Monitoring structural organization and biomass of tropical forest from remote sensing observations constitutes a great challenge. For this, texture analysis of very high spatial resolution (VHR) data can significantly contribute to understand the link between image aspect and forest structure. Within this context, our recent works argued that swapping the spatial domain for the frequency domain permits to consistently characterize vegetation and landscape spatial patterns through coarseness/fineness textural indices. In this paper, we synthesize the main results obtained on the characterization of canopy grain using Fourier-based textural ordination (FOTO) of very high resolution images acquired over terra firme rain forest and high biomass mangroves. In addition, we compare texture indices originating from aerial photographs and Ikonos images. Requirements for developing a standardized measurement of forest canopy grain with broad regional validity are finally discussed.