Terrain Analysis in Google Earth Engine: A Method Adapted for High-Performance Global-Scale Analysis

Autor(es)

Safanelli, Jose Lucas ^[1] ; Poppiel, Raul Roberto ^[1] ; Chimelo Ruiz, Luis Fernando ^[1] ; Bonfatti, Benito Roberto ^[2] ; de Oliveira Mello, Fellipe Alcantara ^[1] ; Rizzo, Rodnei ^[1] ; Dematte, Jose A. M. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Luiz de Queiroz Coll Agr, Dept Soil Sci, Padua Dias Av 11, Postal Box 09, BR-13416900 Sao Paulo - Brazil

^[2] Univ Estado Minas Gerais, 700 Colorado St, BR-37902092 Passos, MG - Brazil

• Tipo de documento: Artigo Científico
• Fonte: ISPRS INTERNATIONAL JOURNAL OF GEO-INFORMATION; v. 9, n. 6 JUN 2020.
• Citações Web of Science: 0

Resumo

Terrain analysis is an important tool for modeling environmental systems. Aiming to use the cloud-based computing capabilities of Google Earth Engine (GEE), we customized an algorithm for calculating terrain attributes, such as slope, aspect, and curvatures, for different resolution and geographical extents. The calculation method is based on geometry and elevation values estimated within a 3 x 3 spheroidal window, and it does not rely on projected elevation data. Thus, partial derivatives of terrain are calculated considering the great circle distances of reference nodes of the topographic surface. The algorithm was developed using the JavaScript programming interface of the online code editor of GEE and can be loaded as a custom package. The algorithm also provides an additional feature for making the visualization of terrain maps with a dynamic legend scale, which is useful for mapping different extents: from local to global. We compared the consistency of the proposed method with an available but limited terrain analysis tool of GEE, which resulted in a correlation of 0.89 and 0.96 for aspect and slope over a near-global scale, respectively. In addition to this, we compared the slope, aspect, horizontal, and vertical curvature of a reference site (Mount Ararat) to their equivalent attributes estimated on the System for Automated Geospatial Analysis (SAGA), which achieved a correlation between 0.96 and 0.98. The visual correspondence of TAGEE and SAGA confirms its potential for terrain analysis. The proposed algorithm can be useful for making terrain analysis scalable and adapted to customized needs, benefiting from the high-performance interface of GEE. (AU)

• Processo FAPESP: 14/22262-0 - Geotecnologias no mapeamento digital pedológico detalhado e biblioteca espectral de solos do Brasil: desenvolvimento e aplicações
• Beneficiário: José Alexandre Melo Demattê
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 16/01597-9 - Pedotransferência por geotecnologias associada à fotopedologia com vistas ao mapeamento pedológico de áreas agrícolas do estado de São Paulo
• Beneficiário: José Lucas Safanelli
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto