Browsing by Subject "satellites"

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  • Poso, Simo; Häme, Tuomas; Paananen, Raito (Suomen metsätieteellinen seura, 1984)
  • Lindfors, Anders; Riihelä, Aku; Aarva, Antti; Latikka, Jenni; Kotro, Janne (Ilmatieteen laitos, 2014)
    Raportteja - Rapporter - Reports 2014:5
  • Varjo, Jari (The Finnish Society of Forest Science and The Finnish Forest Research Institute, 1997)
    A method was developed for relative radiometric calibration of single multitemporal Landsat TM image, several multitemporal images covering each others, and several multitemporal images covering different geographic locations. The radiometricly calibrated difference images were used for detecting rapid changes on forest stands. The nonparametric Kernel method was applied for change detection. The accuracy of the change detection was estimated by inspecting the image analysis results in field. The change classification was applied for controlling the quality of the continuously updated forest stand information. The aim was to ensure that all the manmade changes and any forest damages were correctly updated including the attribute and stand delineation information. The image analysis results were compared with the registered treatments and the stand information base. The stands with discrepancies between these two information sources were recommended to be field inspected.
  • Pitkänen, Timo P.; Sirro, Laura; Häme, Lauri; Häme, Tuomas; Törmä, Markus; Kangas, Annika (ScienceDirect, 2020)
    International Journal of Applied Earth Observation and Geoinformation 86 (2020)
    The majority of the boreal forests in Finland are regularly thinned or clear-cut, and these actions are regulated by the Forest Act. To generate a near-real time tool for monitoring management actions, an automatic change detection modelling chain was developed using Sentinel-2 satellite images. In this paper, we focus mainly on the error evaluation of this automatized workflow to understand and mitigate incorrect change detections. Validation material related to clear-cut, thinned and unchanged areas was collected by visual evaluation of VHR images, which provided a feasible and relatively accurate way of evaluating forest characteristics without a need for prohibitively expensive fieldwork. This validation data was then compared to model predictions classified in similar change categories. The results indicate that clear-cuts can be distinguished very reliably, but thinned stands exhibit more variation. For thinned stands, coverage of broadleaved trees and detections from certain single dates were found to correlate with the success of the modelling results. In our understanding, this relates mainly to image quality regarding haziness and translucent clouds. However, if the growing season is short and cloudiness frequent, there is a clear trade-off between the availability of good-quality images and their preferred annual span. Gaining optimal results therefore depends both on the targeted change types, and the requirements of the mapping frequency.
  • Poso, Simo; Paananen, Raito; Similä, Markku (Suomen metsätieteellinen seura, 1987)
  • Peng, Shikui (Suomen metsätieteellinen seura, 1987)
    A study of a 194.3 ha area of forest land dominated by Norway spruce and Scots pine in central S. Finland. A general procedure is presented and discussed for integrating data from permanent sample plots and from satellite images for continuous forest inventory of large areas and for compartment estimations. Methods for estimation, updating and statistical analysis are examined.