rasterization, format transformation, pixel value retrieval, statistics calculation, and
change analysis. Cairo API is utilized in the executable programs to render the CDL
image and other map elements in a drawing context, which is exported in PDF
format. These executable programs with multiple parameters are invoked in the
OGC WPS services and geospatial Web services. The WPS services are deployed in
Apache Tomcat, and the geospatial Web services are deployed in the Apache Axis2
runtime environment, which also serves as a stand-alone Web application in Apache
Tomcat.
18.4.1.3 Data Layer
The data layer offers various geospatial and attribute data which are stored in files or
databases that could be accessed directly or indirectly by geospatial data and
processing services (Han et al. 2014a). The data from the data layer are served or
processed by Web services in the service layer, and the retrieved data or the
processed results are sent back to the clients in the application layer. The data
layer includes raster, vector, and tabular data. The raster data includes all historical
CDL layers (from 1997 to current), a Global Land Cover background layer, a crop
mask layer, and crop frequency layers (corn, cotton, wheat, and soybean). The vector
data includes different boundary layers (e.g., states, country, ASDs, and regions) and
auxiliary layers (e.g., roads and waters). The tabular data includes the USDA NASS
county level acreage statistics from the 2007 Census of Agriculture. The annual
CONUS CDL data and available annual State CDL data are mosaicked into a single
raster file, converted to ERDAS Imagine format (.img), and built into tiled pyramid
levels for better display performance. The CDL data, crop mask data, and crop
frequency data are served by WMS and WCS. The Global Land Cover data,
produced by the European Space Agency (ESA), is also served by WMS and
WCS. The boundary files, such as the 2016 TIGER/Line Shapefiles for 48 contiguous states and their counties, the agricultural regions, and ASDs, are served by WFS
to provide the features to define the AOI. Other data, such as the national freeway
system and major regional highways, the rivers and lakes at the national and regional
level, and tabular data of county-level acreage information, are served by WFS to
query feature information.
18.5 Geospatial Data Service Functionalities
for Agriculture
18.5.1 Agricultural Data Management
According to an agriculture data life cycle, data management usually includes data
planning, collection, curation, archiving, cataloging, discovery, access, sharing,
396
L. Hu et al.
change analysis. Cairo API is utilized in the executable programs to render the CDL
image and other map elements in a drawing context, which is exported in PDF
format. These executable programs with multiple parameters are invoked in the
OGC WPS services and geospatial Web services. The WPS services are deployed in
Apache Tomcat, and the geospatial Web services are deployed in the Apache Axis2
runtime environment, which also serves as a stand-alone Web application in Apache
Tomcat.
18.4.1.3 Data Layer
The data layer offers various geospatial and attribute data which are stored in files or
databases that could be accessed directly or indirectly by geospatial data and
processing services (Han et al. 2014a). The data from the data layer are served or
processed by Web services in the service layer, and the retrieved data or the
processed results are sent back to the clients in the application layer. The data
layer includes raster, vector, and tabular data. The raster data includes all historical
CDL layers (from 1997 to current), a Global Land Cover background layer, a crop
mask layer, and crop frequency layers (corn, cotton, wheat, and soybean). The vector
data includes different boundary layers (e.g., states, country, ASDs, and regions) and
auxiliary layers (e.g., roads and waters). The tabular data includes the USDA NASS
county level acreage statistics from the 2007 Census of Agriculture. The annual
CONUS CDL data and available annual State CDL data are mosaicked into a single
raster file, converted to ERDAS Imagine format (.img), and built into tiled pyramid
levels for better display performance. The CDL data, crop mask data, and crop
frequency data are served by WMS and WCS. The Global Land Cover data,
produced by the European Space Agency (ESA), is also served by WMS and
WCS. The boundary files, such as the 2016 TIGER/Line Shapefiles for 48 contiguous states and their counties, the agricultural regions, and ASDs, are served by WFS
to provide the features to define the AOI. Other data, such as the national freeway
system and major regional highways, the rivers and lakes at the national and regional
level, and tabular data of county-level acreage information, are served by WFS to
query feature information.
18.5 Geospatial Data Service Functionalities
for Agriculture
18.5.1 Agricultural Data Management
According to an agriculture data life cycle, data management usually includes data
planning, collection, curation, archiving, cataloging, discovery, access, sharing,
396
L. Hu et al.