Get reliable rangeland science

Agreement Between Measurements of Shrub Cover Using Ground-Based Methods and Very Large Scale Aerial Imagery
Author
Moffet, Corey A.
Publisher
Society for Range Management
Publication Year
2009-05-01
Body

Very large scale aerial (VLSA) photography is a remote sensing method, which is collected and analyzed more efficiently than ground-based measurement methods, but agreement with ground-based measurements needs to be quantified. In this study, agreement between ground- and image-measured cover and precision, and accuracy of image locations and scale, were assessed. True image locations were determined by georeferencing images and conducting a ground search. Accuracy and precision of planned, aircraft, and georeferenced locations were evaluated by comparison with true image locations. Shrub cover was measured at true image locations using ground-based line-intercept and on the image using point-intercept. Sagebrush (Artemisia spp. L.), antelope bitterbrush (Purshia tridentata [Pursh] DC.), and spineless horsebrush (Tetradymia canescens DC.) were distinguished in the imagery. Agreement between ground- and image-based measurements was quantified using limit-of- agreement analysis. True ground locations of the VLSA images were within a 41-m radius of the aircraft location at the time of image acquisition, with 95% confidence. Using a panchromatic image from the QuickBird satellite (0.6-m pixel resolution) as a base map, 90% of true ground locations were within a 5-m radius of the location estimated from georeferencing the VLSA image to the base map. VLSA image-measured cover was, in general, unbiased with mean absolute differences between VLSA- and ground-based methods less than 1.3%. The degree of agreement and absence of bias between VLSA image-measured and ground-measured cover is sufficient to recommend using VLSA imagery to measure shrub cover.  The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact lbry-journals@email.arizona.edu for further information. Migrated from OJS platform August 2020

Language
en
Resource Type
Text
Document Type
Journal Issue/Article
Digital Object Identifier (DOI)
10.2111/08-244R.1
Additional Information
Moffet, C. A. (2009). Agreement between measurements of shrub cover using ground-based methods and very large scale aerial imagery. Rangeland Ecology & Management, 62(3), 268-277.
ISSN
0022-409X
OAI Identifier
oai:repository.arizona.edu:10150/643027
Journal Volume
62
Journal Number
3
Journal Pages
268-277
Collection
Rangeland Ecology & Management (REM)
Journal Name
Rangeland Ecology & Management
Keywords
antelope bitterbrush
georeferencing
limit-of-agreement analysis
mountain big sagebrush
spineless horsebrush