Extracting Built-up Areas Using Luojia-1A Nighttime Light Imageries in Wuhan, China

The extent of urban built-up areas is important to understand the current status and development of cities, also is one of the preconditions to implement the control of urban boundaries and manage the layout of urban functional space. In the past, the accuracy of urban built-up areas extraction using nighttime light imageries is often limited by data resolution and spatial scales. The Luojia-1A satellite, launched on 2018-06-02, provides a new source of nighttime light data at 130-meter resolution, which has great potential in extent extraction of urban built-up areas. In this paper, integrating Luojia-1A nighttime light data with Landsat 8 multispectral imageries and point of interest (POI), the extent of built-up areas in Wuhan, China has been extracted using human settlement index (HSI) and thresholds, respectively. The results of Luojia-1A data have been compared with results obtained from visible infrared imager radiometer suite (VIIRS)data using corresponding methods. The results show that the extracted urban extent extracted by HSI using Luojia-1A data possesses the highest accuracy, with a Kappa coefficient of 0.769. Correspondingly, the Kappa coefficient of built-up areas extent obtained by HSI method using VIIRS data is 0.702. The accuracies of urban extent extracted by integrating Luojia-1A and VIIRS images with POIs are relatively lower, which have respectively present Kappa coefficients of 0.618 and 0.574. The Kappa coefficients of extraction accuracies using simple thresholds segementation(STS) method form raw Luojia-1A and VIIRS images are 0.503 and 0.482. The results reveal that Luojia-1A nighttime light data benefit urban extent extraction for its finer resolution and more abundant spatial details, compared with its predecessors such as DMSP/OLS and VIIRS.