Tile Grid and Coordinate System

Click image to view full-size reference image.

File Name: BOS3D Tile Grid
Updated: July 6, 2021
Formats: Autodesk DXF, Trimble Sketchup, ESRI Shapefile, GeoJSON

Tiling Strategy

The tiling scheme for the BPDA's 3D model serves as a framework for sharing a detailed model of metropolitan extent with design tools that are limited in terms of spatial extent and file-size. By dividing the city-wide model components into snap-together modules, the tile grid provides a framework for registering model collections and terrain meshes that can be precisely snapped together and draped with a variety tiled groundplan images.

Metro Boston 3D Coordinate System

Surveyors and engineers in Massachusetts prepare their official drawings using the Massachusetts State Plane Coordinate System with coordinates expressed in Feet. The origin of the State Plane grid lies outside the state, which makes coordinate references much larger numbers than most most 3D modeling tools can deal with gracefully. The creators of AutoCAD, 3DsMax, Rhino, SketchUp and Blender all recommend moving geospatially referenced geometry closer to the origin to avoid problems of precision when creating, transforming or rendering.

To facilitate on-going exchange of 3D models, the BPDA has chosen a default offset that places the origin to the South-West of Boston and neighboring cities. We expect modelers to use project-specific coordinate origins. Preserving the Metro3D insertion point and a tile boundary with models will make it easy to incorporate updates and exchange models with other Metro 3D Boston users whith perfect geo-registration.

Projected Coordinate System: State Plane Massachusetts Mainland (Feet), North American Datum of 1983.
Vertical Coordinate System for 3D data: North American Vertical Datum, 1988 (NAVD 88) Feet (Height)
Origin / Offset / Insertion Point
The origin of the Metro 3D Boston coordinate system serves as the insertion point for models.

To align Metro 3D Boston grid with True North: Rotate 0.34 Degrees clockwise.

To georeference SketchUp tiles for interoperability with SketchUp's geolcoation tools, see the Notes at the bottom of the SketchUp Models page.

Tips for Geo-Location and Integrating Updates

Maintain geolocation in your models to easily integrate updates from other Metro Boston 3D collaborators.

Download City-Wide Tile Grid Resources

Data Dictionary for Tile Grid Attribute Table

This attribute table is a reference for tile identifiers and tile-center coordinates.

Since the tiles are 5000 feet and square with the State Plane grid, eht state-plane coordinates fom the corners can be calculated by adding or subtracting 2500 feet frm the center coordinate.

Field Name Type Description

Town_Code

Text

A three letter abbreviation of the town name.

Tile_Label

Text

a hyphenated label consisting of the letter designating the tile column and the number reflecting the tile row.

Tile_ID

Text

A concatenation of the Town_Code, underscore, and the Tile_Label string. This identifier is used for naming tiled models and folders elminates tile name conflicts for modeling projects that span multiple towns.

Center_Lat

Text

The latitude of the center of the tile. Assuming the WGS84 earth model.

Center_Lon

Text

The longitude of the center of the tile. Assuming the WGS84 earth model.

BosShift_X

Text

The X coordinate of the tile center. Metro Boston 3D coordinate system

BosShift_Y

Text

The Y coordinate of the tile center. Metro Boston 3D coordinate system

MASP_X

Text

The X coordinate of the tile center. Massachusetts State Plane (Mainland, Feet) coordinate system

MASP_Y

Text

The Y coordinate of the tile center. Massachusetts State Plane (Mainland, Feet) coordinate system