RU 5-1: Sampling by Compact Regions: compact stratification via PAM (partitioning around medoids) clustering on x and y coordinates.
RU 5-1: Sampling by Variance Quad Tree: VQT computed from first principal component of NAIP imagery.
RU 5-1: Sampling by 3ha Basins: based on topographic survey by RTK GPS.
RU 5-1: Sampling by Estimated Landscape Postition: summit (brown), backslope (yellow), swale (green) landscape positions, estimated from mean curvature.
RU 5-1: Sampling by Approximate Annual Solar Radiation Load: quintles of beam radiance [MJ/sq.m], blue (560 - 640), aqua (640 - 660), green (660 - 680), yellow (680 - 700), orange (700 - 760).