Using high resolution DSM data to correct the terrain illumination effect in Landsat data  

Authors / CoAuthors

Li, F. | Jupp, D.L.B. | Thankappan, M.

Abstract

Terrain affects optical satellite images through both irradiance and BRDF effects. It results in the slopes facing toward the sun receiving enhanced solar irradiance and appearing brighter compared to those facing away from the sun. For anisotropic surfaces, the radiance received at the satellite sensor from a sloping surface is also affected by surface BRDF which varies with combinations of surface landcover types, sun, and satellite as well as topographic geometry. Consequently, to obtain comparable surface reflectance from satellite images covering mountainous areas, it is necessary to process the images to reduce or remove the topographic effect so that the images can be used for different purposes. The most common method of normalising for the topographic effect is by using a Digital Surface Model (DSM). However, the accuracy of the correction depends on the accuracy, scale and spatial resolution of DSM data as well as the co-registration between the DSM and satellite images. A physically based BRDF and atmospheric correction model in conjunction with the 1-second SRTM derived DSM product were used to conduct the analysis. The results show that artefacts in the DSM data can cause significant local errors in the correction. For some areas, false shadow and over corrected surface reflectance factors have been observed. In other areas, the algorithm is unable to detect shadow or retrieve an accurate surface reflectance factor. The accuracy of co-registration between satellite images and DSM data is important for the topographic correction. A mis-registration error of one or two pixels can lead to large error in the gully and ridge areas. Therefore, accurate registration for both satellite images and DSM data is necessary to ensure the accuracy of the correction. Using low resolution DSM data to correct high resolution satellite images can fail to correct some significant terrain effects.

Product Type

nonGeographicDataset

eCat Id

72607

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Keywords

• External PublicationConference Paper

( Theme )

• DEM

( Theme )

• image processing

( Theme )

• topography

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

• Published_Internal

Publication Date

2011-01-01T00:00:00

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Australian Government Security ClassificationSystem    

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Creative Commons Attribution 4.0 International Licence    

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geoscientificInformation

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Spatial Resolution

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