| snippet:
|
Loudoun County has collected aerial imagery for many years. While imagery has been captured in digital format since the mid-2000s, prior years were captured with film cameras. Rolls of film from previous years were available at the County in film canisters, but unavailable for viewing on modern digital GIS systems. The County initiated a project to have these film rolls scanned into a digital format. The film was then processed using modern photogrammetric techniques to produce a digital orthomosaic of the County. Images from 1979, 1986, 1988, 1990-2007 were processed and delivered as tiled uncompressed GeoTIFF and MrSID mosaic formats. 1979, 1986, and 1988 were captured and produced as color (R,G,B) images, while the remainder were captured and produced as panchromatic (B/W) images. The MrSID mosaics use a 50:1 compression ratio. Approximate seamline locations containing the scan name attribute have also been provided. The aerial imagery generally encompasses the full land area of the County of Loudoun, VA. Images were flown in varying temporal and ground conditions and will exhibit some variation in tone, quality, and positional accuracy.
This digital ortho effort was implemented and administered by the Loudoun County Office of Mapping and Geographic Information. The primary goal was to make this historical imagery available in digital format.
Data are stored in the corporate ArcSDE Geodatabase as a raster feature class. SDE geotabase imagery is available in the County's GIS, whereas copies of source files are provided for public distribution.
The coordinate system is Virginia State Plane (North), Zone 4501, datum NAD83 HARN.
|
| summary:
|
Loudoun County has collected aerial imagery for many years. While imagery has been captured in digital format since the mid-2000s, prior years were captured with film cameras. Rolls of film from previous years were available at the County in film canisters, but unavailable for viewing on modern digital GIS systems. The County initiated a project to have these film rolls scanned into a digital format. The film was then processed using modern photogrammetric techniques to produce a digital orthomosaic of the County. Images from 1979, 1986, 1988, 1990-2007 were processed and delivered as tiled uncompressed GeoTIFF and MrSID mosaic formats. 1979, 1986, and 1988 were captured and produced as color (R,G,B) images, while the remainder were captured and produced as panchromatic (B/W) images. The MrSID mosaics use a 50:1 compression ratio. Approximate seamline locations containing the scan name attribute have also been provided. The aerial imagery generally encompasses the full land area of the County of Loudoun, VA. Images were flown in varying temporal and ground conditions and will exhibit some variation in tone, quality, and positional accuracy.
This digital ortho effort was implemented and administered by the Loudoun County Office of Mapping and Geographic Information. The primary goal was to make this historical imagery available in digital format.
Data are stored in the corporate ArcSDE Geodatabase as a raster feature class. SDE geotabase imagery is available in the County's GIS, whereas copies of source files are provided for public distribution.
The coordinate system is Virginia State Plane (North), Zone 4501, datum NAD83 HARN.
|
| accessInformation:
|
|
| thumbnail:
|
|
| maxScale:
|
16753.5002748069 |
| typeKeywords:
|
["Data","Service","Image Service","ArcGIS Server"] |
| description:
|
|
| licenseInfo:
|
|
| catalogPath:
|
|
| title:
|
COLOR_1988 |
| type:
|
Image Service |
| url:
|
https://agsimage-a1.prod.loudoun.local:6443/arcgis/admin |
| tags:
|
["1988","historical","ortho"] |
| culture:
|
en-US |
| name:
|
COLOR_1988 |
| guid:
|
|
| minScale:
|
3.43111685628045E7 |
| spatialReference:
|
NAD_1983_HARN_StatePlane_Virginia_North_FIPS_4501_Feet |