Browsing by Author "Tuominen, Ville"

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  • Improving Individual Tree Detection Using Drone Remote Sensing for Ecosystem Modeling Purposes
    (2022-08-23) Tuominen, Ville
     Perustieteiden korkeakoulu | Master's thesis
    Remote sensing using drones allows to analyze the state of a forest even at the level of individual trees. Data in the resolution of centimeters in which trees can be delineated can be used to design detailed harvest plans in Continuous Cover Forestry as well as to measure tree growth, health and the effect of external factors such as heat waves on the level of individual trees. This thesis develops methods for Individual Tree Detection based on commonly used local maxima filtering algorithm using high resolution Canopy Height Model (CHM) derived from photos taken using a drone. The creation of CHM is presented by using Structure from Motion -technique. With initial estimate from the local maxima filtering, two further methods to remove incorrect tops are presented to improve the detection quality. The methods are based on inspecting the neighborhood of each top as well as comparing data sets collected before and after selection harvesting in the study site. Challenges for the methods caused by the selection harvesting are also examined. Another novelty is the estimation of the distribution of undetected trees using a statistical method. This is needed since the drone-based CHM does not separate smaller trees under the topmost canopy layer. The parameters for the estimation are derived from field measurements, which are also used for validating the remote sensing results. With the presented methods, a better estimation of the distribution of trees in the study site is obtained as almost all incorrectly observed trees are removed while more actual trees are detected. This distribution can be used to estimate the calculated individual crown parameters for those trees that are not detected by remote sensing, and detailed analysis on the forest ecosystem can be performed.
  • Poliittinen julistetaide presidentinvaaleissa 2006
    (2006) Tuominen, Ville
     School of Arts, Design and Architecture | Bachelor's thesis
  • Satunnaismetsän hyödyntäminen junan vikaantumisen arvioinnissa
    (2020-06-08) Tuominen, Ville
     Perustieteiden korkeakoulu | Bachelor's thesis