Geographic Object-Based Image Analysis (GEOBIA) is an emerging approach in remote sensing image analysis and classification which relies on segments or objects created by a group of pixels on the image. GEOBIA has been utilized for many remote sensing applications with various degree of success. However, from the literature, its application for landform analysis and classification is still rare. This study aims to test GEOBIA interpretation capabilities to identify landform in part of Opak Watershed (Central Java, Indonesia) using Landsat 8 OLI and DEMNAS imagery (30 and 8- meters pixel size, respectively) and evaluate the result. Both image data were fused to create an image with high spectral and spatial resolution and contains elevation data, as an input for the segmentation process. GEOBIA interpretation process was performed gradually; first, initial Multiresolution Segmentation Algorithm was conducted to identify the variation of slope found in the study site. Then, the slope segments/objects were used to identify landform using Ruleset-Based Classification considering the image object information including object values, pattern, shape, and other parameters. The accuracy of the result was evaluated based on the percentage accuracy of the landform classification. From this study, we found that fusion-image and GEOBIA are capable of distinguishing landform elements very well with the percentage of overall accuracy is 88%. This result shows that GEOBIA has potential in identifying and classifying landform objects.
This study developed a method of satellite imagery-based land-cover/land-use mapping for Indonesia at 1:50,000 scale, but with a very detailed level of categorization. The method was developed by taking into account: (a) categorization target specified in the reference classification scheme, (b) the ecological characteristics of the Indonesian region, (c) the type of data used, and (d) the main approach that can be applied to all regions in Indonesia. A landscape ecological approach was selected, by combining digital and visual interpretation. The main data source was Landsat-8 OLI recorded in various dates of recording between 2016 and 2018, supported with SPOT-7 and Sentinel 2A imagery. Digital analysis includes geometric and radiometric corrections, pan-sharpening, and vegetation index transformation. Visual interpretation was carried out with an interpretive overlays strategy and/or land unit approach. Field work was carried out for collecting information on terrain characteristics that are relevant to the land-cover/land-use variation, to be used as a basis for re-interpretation process. Based on the developed methods, a set of land-cover/land-use maps on a scale of 1: 50,000 of the southern part of Sumatera, except Lampung Province, was delivered. It covers 247 map sheets. The interpretation accuracies have been assessed statistically, and they reached 79.54% for Bengkulu, 80.75% for Jambi, 79.2% for Riau Islands, and 81.02% for Bangka-Belitung. With a large number of classes has been mapped, i.e. over 70 categories, the accuracy levels achieved in this study were considerably high. Some notes on the results of the mapping were also included in this report.
Development of spatial databases for systematic thematic mapping is a relatively complex activity, as compared to mapping a small area with arbitrary boundary. This research was conducted in the provinces of Riau Islands, Bangka Belitung Islands, Jambi, and Bengkulu, southern Sumatera. The stages of spatial databases development involved remote sensing, GIS, and cartographic activities. A synoptic overview of the landscape was carried out prior to the spatial database development. The landscape complexity was assessed using landscape-ecological approach, which was implemented in the delineation and classification. The remote sensing process started from spatial data collection of various images with various spatial resolutions, image pre-processing, followed by image analysis and interpretation. Pan-sharpened Landsat-8 images (15 meters) were used as main data, supported by SPOT 6/7 imagery (6 meters), Sentinel-2A imagery (10 meters) and DEMNAS digital elevation model (8 meters) for particular areas. This stage gave consequences to the multi-scale analysis in the process of land-cover delineation. The GIS process comprised the stages of compiling the interpretation results to form a seamless mosaic, topology construction, coding into Indonesian Geographic Element Catalog (KUGI) standard, metadata development, followed by topology checking. Those processes aimed to achieve a single map of Sumatera at 1: 50,000 scale. The cartographic layout design was the final stage of the spatial database development, where the land-cover classes symbol was also carried out in accordance with the established standards. Some problems and solutions in the whole processes were also discussed in this paper.