U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 close



Research
                Research Home
                            National Programs
                            Research Projects
                            Scientific Manuscripts
                            International Engagement
                            Scientific Software/Models
                            Databases and Datasets
                            Office of Scientific Quality Review
            Media
                News & Features
                            Multimedia
                            Briefing Room
                            Down on the Farm
                            Press Room
                            Science in Your Shopping Cart
                            Scientific Discoveries
                            Tellus
                            Under the Microscope
            About ARS
                About ARS Home
                            Staff Directory
                            Labs and Research Centers (Map)
                            Headquarter Offices
                            Organizational Chart
                            Employee Services (REE Employees Only)
                            Office of Outreach, Diversity, and Equal Opportunity
            Work With Us
                Work With Us Home
                            ARS Vacancies at USAJOBS
                            Careers at ARS Information
                            Scientific Collaborations
                            Extramural Agreements
                            1890 Faculty Research Sabbatical ProgramSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            Walthall, Charlesitem
                                            Timlin, Dennisitem
                                            Dulaney, Wayneitem
                                            Pachepsky, Yakovitem
                                            Daughtry, Craig
  Submitted to: Intnl Conference On Geospatial Information In Agriculture And Forestry
                                    Publication Type: Abstract Only
                                    Publication Acceptance Date: 11/4/2001
                                    Publication  Date: 11/4/2001
                                    Citation: N/AInterpretive Summary:
                                Technical Abstract: Accurate maps of within-field crop foliage density would greatly assist crop condition monitoring, yield estimation, and assessment of crop response patterns for effective decision making. Vegetation indices (VIs), which are linear combinations of remotely sensed crop spectral reflectances, are positively correlated with foliage density expressed as  leaf area index (LAI). Numerous ground measurements of LAI are required to calibrate an ordinary least squares (OLS) relationship between VIs and LAI. The OLS equation is then applied to the rest of the imagery to map LAI. However, this approach does not fully exploit the inherent spatial information of imagery. Semivariograms describe spatial variance structure and can be derived from surface measurements or imagery. We calculate semivariograms for this analysis from a subset of ground-based LAI measurements, and from a remotely sensed image. These semivariograms are  used to condition stochastic imaging geostatistical simulation to interpolate the LAI for a map. The interpolated LAI maps produced from the stochastic imaging are compared to an LAI map generated using the traditional OLS technique. The remaining LAI measurements are used to assess the accuracy of the approaches for mapping LAI.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov