title: Point sampling digital imagery with 'SamplePoint'.
abstract: Measuring percent occurrence of objects from digital images can save time and expense relative to conventional field measurements. However, the accuracy of image analysis had, until now, not reached the level of the best conventional field measurements. Additionally, most image-analysis software programs require advanced user training to successfully analyze images. Here we present a new software program, 'SamplePoint,' that provides the user a single-pixel sample point and the ability to view and identify the pixel context. We found SamplePoint to allow accuracy comparable with the most accurate field-methods for ground-cover measurements. Expert use of the program requires minimal training and its ease of use allows rapid measurements from image data. We recommend SamplePoint for calibrating the threshold-detection level of image-analysis software or for making direct measurements of percent occurrence from digital images.
authors.affiliation: Rangeland Scientist and Remote Sensing Technician, USDA Agricultural Research Service, High Plains Grasslands Research Station, 8408 Hildreth Rd, Cheyenne, WY 82009, USA. Terry.Booth@ars.usda.gov
authors.forename: D Terrance
authors.initials: DT
authors.lastname: Booth
authors.forename: Samuel E
authors.initials: SE
authors.lastname: Cox
authors.forename: Robert D
authors.initials: RD
authors.lastname: Berryman
mesh_terms: D003116:Color; D004784:Environmental Monitoring / Q000379:methods; D007091:Image Processing, Computer-Assisted; D012984:Software