A Comparison of Existing Models for DBH Estimation from Large-scale Photos

Abstract

The performance of 12 diameter prediction models suggested in the literature was studied in a controlled operational test. These models were linear and logarithmic transformations of tree height and/or crown area and were analyzed for white spruce, lodgepole pine, and trembling aspen and balsam poplar combined. Overall, all models were statistically significant, with differences due to variations in species and model form. Although simpler models may be adequate depending on operational objectives, two models emerged as deserving further investigation. It was unclear whether both tree height and crown area were needed as predictors of tree dbh for all species. Tree height was more highly correlated with dbh than crown area for all species except lodgepole pine. Measuring both tree height and crown area in comparison with tree height alone, however, increases measurement cost substantially from $10.29 to $17.50 per plot (1987 dollars).

Stand biomass estimation method by canopy coverage for application to remote sensing in an arid area of Western Australia

“…Even with the high-spatial resolution aerial photographs, the direct measurement or the estimation of DBH was revealed to be quite difficult (Hagan and Smith, 1986;Hall et al, 1989). In addition, the correlation between Cpa and DBH of acacia forest in Australia revealed that the R 2 was only 0.42, which was quite weak (Lange and Sparrow, 1992).…”

Modeling Tree Characteristics of Individual Black Pine (Pinus nigra Arn.) Trees for Use in Remote Sensing-Based Inventory

“…Currently, both methods (digital stereo-photogrammetry and ALS) are suitable and enable estimation of H and CD at tree level [6,32]. Research on applicability of high-spatial resolution stereo-images [33][34][35][36] or high-density ALS data [14,37,38] for H estimation showed that H could be estimated with both methods with high accuracy and with no statistically significant difference compared to field measurements. Unlike H, it is more time-consuming and more difficult to accurately estimate crown size (area or diameter) of individual trees from remote sensing data, especially in densely canopied stands where overlapping of the crowns of the adjacent trees is common and complicates crowns measurement of individual trees [4,7,33,38,39].…”

“…Research on applicability of high-spatial resolution stereo-images [33][34][35][36] or high-density ALS data [14,37,38] for H estimation showed that H could be estimated with both methods with high accuracy and with no statistically significant difference compared to field measurements. Unlike H, it is more time-consuming and more difficult to accurately estimate crown size (area or diameter) of individual trees from remote sensing data, especially in densely canopied stands where overlapping of the crowns of the adjacent trees is common and complicates crowns measurement of individual trees [4,7,33,38,39]. Besides stand structure, estimated results of crown dimensions could be influenced by the pulse density of airborne laser scanning or spatial resolution of aerial images, but also by the computer algorithm used for crown delineation in cases when automatic method of delineation was used.…”

Unmanned aerial systems for precision forest inventory purposes: A review and case study

“…To estimate these values, tree crown areas and their corresponding CHM and P95 heights from locally validated samples were fit using local data in the following equation (Hall et al 1989):…”