Progress toward the sustainable development of world cultural heritage sites facing land-cover changes

The quantification of the extent and dynamics of land-use changes is a key metric employed to assess the progress toward several Sustainable Development Goals(SDGs)that form part of the United Nations 2030 Sustainable Development Agenda.In terms of anthropogenic factors threatening the conservation of heritage properties,such a metric aids in the assessment of achievements toward heritage sustainability solving the problem of insufficient data availability.Therefore,in this study,589 cultural World Heritage List(WHL)properties from 115 countries were analyzed,encompassing globally distributed and statistically significant samples of“monuments and groups of buildings”(73.2%),“sites”(19.3%),and“cultural landscapes”(7.5%).Land-cover changes in the WHL properties between 2015 and 2020 were automatically extracted from big data collections of high-resolution satellite imagery accessed via Google Earth Engine using intelligent remote sensing classification.Sustainability indexes(SIs)were estimated for the protection zones of each property,and the results were employed,for the first time,to assess the progress of each country toward SDG Target 11.4.Despite the apparent advances in SIs(10.4%),most countries either exhibited steady(20.0%)or declining(69.6%)SIs due to limited cultural investigations and enhanced negative anthropogenic disturbances.This study confirms that land-cover changes are among serious threats for heritage conservation,with heritage in some countries wherein the need to address this threat is most crucial,and the proposed spatiotemporal monitoring approach is recommended.

A novel image-fusion method based on the un-mixing of mixed MS sub-pixels regarding high-resolution DSM

A major reason for the spectral distortions of fused images generated by current image-fusion methods is that the fused versions of mixed multispectral(MS)sub-pixels(MSPs)corresponding to panchromatic(PAN)pure pixels remain mixed.The MSPs can be un-mixed spectrally to pure pixels having the same land cover classes in a fine classification map during the fusion process.Since it is difficult to produce such a land cover classification map using only MS and PAN images,a Digital Surface Model(DSM)derived from airborne Light Detection And Ranging data were employed in this study to facilitate the classification.In a novel fusion method proposed in this paper,MSPs near and across boundaries between vegetation and non-vegetation are identified using MS,PAN,and normalized Digital Surface Model(nDSM).The identified MSPs then are fused to pure pixels with respect to the corresponding land cover class in the classification map.In a test on WorldView-2 images over an urban area and the corresponding nDSM,the fused image generated by the proposed method was visually and quantitatively compared with fused images obtained using common image-fusion methods.The fused images generated by the proposed method yielded minimal spectral distortions and sharpened boundaries between vegetation and non-vegetation.

Remote sensing-based deformation monitoring of pagodas at the Bagan cultural heritage site,Myanmar

As a World Cultural Heritage site with sacred landscape featuring an exceptional range of Buddhist art and architecture,much attention has been focused on the sustainable development of Bagan(Myanmar).Particularly,the monitoring of landscape surface subsidence and monument instability is of great importance to the protection and development planning of the Bagan heritage site.In this study,we applied high resolution TerraSAR-X imagery acquired from 2019 to 2020 for deformation monitoring based on the small baseline subset(SBAS)and persistent scatterer synthetic aperture radar interferometry(PSInSAR)approaches.We identified several hotspots and pagodas with displacement anomalies linked to land cover change and previous earthquakes.The cross comparison between SBAS and PSInSAR and the precision of height estimates derived by PSInSAR indicated a millimetric precision of the derived deformation products.The combination of the two multi-temporal SAR interferometry approaches satisfies the two-scale monitoring requirements from landscapes to monuments,particularly for large-scale World Heritage sites.The non-contact monitoring method has potential when traditional methods using field accessibility and surveillance are constrained.

Geostatistical approaches to refinement of digital elevation data

Data refinement refers to the processes by which a dataset’s resolution,in particular,the spatial one,is refined,and is thus synonymous to spatial downscaling.Spatial resolution indicates measurement scale and can be seen as an index for regular data support.As a type of change of scale,data refinement is useful for many scenarios where spatial scales of existing data,desired analyses,or specific applications need to be made commensurate and refined.As spatial data are related to certain data support,they can be conceived of as support-specific realizations of random fields,suggesting that multivariate geostatistics should be explored for refining datasets from their coarser-resolution versions to the finerresolution ones.In this paper,geostatistical methods for downscaling are described,and were implemented using GTOPO30 data and sampled Shuttle Radar Topography Mission data at a site in northwest China,with the latter’s majority grid cells used as surrogate reference data.It was found that proper structural modeling is important for achieving increased accuracy in data refinement;here,structural modeling can be done through proper decomposition of elevation fields into trends and residuals and thereafter.It was confirmed that effects of semantic differences on data refinement can be reduced through properly estimating and incorporating biases in local means.