This page collects answers to questions we have received about gaplightr.
Q: Does gaplightr estimate LAI like GLA does?
No. gaplightr does not currently produce Leaf Area Index (LAI) estimates. LAI is fundamentally a 3D quantity that cannot be reliably resolved from 2D hemispherical imagery alone, because doing so requires independent estimates of foliage clumping and the projected area of all woody material.
Q: How is the Light Penetration Index (LPI) calculated, and does GLA provide it?
LPI is not provided by the original GLA software. gaplightr defines it as percent transmitted global solar radiation expressed as a fraction: divide percent transmitted global by 100. GLA computes percent transmitted direct, diffuse, and global solar radiation, so LPI can be derived from GLA output using the same formula.