%0 Research article
%T Crown envelope shape measurements and models
%A Rautiainen, Miina
%A Mõttus, Matti
%A Stenberg, Pauline
%A Ervasti, Sanna
%D 2008
%J Silva Fennica
%V 42
%N 1
%R doi:10.14214/sf.261
%U https://silvafennica.fi/article/261
%X This paper addresses tree crown envelope shape modeling from the  perspective of optical passive remote sensing. The aims are 1) to review  the specific requirements of crown shape models and ground measurement  techniques in optical remote sensing, and 2) to present preliminary  results from empirical, parametric crown shape and volume modeling of  Scots pine and Norway spruce applicable in Finland. Results indicated  that the basic dimensions (maximum radius, its height and crown length)  of tree crowns were better predicted for pines, but the profile shape of  the upper part of the crowns varied more than in spruce. Pine crowns  were also slightly less concave than spruce crowns. No regularities were  observed concerning the lower part of the crowns. The asymmetry of  crowns increased as a function of tree age for both species, spruce  crowns being more asymmetric than pine crowns. A comparison of measured  crown volume with several simple geometrical crown shape envelopes  showed that using a cone as a crown shape model for Scots pine and  Norway spruce underestimates crown volume most severely. Other crown  envelope shape models (e.g. ellipsoids) rendered crown volumes closer to  the measured volume and did not differ considerably from each other.