|What is a Fiducial site?|
A Fiducial site is a geographic location that is used as a benchmark for the long-term monitoring of processes, both natural and anthropogenic, associated with the causes and effects of global environmental change. The word fiducial carries multiple meanings with regard to the Global Fiducials Program (GFP). Fiducials are marks or points of reference applied to images to present a fixed standard of reference, so in the GFP they refer to the identification of a place on the Earth. The term fiducial may also be interpreted to refer to a long-term trust, where one may be holding something in trust for another. Both references aptly apply, as the GFP maintains a long-term record of data over specific places on the Earth to be available for scientific investigations. Fiducial sites are associated with Earth processes and environmentally sensitive areas that are being monitored so that scientists can better understand and model the dynamic systems and changes that are occurring. The sites are located around the globe and are distributed among environmental topics and processes within five major disciplines: Ocean Processes; Land Use/Land Cover; Atmospheric Processes; Ice and Snow Dynamics; and Geologic Processes.
|How do I find Fiducial sites?|
GFP Sites Map displays Fiducial site locations. The sites are organized by geographic region (Domestic U.S., International, Arctic Sea, and Antarctica). Start by selecting a geographic region using the navigation button on the top of the page. Each geographic location page contains a drop-down list on the top-left that contains all the sites for which data are available in that region. Also each page includes site information.
|How do I find, view & download data?|
The data can be viewed and downloaded from the Image Viewer or Image Gallery. In both, the data are organized by geographic region (Domestic U.S., International, Arctic Sea Ice, Arctic Sea Ice Buoys and Antarctica). Start by selecting a geographic region using the navigation button on the top of the page. Each geographic location page contains a drop-down list on the top-left that contains all the sites available in that region.
Image Viewer allows you to view GFL imagery in the interactive map using the Time Slider. The map for each region is displayed in an appropriate map projection for the region:
Image Gallery displays the thumbnails of all imagery available for each GFP site in chronological order. It provides download links to imagery and metadata files. For Image Gallery instructions, go to Image Gallery Help.
|Where do these data come from?|
This website contains data derived from U.S. National Imagery Systems. These data are available for public use.
|What is the ground sample distance of these data?|
The ground sample distance of these data is one meter. Each pixel is one meter by one meter.
|What is the horizontal positional accuracy of the data?|
Horizontal positional accuracy of approximately 9 meters should be expected, but actual accuracy of individual products is not measured and may vary significantly.
|What is the bit depth of these data?|
The data that can be acquired through this website is 8-bit data.
|Are these data orthorectified?|
All of the data found on this website have been orthorectified.
|Is metadata available for these data?|
Metadata is available along with the data in an FGDC-compliant format. The metadata file has an .XML extension. The metadata file will open in any web browser. Metadata means "data about the data", hence each metadata file carries information about the image file. Location information indicating where the image is located on the earth is recorded in the metadata file.
|What formats are these data available in?|
The data are available as both a GeoTIFF and a GeoPDF.
|What is a GeoTIFF?|
GeoTIFF refers to TIFF files which have geographic (or cartographic) data embedded as tags within the TIFF file. The geographic data can then be used to position the image in the correct location and geometry on the screen of a geographic information display. GeoTIFF is a metadata format, which provides geographic information to associate with the image data. But the TIFF file structure allows both the metadata and the image data to be encoded into the same file. GeoTIFF makes use of a public tag structure which is platform interoperable between all GeoTIFF readers.
Many systems today can read GeoTIFF files into correct geographic position in a variety of Geographic Information Systems (GIS), Image Processors (IP) and Computer Aided Design (CAD) software. You need to check with your system provider to find out if module to read/write GeoTIFF imagery is available for the software version which you use.
|What is a GeoPDF?|
GeoPDF is a published extension (OGC 08-139r1) to the Adobe PDF file format, from TerraGo Technologies. It is used to present GIS and mapping data in a standard Adobe Systems PDF. This extension adds a coordinate transformation matrix and other metadata to allow transformation of PDF coordinates to a projected Cartesian coordinate system. GeoPDFs often include other advanced PDF features such as layers and object data which can add significant GIS functionality to the file, particularly when used with the TerraGo Toolbar®. (Requirements: Windows desktop or web browser (TerraGo Toolbar® does not operate on Mac OS); Adobe Reader version 9.x, X.x or XI or Adobe Acrobat)
|What is the cost to download these data?|
There is no cost to download data from this website.
|Can I order these data on DVD?|
Initially, data from this website will only be available through download. Use the Contact Us button on the top of any page on this website to request consideration for alternative access to the data.
|Can I distribute these data?|
The data available for download through this website are completely unrestricted and may be distributed freely.
|Are vector data available for download over these areas of interest?|
Corresponding vector data are not currently available through this website. However, vector data for these areas may be available through the USGS at:
|Is there any technical support provided for using these data?|
We will answer additional questions not referenced in this FAQ list through the Contact Us button on the top of any page on this website.
|Can I use data derived from U.S. National Imagery Systems in my publication or study?|
All of the data available for download through this website are completely unrestricted and may be distributed freely.