Data from High Spatial Resolution Remote Sensing Imagery (HSRRSI) provides detailed information required for the recognition of surface water bodies, including the texture, geometric structure and spatial distribution of these liquid masses. The comprehensive information gathered means that the internal components of surface water bodies can be represented, and the relationship between adjacent objects are better reflected. In the context of the “Big Data Era”, we have witnessed significant improvements in recognition methods using geometric processing remote sensing data, e.g. Geographic Object-Based Image Analysis (GEOBIA). However, these methods focus mainly on bottom-up classifications of visual features to semantic categories, ignoring top-down feedback capable of optimising recognition results, and thus cannot meet the needs of current large-scale applications. Due to the powerful feature extraction and representation capability of deep learning, using a special Convolutional Neural Network (CNN) structure-based region proposal generation and object detection integrated framework greatly promotes the performance of object detection for HSRRSI; providing a new model for remote sensing water body recognition. We use the excellent “self-learning ability” of deep learning to construct a modified structure of Mask-RCNN, which integrates bottom-up and top-down processes for water recognition. Compared with traditional approaches, our method is completely data-driven without requiring prior knowledge, a novel technical procedure for water body recognition with practical engineering applications. Experimental results indicate that the method produces accurate recognition results for multi-source and multi-temporal water bodies – and can effectively avoid confusing shadows and other ground features with water bodies.
Aiming to address the problems of poor automation, low efficiency and overgeneralisation inherent in routine remote sensing image water extraction, we built a region based solution network structure based on Mask R-CNN; which is suitable for HSRRSI water recognition, object-based recognition and automatic extraction of water bodies. This method is completely data-driven and does not require prior knowledge. It improves the speed of water extraction, provides technical support for the real-time monitoring of surface water, and provides data support for water related research.
As shown in Fig.1, featuring the WorldView-3 images and GF-2 images of Tongzhou District of Beijing, we applied the modified Mask-RCNN model (trained with four different datasets) to conduct the experiments for object recognition of water bodies. The results of the experiment show that the proposed method successfully improves water recognition in four types of remote sensing imagery. For both the remote sensing of large water bodies (such as lakes and rivers) and small water bodies (such as paddy fields and small tributaries) improved results were seen, regarding the range extracted for the water bodies. Remarkably, the cross-validation of the four-image training model shows accurate results and strong generalisation ability – even if the training area is different from the test area. In addition to the extraction of water data, this method can also be applied to the accurate extraction of vegetation, desert, wetland and other thematic information – areas certainly worth further study in the future.
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