Trees in urban areas, most notably at parks, schools, and recreation sites, are recognized as an index of comfort of a city environment. It is considered that the influence factors include not only the distribution of trees but also "the canopy volume" of trees (i.e., the volume underneath a tree's canopy). This paper presents an approach to the estimation of tree canopy volume using airborne Light Detection and Ranging (LiDAR) data and multi-spectral imagery. By combining the estimated canopy volume with measured tree height data, the effects of canopy volume on three dimensional urban environments were analyzed. For this paper, the study site was the National Cheng Kung University (NCKU) campus. LiDAR data and Remote Sensing Imagery were used to estimate the tree canopy volume. Using the computed canopy volumes and the tree height, the relationship between these two variables in urban settings was studied. The results of our work show that the accuracy of tree canopy estimation is greatly influenced by the tree height, a variable that is dependent upon the specie and foliage density of a tree. In general, trees with greater levels of tree top irradiation provide higher accuracies.