Remote sensing-based approaches to lithological mapping are traditionally pixel-oriented, with classification performed on either a per-pixel or sub-pixel basis with complete disregard for contextual information about neighbouring pixels. However, intra-class variability due to heterogeneous surface cover (i.e., vegetation and soil) or regional variations in mineralogy and chemical composition can result in the generation of unrealistic, generalised lithological maps that exhibit the “salt-and-pepper” artefact of spurious pixel classifications, as well as poorly defined contacts. In this study, an object-based image analysis (OBIA) approach to lithological mapping is evaluated with respect to its ability to overcome these issues by instead classifying groups of contiguous pixels (i.e., objects). Due to significant vegetation cover in the study area, the OBIA approach incorporates airborne multispectral and LiDAR data to indirectly map lithologies by exploiting associations with both topography and vegetation type. The resulting lithological maps were assessed both in terms of their thematic accuracy and ability to accurately delineate lithological contacts. The OBIA approach is found to be capable of generating maps with an overall accuracy of 73.5% through integrating spectral and topographic input variables. When compared to equivalent per-pixel classifications, the OBIA approach achieved thematic accuracy increases of up to 13.1%, whilst also reducing the “salt-and-pepper” artefact to produce more realistic maps. Furthermore, the OBIA approach was also generally capable of mapping lithological contacts more accurately. The importance of optimising the segmentation stage of the OBIA approach is also highlighted. Overall, this study clearly demonstrates the potential of OBIA for lithological mapping applications, particularly in significantly vegetated and heterogeneous terrain.
Cheffins’ first property auction of 2019 achieved an 82 per cent sale rate and strong prices on 13th March in Cambridge.Barns with development potential had the most active interest, including a 17th century Grade II listed barn set in four acres in Great Yeldham, near Toppesfield, Essex, which sold for £160,000. Similarly, a detached agricultural barn offered in Fenstanton, near Cambridge, with planning permission for conversion into two large residential dwellings made £294,000.Income-generating properties also were popular. The highest price achieved on the day was £435,000 for a development site on Argyle Street, central Cambridge which includes two storage spaces and a workshop close to Mill Road.The more unusual lots also sold well. For example, 4.75 acres of mature woodland, suitable for amenity use near Wethersfield, Essex, was sold for £63,000, well over its guide price of £45,000.Ian Kitson, Director, Cheffins said, “The March sale showed that there is still good demand for sensibly priced property throughout the region, despite the current political landscape. This shows the growing popularity of the auction room as a go-to situation to purchase property and the confidence in the regional market.”The next property auction is on Wednesday 19th June.Ian Kitson barns Cheffins Cheffins auction Director May 29, 2019The NegotiatorWhat’s your opinion? Cancel replyYou must be logged in to post a comment.Please note: This is a site for professional discussion. Comments will carry your full name and company.This site uses Akismet to reduce spam. Learn how your comment data is processed.Related articles BREAKING: Evictions paperwork must now include ‘breathing space’ scheme details30th April 2021 City dwellers most satisfied with where they live30th April 2021 Hong Kong remains most expensive city to rent with London in 4th place30th April 2021 Home » News » Agencies & People » Market confidence shown at Cheffins’ Auction previous nextAgencies & PeopleMarket confidence shown at Cheffins’ AuctionThe Negotiator29th May 20190182 Views