CD/DVD Products

      1.    What is on the Cropland CD/DVD?
      2.    Do I need any special type of GIS or Image Processor to view the CD/DVD?
      3.    How many years of imagery are available on the CD/DVD?
      4.    What format are the images published in?
      5.    What projections are used?
      6.    What other spatial data layers are available on each CD/DVD?
      7.    What other information or metadata is available on the CD/DVD?
      8.    Can I re-distribute the images, vector data or ArcReader software?
      9.    Who created the Cropland datasets?
      10.  To whom do I address concerns about the datasets?
      11.  Why was the dataset created?
      12.  How statistically accurate are the classifications?
      13.  What are the geo-positional errors or spatial accuracies associated with the
            Cropland categorized images?
      14.  What new products can be anticipated in 2007?
      15.  What potential uses do you foresee for the Cropland Data layer?  
      16.  Where can I find metadata about the Cropland Data Layer images?  

Program Methods

      1.   What satellites do you use for your Acreage Estimation Program?
      2.   Do the classifications cover the entire state?
      3.   Why are you not performing this program across the entire country?
      4.   NASS says this is a Cropland data layer product, what about the areas that are not
            agriculturally intensive?
      5.   What observation dates does the SARS typically use for acreage estimation?
      6.   Do the classifications added to county and State level match the official NASS
            estimates?

Program Software

     1.   What software is used to create the classifications?
      2.   What platform does PEDITOR run under?
      3.   Is PEDITOR software currently being maintained?
      4.   What software was/is used to create the mosaics?
      5.   Can I get a copy of PEDITOR/See5?
      6.   Can I get training or support in PEDITOR?
      7.   Why does SARS use PEDITOR rather than commercial software for their image
            processing needs?
      8.   What software is used for processing batch type jobs on XP?
      9.   What other remote sensing/GIS publications/reports has SARS released in the public
            domain?
      10. Why does the mosaic have the appearance of scene or stitch lines running
            throughout the image?
 

CD/DVD Products

What is on the Cropland CD/DVD?

Each CD/DVD contains the rasterized Cropland data layer of a particular state, categorization accuracy statistics by state, ancillary vector Shapefile data layers (e.g., Agricultural Statistics Districts, Area Frame Land Use Stratum, county boundaries, and major roads), a screen show of the project’s methodology, ESRI’s ArcReader freeware software, an image metadata document, and an ArcReader project that bundles up the raster and vector datasets together for display in ArcReader.
 

Do I need any special type of GIS or Image Processor to view the CD/DVD?

No, you can install ArcReader from the Cropland CD/DVD or you can go to the ESRI website and download a copy at http://www.esri.com/arcreader.  ArcReader will allow you to browse both the raster and vector spatial data Cropland datasets.  A premade ArcReader Published Map Documents folder with ArcReader projects can be found in the \PublishedMapDocuments folder.

Note: Users who already have ArcGIS installed on their Desktop systems may consider using the \Mapdocuments forlder to load the premade ArcGIS .mxd project of each state. If preinstalled ArcGIS users try to install ArcReader, they will be required to remove ArcGIS from their desktop, this is not a recommended course of action!

If you already have GIS capability, you should have no trouble importing the datasets.
 

How many years of imagery are available on the CD/DVD?

Each CD/DVD contains one year of categorized imagery.  Space limitations can make it impossible to include any additional years.
 

What format are the images published in?

The images are published in GEOTIFF and Erdas Imagine .IMG format.

What projections are used?

The newest CDL products are projected in Albers Conical Equal Area with a Spheroid of GRS 1980 and a Datum of NAD83. Each state with the exception of Wisconsin is also projected in the UTM projection.  The spheroid is WGS84, datum WGS84, and pixel size is now 56 meters.  The following States are projected into these UTM zones:  ID 11, KS 14, NE 14, ND 14, OK 14, SD 14, AR 15, IA 15, LA 15, MN 15, MO 15, MS 16, IL 16, IN 16, OH 17.  The Towson project states are projected as follows:  UTM 17 - NC, VA, WV; UTM18 CT, DE, MD NJ, NY, PA, RI; UTM19 - RI.  However, Wisconsin, is projected using the Wisconsin Transverse Mercator (WTM) projection.  This WTM projection is based on the 1991 adjustment to NAD83, and is called WTM83/91.
 
Projection parameters and other information about WTM83/91 is posted on the DNR website:
    http://www.dnr.state.wi.us/maps/gis/wtm8391.html

Here is a listing of the WTM83/91 parameters:

Projection:                                     Transverse Mercator
Scale Factor at Central Meridian:        0.9996
Longitude of Central Meridian:            90 Degrees West (-90 Degrees)
Latitude of Origin:                            0 Degrees
False Easting:                                 520,000
False Northing:                                -4,480,000
Unit:                                             Meter
Horizontal Datum:                            NAD83, 1991 Adjustment (aka HPGN or HARN) 

What other spatial data layers are available on each CD/DVD?

The Agricultural Statistics Districts (ASD), County boundaries, major roads, railroads, hydrography, and the Agency’s Area Frame Land Use Stratification of the chosen state could be included in ESRI’s Shapefile format. All shapefiles except the Area Sampling Frame were accessed from the National Atlas website.

An ASD is defined as a contiguous group of counties having relatively similar agricultural characteristics.  The ASD’s used by NASS usually divide each state into as many as nine Agricultural Statistics Districts to make data comparison easier. Each district is more homogeneous with respect to agriculture than the state as a whole. They are usually numbered first from west to east then from north to south. The ASD shapefile of the U.S. is available for download.

An explanation of the NASS Land Use Stratification can be found at http://www.nass.usda.gov/research/AFS.htm
 

What other information or metadata is available on the CD/DVD?

Accuracy statistics such as percent correct and kappa coefficients are presented statewide in .html format, regression analysis by crop type in .html format, the satellite type and dates of observation, and the sampling and associated Area Frame information.  An extensive metadata file is also available, which provides extensive detail about the CDL images.
 

Can I re-distribute the images, vector data or ArcReader software?

Yes, you are under NO copyright restrictions with either the NASS Cropland categorized imagery or ESRI’s ArcReader.  The NASS Cropland categorized imagery is considered public domain and FREE to redistribute.  However, NASS would appreciate acknowledgment or credit for the usage of our categorized imagery.
 

Who created the Cropland datasets?

Traditionally the field preparation and digitizing work were performed in NASS’s Field Offices, and the remote sensing analysis performed by the SARS of NASS.  However, in 1997 the SARS entered into a data sharing partnership with USDA’s Foreign Agricultural Service and USDA’s Farm Services Agency.  The agreement provided access to Landsat 5 coverage in the States selected for the project by the Spatial Analysis Research Section.  The first States covered with the data sharing partnership were Arkansas, North and South Dakota.  Improvements in hardware along with software enhancements made program expansion possible for the 1999 growing season.  So NASS’s Research & Development Division Director solicited additional States to find outside cooperators/partners would support a state analyst and hardware to perform duties associated with the Acreage Estimation Program.  Illinois, and Mississippi were able to obtain partnership agreements with external State/Federal Agencies.  In 1999, our partners were trained in PEDITOR processing, and produced the 1999 classifications, while the SARS mosaiced the categorized scenes together and put together the final CD/DVD package.

For crop year 2000, the states of Iowa and Indiana were added to the Program.  North Dakota was able to obtain a partner for the 2000 crop year.  Indiana was added to the program for crop year 2000 also, but as a regional type center where the ground data collection, and digitization will be performed at the Indiana State Office, and the acreage estimation was performed at the Illinois State Office.

For crop year 2001, the Missouri boot heel area was added to the program.  All boot heel digitizing was performed by the Missouri Ag Statistics Service, and image processing duties were performed by the Arkansas Ag Statistical Service.  Nebraska and Wisconsin were added as pilot States, where all digitizing was performed by the Nebraska and Wisconsin Ag Statistics Service offices respectively, and image processing functions were performed by the SARS group in Fairfax, VA.  Maryland/Delaware were also added as a pilot program where digitizing was done by the Univ. MD Mid-Atlantic RESAC group, and image processing was performed by the SARS group.

For crop year 2002, Nebraska expanded to full state coverage, and Wisconsin expanded to full state coverage in 2003.  The 10 State Mid-Atlantic project is being funded through  with the digitizing and image analysis being performed under contract by SARS, and the Cropland Data Layer will be based on 2002 ground survey data.

For crop year 2004, the IRS ResourceSat 1 AWiFS sensor was used over Nebraska, Indiana and Arkansas to perform acreage analysis. The AR, IN and NE CDL 's will be released with both Landsat TM classifications as well as AWiFS classifications. The AWiFS sensor has 56 meters multispectral resolution, and five day repeat coverage. The best possible scene dates taken during the month of August 2004 were used to create the AWiFS CDL products. The AWiFS scenes were orthorectified to a resampled EarthSat GeoCover base of 56 meters. A Florida CDL for 2004 was released in February of 2007 using Landsat 5/7 imagery. The Florida CDL was the first CDL created exclusively with See5, and it was the first usage of the segmentation based gap filled Landsat-7 SLC-off imagery. It included the first usage of the Farm Service Agency Common Land Unit and the Florida Citrus Grove layer for ground truth training.

The 2002 Mid-Atlantic based Cropland Data Layer product was sponsored in part by a NASA/Raytheon/Synergy Project through Towson University, with the digitizing and image analysis being performed under contract by NASS.  The Cropland Data Layer products were based on the 2002 June Agricultural Survey and the Agriculture Coverage Evaluation Survey (ACES) that coincided with the 2002 Agricultural Census.

The 2005, Idaho Cropland Data Layer was created with a cooperative partnership between a Utah State University Grad Student, the United Potato Growers of Idaho and NASS. This partnership produced both a Landsat TM and ResourceSat-1 AWiFS classification over the Idaho Snake River Plain. The 2005 Midwestern CDL DVD update, contains new AWiFS classifications and a revised Wisconsin TM based classification. The new AWiFS classifications cover Nebraska and North Dakota. The Wisconsin revision was performed under contract for the Wisconsin State, Bureau of Environmental & Occupational Health and Department of Health and Family Services. The Wisconsin CDL is now a complete statewide classification that is nearly cloud free, additional small acreage crops are identified and the non-ag land uses across the state are better defined. The 2005 Mississippi Delta CDL DVD product contains four states: Arkansas, Louisiana, Mississippi and the Missouri (bootheel). This is truely a unique product where the intensely cultivated Delta Region was classified using regression tree classifier See5.0 available from www.rulequest.com over the 2001 NLCD defined mapping Zone 45 http://www.mrlc.gov/ for the States of Arkansas, Louisiana and Missouri. The Zone 45 classification results from See5.0 were overlaid on top of the Arkansas, Louisiana and Missouri bootheel, resulting in an accurate ag classification and an enhanced non-ag land use classification leveraging results from the 2001 NLCD products at www.mrlc.gov. This new prototype product will serve as a basis for future CDL land use classifications. The traditional pixel based PEDITOR classification covers the remaining parts of these states. Additionally, 2005 AWiFS classifications of these four states are provided as well.

The 2006 Midwestern/Pacific Northwest CDL DVD product contains seven States including Illinois, Indiana, Iowa, Nebraska, North Dakota, Washington and Wisconsin. Illinois and Indiana were processed with Peditor. The remaining States were processed using See5 decision tree software. The Mississippi Delta CDL and the remaining Midwestern and Prairie States were processed exclusively with See5 using the FSA Common Land Unit for ground truth.

To whom do I address concerns about the datasets?

Distribution issues can be directed to the NASS Customer Service Hotline at 1-800-727-9540.

Content questions on the CD/DVD can be directed to 703-877-8000 or email HQ_RDD_GIB@nass.usda.gov
 

Why was the dataset created?

The datasets were created as an offshoot from the Acreage Estimation Program.  Historically used for its statistical methodology and ability to produce acreage estimates in table/spreadsheet format.  Functionality was extended into the GIS mapping world.  Program functionality now allows for exporting categorized images to commercial vendor formats for mosaicking purposes.  Once the images were stitched together, the next step was to bundle this data together and distribute it within the Agency and to selected researchers in the GIS community.  It was necessary to bundle ArcReader for potential customers who do not possess a GIS that could display the images.  The output products and Acreage Estimation Program attracted the partnerships previously mentioned.  Now NASS is delivering this product via the web @ the Geospatial Data Gateway.
 

How statistically accurate are the classifications?

The classification’s accuracy metadata is published on the CD/DVD in .html format.  NASS reports the input scenes and sensors used, percent correct and kappa coefficients, statewide regression analysis, the sampling frame scheme, and the original cover type signatures, all of which are displayed in .html format. Look in the /Statinfo directory to find this information.
 

What are the geo-positional errors or spatial accuracies associated with the Cropland categorized images?

The categorized images are co-registered to MDA/EarthSat Inc’s ortho-rectified GeoCover Stock Mosaic images using automated block correlation techniques.  The block correlation were run against band two of each original raw satellite image and band two of the GeoCover Stock Mosaic.  The resulting correlations were applied to each categorized image, and then added to a master image or mosaic using PEDITOR.  The MDA/EarthSat images were chosen as they provide the best available large area ortho-rectified images as a basis to register large volume Landsat images with.  The GeoCover Stock Mosaics are within 50 meters root mean squared error overall.  See MDA/EarthSat’s http://www.mdafederal.com/home website for further details.

The AWiFS images purchased beginning in 2005 were all orthorectified by GeoEye, and there is no longer a need to perform ortho corrections onto the raw or processed imagery. A whitepaper published at the 2005 ASPRS conference discusses the accuracy of the AWiFS images. 

What new products can be anticipated in 2007?

New CDL products for the Midwest and Northern Great Plains States will be released into the public domain using Resourcesat-1 AWiFS imagery purchased from GeoEye. Expect all AWiFS classifications for crop year 2006 because of the ongoing concerns of the Landsat platform. Additionally, many states will be processed with the See5.0 classifier and/or PEDITOR software.

Oklahoma, South Dakota, Minnesota, Ohio, Kansas, and the full State of Missouri will be processed for crop year 2006 and released hopefully in the summer of 2007. For crop year 2007, expect the following CDL products: AR, CA, IA, IL, IN, KS, LA, MI, MO, MN, MS, ND, NE, OH, SD, & WI.

  What potential uses do you foresee for the Cropland Data layer?

There are many possible uses for the Cropland data layer inside and outside the farming community.  It can be leveraged in a GIS to perform spatial queries against other enterprise GIS data layers. The cropland layer could be extracted and used as a mask for other public or private entities so that they could focus solely on their own interests by eliminating all cropland areas, and focus on areas such as; urban sprawl, watershed analysis, de-forestation,.  Other examples range from water quality assessments and monitoring of watersheds, agribusiness facility location, agribusiness transportation routing/forecasting, studying crop rotation patterns and migration trends, crop pesticide applications, wildlife habitat monitoring, and crop stress or blight location.  These are just some of the possibilities that are available for this data set. The following table lists some additional uses:

Ag Market Segmentation	Agribusiness planning	Analyses of Co2 fluxes
Analyzing watersheds, soil utilizations, & crop rotations	Assist with water use estimates	Assisting in education, research & outreach
Background data for research development	Background information for land use categories	Business analysis
Carbon cycle research	Comparison with our Climate Atlas	Crop rotation analysis
Data for students to practice on in Advanced Cartography class	Demographic Research	Determine acres of crop type within conservation projects
Distribution of land among forest, urban, crops & water.	Doing a theoretical radioactive plume impact assessment for crops	Environ lanscape analysis
Epidemiological research	Fertilizer Company looking at where the acres are	Fertilizer usage/potential
For archival purposes	GIS analysis of Mallard nesting sites/targeting restoration activities	GIS Reference layer
Globle irrigated area mapping	Habitat project planning	Incorporate these data sets into other landcover studies
Land cover analysis	Land use and conservation issues along the rural-urban interface	Landcover to calibrate/validate in house classifications
Mapping crop areas, using MODIS images in global scale	Market data analysis for land sales and appraisals	Market research
Modeling of environmental impacts from agriculture	Modelling support	Nutrient load in watershed modeling
Overlay with health statistics to estimate pesticide exposures	Post-stratification of forest inventory estimates	Precision farming, land classification
Research on future crop loss	Scientific research	Soil erosion prediction
Study for transportation project	study hurrican damage	Study of climate effects on vegetation
Teaching	To be used for Eco System modeling	To compare changes in cropping patterns overtime for Nebraska
To understand heterogeneity within AVHRR pixels	To use for analysis of deer habitat	Trend analysis of cropping patterns and verification of other data sources
Undergraduate teaching	Understand crop density distribution for selecting research locations	Use in spatial analysis by GIS consultants to crop protection industry
Use for agro-ecological zones for crop classification algorithm	Use to develop land management/rotation data files	Used for a project involving the tillage adoption by crop for counties
Used for risk assessment for pesticides/gene flow project	Used to constrain an ecosystem process model for estimating crop productivity	Validate landuse forecast model based on prior landuse classification
Will be used by our Water Use Program Manager	Will be used to aid in emergency operations, planning and recovery efforts for the State of Mississippi	Wish to test as input into area crop production estimation & watershed models

 
Where can I find metadata about the Cropland Data Layer images?

The image metadata files are stored in the \statinfo directory and have the following naming conventions cdlmeta_r_st_20xx.htm, where st is the two character state fips code, and the xx is the two digit year.  The metadata is created from software produced by the USGS and can be found at http://geology.usgs.gov/tools/metadata/.

Program Methods
 

What satellites do you use for your Acreage Estimation Program?

The Spatial Analysis Research Section uses the medium resolution type satellites, including; Landsat 4/5/7, IRS 1C, and IRS-P6 Resourcesat 1.  Currently, it is too costly to use higher resolution satellites to perform crop acreage estimation over a large area.
 

Do the classifications cover the entire state?

Western Arkansas and Northern Missouri were not fully covered in the program until crop year 2006.  Cloud coverage, during any given year, may limit the extent of the area coverage also. Beginning in crop year 2006 all states will be full coverage where possible.

Why are you not performing this program across the entire country?

While it would be nice to have complete coverage of all crops in all states during the growing season, it is just not fiscally or humanly possible at this time.  We are looking in the future to possibly expand coverage into other states, but they must first meet certain criteria.  Since the Acreage Estimation Program uses medium resolution Landsat/IRS imagery for analysis, it is necessary to working in States where agricultural production contains large size/acreage fields.  States whose terrain or where planting practices only allow for relatively small size/acreage fields, then medium resolution sensors are not a good match, and the results may be disappointing.  The probability of cloud cover during the growing season is also a consideration when evaluating new states.  It is possible over the next few years, that if this program remains cost effective, and state partnerships are developed, it could expand into twenty states total, as long as those states have rather large field sizes, human resources are available, medium resolution sensors are still available, have low cloud cover probability during the growing season, and continued budgetary support from NASS.

Begining with crop year 2006, the CDL program will cover all of the NASS speculative corn and soybean states, because of the newly developed program efficiencies, the large swath width and rapid repeat times of AWiFS and the availability and coverage of the FSA Common Land Unit Program.
 

NASS says this is a Cropland Data Layer product, what about the areas that are not agriculturally intensive?

NASS collects the remote sensing Acreage Estimation Program’s field level training data during the June Agricultural Survey.  It is a national survey collected randomly on selected areas of land. The selected areas are targeted toward cultivated parts of each state based on its area frame.  Our enumerators are given questionnaires to ask the farmers what, where, when and how much are they planting.  Our surveys focus on cropland, but the enumerators record all land covers within the sampled area of land whether it is cropland or not.  NASS uses broad land use categories to define land that is not under cultivation, including; non-agricultural, pasture/rangeland, waste, woods, and farmstead.  NASS defines these non-agricultural land use types very broadly, which makes it difficult to precisely know what specific type of land use/cover actually is on the ground.  For instance, there is no breakdown as to the type of woods in a given field/pasture, that’s where the power of a GIS could be useful.  If a external forestry GIS layer was overlaid, the land use can be accurately identified, and the specific cover type can be derived from the data layer.  SARS is developing proportional sampling schemes over the non-ag intensive areas, allowing for the sampling of the NLCD over these areas.
 

What observation dates does the SARS typically use for Acreage Estimation?

SARS prefers to use two dates per scene location.  Usually the first scene is selected early in the growing season April – May, and the other for the mid growing season late June through August.  However, it is usually very difficult to obtain two dates of cloud free imagery for one scene during the growing season.  Sometimes SARS substitutes a fall scene instead of a spring scene, but tries to avoid using a spring and fall scene together.  Two observation dates are preferred for crop separability purposes, (i.e., bare soil vs. hay vs. row or small grain crop) where crops may have similar phenological properties, but produce different reflectance values.  Also, two dates help separate the planted cover, woodland, pasture/rangeland out of the crop mix.  However, if only one date of imagery is available, then it is preferable to choose a mid season date late Jun - early Aug before crop senescence.
 

Do the classifications added to county and State level match the official NASS estimates?

The simple answer is no. The reasons are multiple. First, as explained in the Program Methodology section of this CD, NASS adjusts the classified results by using a regression estimator and ground gathered data from farm operators. The farmer reported data is strictly confidential and only available to NASS employees in a secure NASS site location. The regression estimates are only one input to official State and county crop acreage estimates. In addition to regression estimates, NASS staff use the results of farmer reported data from surveys, Farm Service Agency data where available, agri-business data and the Census of Agriculture data every five years (1997, 2002, 2007 etc.). Thus, the official estimate is the single best number that NASS can come up with giving all of the inputs some representation. The one major advantage of the classified data is that it is available at a geographic level well below the county level.

However; it is possible to pixel count and return acreage numbers close to the official estimate but, pixel counting does not account for cloud covered areas as well as the inaccuracies associated with a pixel based classification.
 

Program Software
 

What software is used to create the classifications?

PEDITOR was the image processing package used by the Spatial Analysis Research Section to create classifications, and produce numerical estimates.  It is currently only used to produce acreage estimates, until a new extimator is developed in SAS. Peditor was developed during the early 70’s using Purdue University’s LARSYS system as a basis for further development.  NASS and the University of Illinois Center for Advanced Computing developed a customized program called EDITOR.  It was made portable to other computer platforms by NASS and the name was modified to PEDITOR.  NASS has supported PEDITOR throughout the LACIE and AgRISTARS programs and continues to today, as PEDITOR has been updated and modified to run on the latest desktop platforms utilizing some of the original algorithms from the LARSYS project.  PEDITOR is comprised of a variety of different programming languages, including; Pascal, Fortran, and Delphi , all of which have been integrated into various PEDITOR programs.   Today, PEDITOR contains a combination of procedures characteristic to commercial image processing packages, geographic information systems, and statistical based packages.

Since 2006 the CDL products were created using a commercial software suite including; ArcGIS for ground truth editing, Erdas Imagine for imagery preparation and pre-classification processing, See5 decision tree software for image classification and eventually SAS for the regression estimator.
 

What platform does PEDITOR run under?

PEDITOR runs under the Windows platform, specifically 2000/XP.  PEDITOR has run on a variety of platforms in the past, including ILLIAC 4 supercomputers, CRAY supercomputers, Digital Equipment Corp. DECSYS10 and MicroVax mini-computers, IBM and PDP mainframes, the original MS/DOS, and Windows 3.1.

However, expert system and automated batch procedures for clustering/classification/mosaicking/estimation MUST be run on a Windows 2000 or XP device.  PEDITOR as it is now constituted will only run under the Microsoft Windows operating systems.  Substantial changes would be required to port all of the programs to run under either Linux or Unix.  The requisite changes would vary from program to program, with some relatively minor, while others would be fairly major.
 

Is PEDITOR software currently being maintained?

Yes, NASS is maintaining the PEDITOR code with a systems engineer who is continually updating the functionality and code corrections when necessary.  NASS is maintaining the regression estimator for crop year 2007, and will phase out Peditor entirely in crop year '08. NASS is investigating the integration of commercial software applications including; ArcGIS, Imagine, See5 and SAS to meet the needs of the NASS processing methodology.
 

What software was/is used to create the mosaics?

This is now a three part answer.  For part one, Erdas Imagine was solely used to create the North Dakota 97/98 mosaics.  PEDITOR performed all of image processing tasks, e.g., clustering, classifying, accuracy assessment, and regression estimation first.  Then the images were exported to Imagine, and mosiaced.  North Dakota 97/98 was precision registered with the assistance of Ducks Unlimited, Bismarck ND http://www.ducks.org/.  DU provided the Spatial Analysis Research Section (SARS) the precision registration coefficients to register each categorized image to accuracies within 15 meters.  The problem with the image registration was that the images were purchased and processed as radiometrically and geometrically corrected, but they were not precision corrected.  Each categorized image in the preliminary mosaic may be off by as much as 2-3 pixels in either the X or Y direction or both directions.  So when comparing different years of imagery to the same area, the pixels may or may not have aligned properly.  The other States in the program have not been precision registered using this method.  The method that DU performed was quite manually intensive, and SARS investigated methods to automate this task.

Now for part two of the answer, SARS has used PEDITOR to precision register each CDL image since 1999.  PEDITOR used EarthSat’s Landsat GeoCover ortho-rectified stock mosaics as a basis for precision registration, and then stitching all of the scenes up together.  PEDITOR is capable of stitching the categorized scenes by prioritizing, cutting on scene edges, or within county boundaries.  So if you want to know what observation date/Analysis District that a certain area/county came from you will have to examine the Analysis District map in \CDL\xxyyinfo.bmp, where xx is the state abbreviation, and yy is the two-digit year. PEDITOR was the software of choice to stitch each state together using the GeoCover product as the ortho-base image from 1999 until 2005.

Part three is the newest method change. Beginning with the 2006 crop year, all CDL products were produced with a combination commercial software suite of ArcGIS for ground truth editing, ERDAS Imagine for image preparation and image preprocessing, See5 decision tree software for image classification and PEDITOR was still used for acreage estimation. The new method mosaics the images together before classification, as the images are purchased already ortho-rectified and once the classification is run, no further mosaicing is necessary.

Can I get a copy of PEDITOR/See5?

Send an email request to HQ_RDD_GIB@nass.usda.gov.  The software is in the public domain, and is therefore, free.  However, it is not designed to be a widespread or particularly user friendly package outside of the Cropland Data Layer Project of NASS. See5 is commercial software available from www.rulequest.com.
 

Can I get training or support in PEDITOR?

Generally, NASS goes not provide training for PEDITOR.  It is generally reserved for the cooperators/partners within the Acreage Estimation/Cropland Data Layer Program.

PEDITOR is maintained by the SARS in-house system engineer.  If software corrections or enhancements are reported/requested, they will be evaluated as to their merit for inclusion into the program.  Routine updates to PEDITOR are not provided unless requested. PEDITOR will be phased out in '08.

Why does SARS use PEDITOR rather than commercial software for their image processing needs?

PEDITOR software was developed in the early 1970’s to determine the value of satellites in estimating crop acreage and production.  Around that same time, many commercial GIS/image processing vendors were first getting started.  PEDITOR was developed with the intent of measuring agricultural production and much effort has been contributed to the refinement of the acreage estimator.  PEDITOR possesses many strengths, including; the ability to perform accuracy assessment on a large scale over entire fields rapidly, chaining multiple programs, acreage estimation with the regression estimator RESTP, and cost – FREE. 

At the present time commercial applications are being utilized to process the CDL since '06. The commercial applications are able to meet the statistical demands of NASS' CDL program.
 

What software is used for processing batch type jobs on XP?

PEDITOR utilizes XLNT software developed by Advanced Systems Concepts http://www.advsyscon.com/ for batch job submission on Windows XP and NT workstations.  PEDITOR submits computationally intensive batch jobs through XLNT such as, Clustering, Classification, Multi-temporal Scene Overlays, Image Mosaicing, expert estimator Restp, and Scene Reformats.  XLNT allows for multiple batch jobs to queue up on the Windows XP devices.  XLNT is used because of its capability to incorporate program executions and data in the same file, and also since it has some programming features in its native script language such as testing and jumps. 
 

What other remote sensing/GIS publications/reports has SARS released in the public domain?

Here's a list of SARS Bibliographies, or view the White Papers from the NASS website.
 

Why does the mosaic have the appearance of scene or stitch lines running throughout the image?