Landsat 15-m Panchromatic-Assisted Downscaling (LPAD) of the 30-m Reflective Wavelength Bands to Sentinel-2 20-m Resolution

Zhongbin Li,Hankui Zhang,Jian Li,David Roy,Lin Yan,Haiyan Huang

doi:10.3390/rs9070755

Abstract

The Landsat 15-m Panchromatic-Assisted Downscaling (LPAD) method to downscale Landsat-8 Operational Land Imager (OLI) 30-m data to Sentinel-2 multi-spectral instrument (MSI) 20-m resolution is presented. The method first downscales the Landsat-8 30-m OLI bands to 15-m using the spatial detail provided by the Landsat-8 15-m panchromatic band and then reprojects and resamples the downscaled 15-m data into registration with Sentinel-2A 20-m data. The LPAD method is demonstrated using pairs of contemporaneous Landsat-8 OLI and Sentinel-2A MSI images sensed less than 19 min apart over diverse geographic environments. The LPAD method is shown to introduce less spectral and spatial distortion and to provide visually more coherent data than conventional bilinear and cubic convolution resampled 20-m Landsat OLI data. In addition, results for a pair of Landsat-8 and Sentinel-2A images sensed one day apart suggest that image fusion should be undertaken with caution when the images are acquired under different atmospheric conditions. The LPAD source code is available at GitHub for public use.

Highlights

The Landsat-8 polar-orbiting satellite carries the Operational Land Imager (OLI) that has nine reflective wavelength (435 nm to 1384 nm) spectral bands; eight 30-m visible, near-infrared, short wave infrared, and cirrus bands, and one 15-m panchromatic band [1].The multi-spectral instrument (MSI) onboard the Sentinel-2A and Sentinel-2B polar-orbiting satellites acquires multi-spectral reflective wavelength medium resolution data with a design heritage from the Landsat and Satellite Pour l’Observation de la Terre (SPOT) sensors [2]
Rather than downscaling by conventional resampling, that we showed (Figure 3) will cause either smoothing of the downscaled results or introduce locational shifts, the Landsat-8 15-m panchromatic band was used to assist the downscaling of the Landsat-8 OLI 30-m bands to 20 m
The results of this study indicate that the Landsat 15-m Panchromatic-Assisted Downscaling (LPAD) approach can be applied to downscale all of the Landsat-8 30-m OLI bands

Summary

Introduction

The Landsat-8 polar-orbiting satellite (launched 2013) carries the Operational Land Imager (OLI) that has nine reflective wavelength (435 nm to 1384 nm) spectral bands; eight 30-m visible, near-infrared, short wave infrared, and cirrus bands, and one 15-m panchromatic band [1].The multi-spectral instrument (MSI) onboard the Sentinel-2A (launched 2015) and Sentinel-2B (launched 2017) polar-orbiting satellites acquires multi-spectral reflective wavelength medium resolution data with a design heritage from the Landsat and Satellite Pour l’Observation de la Terre (SPOT) sensors [2]. There are a number of pre-processing issues that need to be addressed before the well calibrated Landsat-8 [10,11] and Sentinel-2A [2,12] data can be used together or treated as effectively being sensed from the same sensor. These include handling the different sensor spectral response functions and correction for atmospheric effects [13,14], correction of surface reflectance anisotropy [15,16], and handling image tiling and geolocation differences [17,18,19]

Results

Discussion

Conclusion