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Proceedings of the 2nd Workshop of the EARSeL SIG on Land Use and Land Cover

VALIDATION METHOD FOR LAND COVER MAPS USING CONFLUENCE POINTS INFORMATION

Koki, I. 1, Kenlo, N. 2, Tsuguki, K. & Yoshiki, Y. 1

1. Center for Global Environmental Research, National Institute for Environmental Studies, 16-2, Onogawa, Tsukuba, Ibaraki 305-8506, Japan; Tel: +81-29-850-2289, Fax: +81- 29-850-2960; e-mail: [email protected] 2. University of Tsukuba, Institute of Agricultural and Forest Engineering, Tsukuba, Japan

We propose a new accuracy assessment method for land cover maps using Degree Confluence Points’ information. “Degree Confluence Project” (hereby DCP) is a voluntary- based project that collects onsite data from all degree confluence points (DCPoints) in the world. DCPoints are located at the intersections of integer level and grid lines. Volunteers with the project visit the DCPoints and collect data in the form of GPS readings, pictures and descriptions of the landscape. This information is freely accessible through the Internet. In this research, reliability and effectiveness of DCPoints information in terms of validation of land cover map was assessed. Focusing on the IPCC LULUCF (Land Use, Land Use Change and Forestry) guidelines, we classified each DCPoint into six classes (Forest, Grassland, Crop, Wetland, Residential, and Other) manually.To assess the reliability, points from duplicate visits’ were checked. In addition, a field survey was conducted. These DCP derived classifications were then compared to classifications derived from Landsat Thematic Mapper images by visual interpretation. We were able to obtain validation information for land cover maps superior to that of visual interpretation. Based on this result, the analysis about the difference of land cover maps was considered.

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