Xiaowei Yu

... development of scanning systems and improvements in the accuracy of direct georeferencing, ALS became ... for statistical change detection by re-flying them with roughly same parameters after 10 ... With human assistance the accuracy is enough even for more detailed mapping. ...

... DOI: 10.1080/02827580410019436 Petri Rönnholm a , Juha Hyyppä b ... View all references, 20043. Haggrén H Hyyppä H Jokinen O Kukko A Nuikka M Pitkänen T Pöntinen P Rönnholm P 2004 Photogrammetric application of spherical imaging, Panoramic Photogrammetry ...

Abstract Airborne laser scanning (ALS) has been used in recent years to acquire accurate remote-sensing material for carrying out practical forest inventories. Still, much of the information needed in forest management planning must be collected in the field. For ...

ABSTRACT Accurate forest biomass mapping methods would provide the means for e.g. detecting bioenergy potential, biofuel and forest-bound carbon. The demand for practical biomass mapping methods at all forest levels is growing worldwide, and viable options are being developed. Airborne laser scanning (ALS) is a promising forest biomass mapping technique, due to its capability of measuring the three-dimensional forest vegetation structure. The objective of the study was to develop new methods for tree-level biomass estimation using metrics derived from ALS point clouds and to compare the results with field references collected using destructive sampling and with existing biomass models. The study area was located in Evo, southern Finland. ALS data was collected in 2009 with pulse density equalling approximately 10 pulses/m2. Linear models were developed for the following tree biomass components: total, stem wood, living branch and total canopy biomass. ALS-derived geometric and statistical point metrics were used as explanatory variables when creating the models. The total and stem biomass root mean square error per cents equalled 26.3% and 28.4% for Scots pine (Pinus sylvestris L.), and 36.8% and 27.6% for Norway spruce (Picea abies (L.) H. Karst.), respectively. The results showed that higher estimation accuracy for all biomass components can be achieved with models created in this study compared to existing allometric biomass models when ALS-derived height and diameter were used as input parameters. Best results were achieved when adding field-measured diameter and height as inputs in the existing biomass models. The only exceptions to this were the canopy and living branch biomass estimations for spruce. The achieved results are encouraging for the use of ALS-derived metrics in biomass mapping and for further development of the models.

ABSTRACT Recent research results have shown that the performance of digital surface model extraction using novel high-quality photogrammetric images and image matching is a highly competitive alternative to laser scanning. In this article, we proceed to compare the performance of these two methods in the estimation of plot-level forest variables. Dense point clouds extracted from aerial frame images were used to estimate the plot-level forest variables needed in a forest inventory covering 89 plots. We analyzed images with 60% and 80% forward overlaps and used test plots with off-nadir angles of between 0° and 20°. When compared to reference ground measurements, the airborne laser scanning (ALS) data proved to be the most accurate: it yielded root mean square error (RMSE) values of 6.55% for mean height, 11.42% for mean diameter, and 20.72% for volume. When we applied a forward overlap of 80%, the corresponding results from aerial images were 6.77% for mean height, 12.00% for mean diameter, and 22.62% for volume. A forward overlap of 60% resulted in slightly deteriorated RMSE values of 7.55% for mean height, 12.20% for mean diameter, and 22.77% for volume. According to our results, the use of higher forward overlap produced only slightly better results in the estimation of these forest variables. Additionally, we found that the estimation accuracy was not significantly impacted by the increase in the off-nadir angle. Our results confirmed that digital aerial photographs were about as accurate as ALS in forest resources estimation as long as a terrain model was available.

This paper depicts an approach for predicting individual tree attributes, ie, tree height, diameter at breast height (DBH) and stem volume, based on both physical and statistical features derived from airborne laser-scanning data utilizing a new detection method for ...

This study used high‐density multitemporal laser scanner datasets acquired at different dates between 1998 and 2003 to estimate the tree mean height and volume growth at plot level in a boreal forest. Thirty‐three sample plots were established in a mixed, multiple‐storey forest in Kalkkinen, 130 km north of Helsinki, Finland. Plotwise attributes, such as mean height, basal area and volume, were

... 6. Andersen, H. -E., Reutebuch, S. and Schreuder, G. (2002) Bayesian object recognition for the analysis of complex forest scenes in airborne laser scanner data. ... 14. Brandtberg, T. (1999) Automatic individual tree-based analysis of high spatial resolution remotely sensed data. ...

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ABSTRACT Countrywide collection of laser scanning, mainly due to DTM derivation, is becoming increasingly attractive. Since Finland is a large country, optimization of scanning parameters is important from the economical point of view. High altitude measurements ...

... Table 2. Percentages of trees found for dominant and other trees and bias of height estimates of found trees. ... The bias of height estimates of found trees in Table 2 is the average difference of the height estimates from the CHM and the field measured heights. ...

This paper demonstrates the applicability of small footprint, high sampling density airborne laser scanners for boreal forest change detection, ie the estimation of forest growth and monitoring of harvested trees. Two laser acquisitions were carried out on a test site using ...

ABSTRACT The objective of this study was to determine the suitability of airborne laser-scanning (ALS) and existing stand register data in the estimation of forest site types via dominant height and stand age. Dominant height was estimated with the nonparametric k-...

ABSTRACT The two main approaches to derive forest information from small-footprint laser scanner data are the statistical area-based approach (ABA) and individual tree detection (ITD). In the present study we tested the accuracies of two ABA estimation methods, ...