session. The page includes a photorealistic interpretive render generated from multiple archival reference views. It is a derived presentation layer with a visible disclaimer: it is not an original 1893 photograph, exact pixel recovery, or surveyed historical record. Future scenes should use the same multi-view render pattern while keeping cited evidence primary. The WebXR preview now opens in environment-first mode: the equirectangular-style photorealistic environment is the clean default view, while the procedural building, terrain, canal, bridge, trees, and evidence cloud are explicitly alignment guides. Use **Show alignment guides** when reviewing spatial fit. This does not replace the reviewed binary 3DGS handoff; add a `.splat` or binary_little_endian 3DGS PLY through the model picker when the reconstruction is ready. Hotspot content and approximate model-space positions are mirrored in the shared `/data/hotspots.json` contract (with the scene-local copy retained for backward compatibility). Each hotspot carries a citation, image, confidence, and disclosure that its position is not a completed survey alignment. ## Local Palimpsest map-to-scene fit Use the [Library of Congress 1892 exposition map](https://www.loc.gov/resource/g4104c.ct002834/) as a cited source and the [Chicago Park District Statue of the Republic location](https://www.chicagoparkdistrict.com/parks-facilities/statue-republic) as the present-day site anchor. The [City of Chicago CPD_Park_Art GIS record](https://data.cityofchicago.org/resource/pxyq-qhyd.json?objectid=73) supplies the point used here (`41.77959801, -87.5798960788`; object 73, “The Republic (Golden Lady)”). The Park District identifies the memorial as installed on the former Administration Building site. The plotted pin is therefore a site anchor only, not the building's historical centroid or a surveyed footprint. The GIS record publishes no horizontal accuracy; the 180 m radius is a provisional display/search radius, not a measured error bound. On the Qurmmius Palimpsest page, upload a cited historic map, click at least three identifiable landmarks, enter their WGS84 coordinates, then pair each landmark with the same point on the interactive WCE scene plan. The plan uses the same viewer-local X/Z proxy frame as the WebXR scene (building centered at `0,0`, +X right, +Z down); its building, bridge, and canal are schematic interpretive proxies, not surveyed footprint geometry or preselected evidence. Precise map-to-geometry alignment requires reviewed shared landmarks and a metric reconstruction; the current site point alone cannot georeference the viewer model. The affine fit rejects collinear ties, reports its residual, and limits its map extent to the viewer ground area. ### AutoFit manifest workflow Palimpsest can now import `qurmmius.palimpsest.autofit-controls.v1` JSON for a specific, dimension-matched map image. Use **Download control template** after selecting the map, enter at least three non-collinear map-pixel/WGS84 controls with an HTTPS coordinate-source citation for each, and add an independently sourced held-out check. Importing the manifest automatically validates it, solves the geographic fit, calculates residuals, and stages the review-required local preview. Scene X/Z ties are accepted only with a cited `scene_calibration_source`; viewer-plan clicks are still visual proxy placement, not a metric survey. The tool does not perform computer-vision landmark recognition or infer coordinates from an unreferenced image. The current WCE inputs do not yet satisfy AutoFit: the verified Park District / City point is only one site anchor, the LOC map has not been digitized into georeferenced controls, and the scene frame is unsurveyed. AutoFit therefore does not fabricate a fitted WCE overlay. Even after a fit, low residuals do not certify accuracy; independent review and survey calibration remain required. ### Speculative geometry registry (isolated from AutoFit) Palimpsest can record a source-backed `TEXTUAL` or `TOPOGRAPHIC` hypothesis as a geodesic point projected from the WCE site's one present-day City GIS anchor. This is a local, operator-entered hypothesis registry—not a map alignment engine. Entries preserve the citation, note, entered true-north bearing, distance in meters, and any stated input uncertainties. Bearing and historical unit conversions must already be supported by cited evidence; the tool does not parse archival prose or ingest elevation/topography data. The WCE anchor is the present-day Statue of the Republic memorial point on the former Administration Building site. Its horizontal accuracy is unpublished, and it is not a surveyed historic footprint centroid. Every projected point is marked `absolute_accuracy_verified: false`, `validation_state: pending_external_review`, and `terrain_ingested: false`. Scene coordinates are null; hypotheses are excluded from AutoFit and EraWeaver. The export is an isolated JSON manifest only—no GeoJSON, fitted overlay, certification, or claim of solved scale/orientation is produced. Records stay in this browser's local storage unless explicitly exported, so export the manifest for backup. When a scene fit is staged, the cited source image is kept in this browser's IndexedDB, with only transform/citation metadata in localStorage. Open the WCE scene in the same browser profile and use **Show fitted Palimpsest map** to toggle the source map as a planar ground texture. **Hide fitted Palimpsest map** removes it from view. Clearing the local layer also removes its locally stored image. No image is uploaded or included in GeoJSON. This feature overlays a 2D map; it does not alter the reconstruction, ground shape, navigation/collision, camera solution, scale, or panorama. Scene units are not meters. The geographic and scene residuals only show how well the operator-entered points fit the chosen transforms, not whether the landmarks are historically correct. Verify the original source and rights, all point correspondences, local frame/orientation, uncertainty, and cultural context with a qualified reviewer before publication or external use. A legacy geographic-only handoff will not automatically display a map until it is paired to at least three non-collinear scene points. ## Source and rights Every record points to its Library of Congress catalog page. LOC records differ in their rights advisories; confirm the item-level advisory before redistributing any image. Generated sky pixels are never presented as recovered historical evidence.