Gap Light Analyser for 64 bit Windows - David Zelený
Improving gap light index (GLI) to quickly calculate gap coordinates
GLAMA – Gap Light Analysis Mobile App
Beckschäfer P, Seidel D, Kleinn C, Xu J (2013). On the exposure of hemispherical photographs in forests. iForest - Biogeosciences and Forestry 6: 228-237.
Plant Canopy Analyzer
PDF) Terrestrial laser scanners to measure forest canopy gap fraction