|TSM/TDM Science Team Meeting 2016|
|Science Team Meetings|
|How to Submit a Proposal|
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|TanDEM-X Science Service System|
|Title||Forest clear cut mapping|
|Investigator||Rauste, Yrjö - VTT Technical Research Centre of Finland, VTT Information Technology|
|Summary||Objective and method
Clear-cut monitoring is of special interest to forest authorities, because it is a statutory task of regional Forestry Centres. Compared to optical data, an all-weather radar sensor has the advantage that a once per year coverage (even at a specific time interval within a year) can be guaranteed. High spatial resolution is also an advantage in clear-cut mapping because the trends in current forest management practices (to safeguard aesthetic values of forest land and to closer emulate the natural renewal of forest canopy) are towards smaller and narrower clear-cut areas.
Active and passive calibration devices will be deployed in the forestry study site during image acquisitions. This calibration stage is aimed to ensure the reliability of the derived information. The employment of multi-temporal SAR data requires that the absolute radiometric calibration of images is adequate. This can be investigated and verified by Cal/Val activities. The calibration experiments in Finland can be also compared with experiments carried out elsewhere (especially if calibration sites fall in the same orbit) in order to assess the short and long term stability of the instrument.
Data pre-processing will include geometric and radiometric correction to enable efficient analysis within image processing and GIS tools. Change detection methods will be used to identify clear-cut and classification algorithms will be experimented to obtain forest type information. Speckle filtering issues will be addressed as well. The temporal behaviour of boreal forest types will be analysed in view of applying parallelepiped classifiers with X-band SAR data. Analysis results and related prototype products (clear-cut and forest type maps) will be evaluated in close collaboration with the user.
Data acquisition plan includes different imaging modes of the TS-X instruments. The potential of wide swath ScanSAR X-band data and Spotlight HH image mode will be evaluated with two acquisitions (at the beginning and at the end of the logging season). If available, the full polarimetric mode will be experimented as well. Finally, the core of the analysis will be performed on a time-series of dual polarisation HH/HV Stripmap images, acquired with a frequency of 1 scene per 33 days (3 orbit repeating cycles). An extensive use of ground data is foreseen, including forestry (stand-wise forestry inventory, clear cutting plans and reports) and meteorological data (temperature, soil moisture, snow thickness and moisture).Deliverables
A project proposal is under preparation to apply for funding from TEKES (National Research Agency of Finland) on a 3-year basis. This project is based on the development of new applications for the new space borne SAR sensors that will be available within the next 18 months: ALOS PalSAR, Radarsat-2 and TS-X. The main targeted applications of the project framework are: forest clear cuts mapping and monitoring, nuclear repository site monitoring, sea ice mapping, natural hazards (i.e. landslides, land subsidence, floods), border security.
As a leading research institute in the fields of geographic information and space borne systems exploitation, VTT will also invest a particular effort on this project. When the 3-year baseline project is completed, each application will be evaluated in close collaboration with the users to determine whether or not more research efforts are needed or if the application has suitable commercial perspectives.
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