scholarly journals Model-based inference for biomass estimation in a LiDAR sample survey in Hedmark County, NorwayThis article is one of a selection of papers from Extending Forest Inventory and Monitoring over Space and Time.

2011 ◽  
Vol 41 (1) ◽  
pp. 96-107 ◽  
Author(s):  
Göran Ståhl ◽  
Sören Holm ◽  
Timothy G. Gregoire ◽  
Terje Gobakken ◽  
Erik Næsset ◽  
...  
Keyword(s):  
Regression Models ◽  
Laser Scanning ◽  
Model Error ◽  
Airborne Laser Scanning ◽  
Total Variance ◽  
Sample Survey ◽  
Biomass Estimation ◽  
Model Errors ◽  
Model Based ◽  
Airborne Laser

In forest inventories, regression models are often applied to predict quantities such as biomass at the level of sampling units. In this paper, we propose a model-based inference framework for combining sampling and model errors in the variance estimation. It was applied to airborne laser (LiDAR) data sets from Hedmark County, Norway, where the model error proportion of the total variance was found to be large for both scanning (airborne laser scanning) and profiling LiDAR when biomass was estimated. With profiling LiDAR, the model error variance component for the entire county was as large as 71% whereas for airborne laser scanning, it was 43% of the total variance. Partly, this reflects the better accuracy of the pixel-based regression models estimated from scanner data as compared with the models estimated from profiler data. The framework proposed in our study can be applied in all types of sample surveys where model-based predictions are made at the level of individual sampling units. Especially, it should be useful in cases where model-assisted inference cannot be applied due to the lack of a probability sample from the target population or due to problems of correctly matching observations of auxiliary and target variables.

scholarly journals Mapping forest age using National Forest Inventory, airborne laser scanning, and Sentinel-2 data

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Johannes Schumacher ◽  
Marius Hauglin ◽  
Rasmus Astrup ◽  
Johannes Breidenbach
Keyword(s):  
Forest Inventory ◽  
Regression Models ◽  
Laser Scanning ◽  
Site Index ◽  
National Forest Inventory ◽  
Airborne Laser Scanning ◽  
National Forest ◽  
Practical Applications ◽  
Airborne Laser ◽  
Sentinel 2

Abstract Background The age of forest stands is critical information for forest management and conservation, for example for growth modelling, timing of management activities and harvesting, or decisions about protection areas. However, area-wide information about forest stand age often does not exist. In this study, we developed regression models for large-scale area-wide prediction of age in Norwegian forests. For model development we used more than 4800 plots of the Norwegian National Forest Inventory (NFI) distributed over Norway between latitudes 58° and 65° N in an 18.2 Mha study area. Predictor variables were based on airborne laser scanning (ALS), Sentinel-2, and existing public map data. We performed model validation on an independent data set consisting of 63 spruce stands with known age. Results The best modelling strategy was to fit independent linear regression models to each observed site index (SI) level and using a SI prediction map in the application of the models. The most important predictor variable was an upper percentile of the ALS heights, and root mean squared errors (RMSEs) ranged between 3 and 31 years (6% to 26%) for SI-specific models, and 21 years (25%) on average. Mean deviance (MD) ranged between − 1 and 3 years. The models improved with increasing SI and the RMSEs were largest for low SI stands older than 100 years. Using a mapped SI, which is required for practical applications, RMSE and MD on plot level ranged from 19 to 56 years (29% to 53%), and 5 to 37 years (5% to 31%), respectively. For the validation stands, the RMSE and MD were 12 (22%) and 2 years (3%), respectively. Conclusions Tree height estimated from airborne laser scanning and predicted site index were the most important variables in the models describing age. Overall, we obtained good results, especially for stands with high SI. The models could be considered for practical applications, although we see considerable potential for improvements if better SI maps were available.

scholarly journals New Heights of the Highest Peaks of Polish Mountain Ranges

2020 ◽  
Vol 12 (9) ◽  
pp. 1446 ◽  
Author(s):  
Krystian Kozioł ◽  
Kamil Maciuk
Keyword(s):  
Laser Scanning ◽  
Airborne Laser Scanning ◽  
Independent State ◽  
Mountain Ranges ◽  
Gnss Receiver ◽  
Model Based ◽  
Airborne Laser ◽  
Almost All

The idea to verify the height of the highest peaks (summits) in the Crown of Polish Mountains arose after analyzing sources regarding the date and method of measuring the height of these mountain peaks. Our investigations revealed that this type of material is not usually available, and the first mention of height values is most often noted in the inter-war period, and occasionally before WWI (when Poland did not exist as an independent state); most of these values are still in use to this day. The problem of accurate measurement of the height of mountain peaks concerns not only the peaks analyzed by the authors, but also almost all mountain peaks worldwide. Therefore, as part of this work, several trips were organized to the highest peaks of several dozen mountain ranges in the territory of Poland. Measurement was made using a precise geodetic GNSS receiver an accuracy of within 10 cm and a DTM model based on ALS (airborne laser scanning). The results showed that commonly published heights can differ by up to several meters from the actual ones. The most important element of this work consists of the establishment of new measurements of the heights of the highest peaks of all mountain ranges in Poland, which may result in an alteration of the officially recorded heights based on this article. Apart from verification of these heights, this work also aimed to address the issue of the heights of all characteristic objects whose heights must be verified by using modern satellite techniques.

scholarly journals Nově objevené hradiště Čerťák u obce Sovolusky v kontextu halštatského osídlení regionu

2021 ◽  
Vol 6 (1-2) ◽  
pp. 159-176
Author(s):  
Filip Prekop ◽  
Petr Krištuf
Keyword(s):  
Laser Scanning ◽  
Digital Terrain Model ◽  
Field Research ◽  
Airborne Laser Scanning ◽  
Terrain Model ◽  
Model Based ◽  
Digital Terrain ◽  
Airborne Laser ◽  
Scanning Lidar ◽  
Hallstatt Period

This paper presents a new hillfort site which is situated on top of „Čerťák“ Hill (651 m n. m.), Sovolusky municipality, Karlovy Vary district. It has been identified with the help of a digital terrain model based on Airborne Laser Scanning (LiDAR). Two separate lines of stone ramparts have been confirmed on top of the Čerťák Hill, formed by a significant right bank meander in the upper course of the river Střela. The inner area reaches 1.4 ha and the external enclosed area spreads to 2.3 ha. Subsequent field research yielded a collection of more than 500 pottery fragments from the Late Hallstatt period. The dispersion of finds shows relatively intensive settlement. The paper also discusses other sites in the surrounding region which date to the same period. The Hallstatt settlement seems to have been a structurally connected complex in the presented area.

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