Sitka, AK/Buildings Import
Overview
This page tracks and documents the effort to import building footprints for the Sitka, Alaska area and with them information that includes addresses, elevations, building heights, and community OSM data.
Import Data
Data
The 2012 imagery used in creating the building footprints is in the Public Domain and available to the public for download, the Alaska Division of Geological and Geophysical Surveys hosts the data for the City, Sitka_2012.sid. The address points have been extracted from City and Borough of Sitka parcel data found here. [1]
Digital Elevation Models (DEM) have been created for the Sitka area by FEMA for a tsunami inundation study. These DEMs allow for elevation and building-height data to be extracted for each building. The DEMs are in the Public Domain and can be found here. [2]
The new dataset for Sitka buildings to be imported is here. [3]
License
This data is in the public domain.
Process
Housenumbers and street relationship data from the address data were all attached to the building geometry by a spatial join. Polygon centroids were created for each building footprint and then a point sampling tool was used to extract elevation data from the bare earth Digital Terrain Model (DTM) and the highest hits Digital Surface Model (DSM). The difference was calculated to find building heights.
Paul Norman's ogr2osm was used to convert the shapefile data into .osm data. JOSM was used to check this data for conflicts with current OpenStreetMap data. Existing tags were applied to the new data for the entire dataset. The dataset was thoroughly checked with existing OSM data, combined using the Replace Geometry tool from the utilsplugin2 plugin, and duplicate POIs removed.
Contacts
- Joshua Houston: User page City contact page