XXII ISPRS Congress 2012: Technical Commission VII

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Multivolume work

Persistent identifier:: 1663813779

Title:: XXII ISPRS Congress 2012

Sub title:: Melbourne, Australia, 25 August-1 September 2012

Year of publication:: 2013

Place of publication:: Red Hook, NY

Publisher of the original:: Curran Associates, Inc.

Identifier (digital):: 1663813779

Language:: English

Additional Notes:: Kongress-Thema: Imaging a sustainable future

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Document type:: Multivolume work

Volume

Persistent identifier:: 1663821976

Title:: Technical Commission VII

Scope:: 546 Seiten

Year of publication:: 2013

Place of publication:: Red Hook, NY

Publisher of the original:: Curran Associates, Inc.

Identifier (digital):: 1663821976

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(39,B7)

Language:: English

Additional Notes:: Erscheinungsdatum des Originals ist ermittelt.; Literaturangaben

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 22., 2012, Melbourne; International Society for Photogrammetry and Remote Sensing

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2019

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: [VII/3: INFORMATION EXTRACTION FROM HYPERSPECTRAL DATA]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: MAPPING THE WETLAND VEGETATION COMMUNITIES OF THE AUSTRALIAN GREAT ARTESIAN BASIN SPRINGS USING SAM, MTMF AND SPECTRALLY SEGMENTED PCA HYPERSPECTRAL ANALYSES D. C. White, M. M. Lewis

Document type:: Multivolume work

Structure type:: Chapter

springs has become uncertain as demands on this iconic groundwater resource increase. The impacts of existing water extractions for mining and pastoral activities are unknown. This situation is compounded by the likelihood of future increasing demand for extractions. Despite their importance, GAB springs have received scant inventory and documentation of their vegetation extent, distribution and composition. Hyperspectral remote sensing provides the necessary spectral and spatial detail to discriminate wetland vegetation communities and has shown great potential in previous studies for mapping wetlands vegetation (Torbick and Becker, 2009; Hestir et al., 2008; Zomer et al., 2009). This technology will enable accurate and repeatable baseline and longer-term mapping of these remote and spatially disparate groundwater dependent ecosystems (GDEs) to be achieved. The objectives of this paper are to discriminate the spatial extent and distribution of key spring wetland vegetation communities associated with the GAB springs evaluating Spectral Angle Mapper (SAM), Mixture Tuned Matched Filtering (MTMF) and Spectrally Segmented Principal Component Analysis (PCA) hyperspectral techniques. In addition, to determine if the hyperspectral techniques developed can be applied at a number of sites representative of the range of spring formations, their floristic and geomorphic diversity and at two temporal intervals (March 2009 and April 2011). 1.2 Study area The GAB springs found in South Australia (SA) are located along the western margin of the GAB and are formed from the natural outflow of groundwater. The GAB springs surface expression is composed of wetland vegetation, saline flats and carbonaceous substrate. The wetland plant communities of GAB springs vary between spring groups (cluster of springs sharing the same water source) and complexes (clusters of spring groups which share the same geomorphological settings), some of which are rare, relic and endemic to this region. This paper focuses on three sites Hermit Hill Springs complex (latitude 29.60° S and longitude 137.41° E), Freeling Springs, Mount Denison complex (latitude 28.06° S and longitude 135.91° E), and Dalhousie Springs complex (latitude 26.45° S and longitude 135.51° E). The three sites are representative of GAB springs within SA. The sites also differ in their geomorphic setting, vegetation community composition, spatial extent and distribution of springs. 2. MATERIALS AND METHODS 2.1 Image Data Two epochs of HyMap airborne hyperspectral mosaicked image cubes were captured for this research in March 2009 and April 2011. The two epochs of HyMap imagery were captured under dry antecedent conditions (March 2009) and wet antecedent conditions (April 2011). The HyMap imagery is composed of 126 wavebands with a bandwidth of ~15 nm and wavelength range of 450 — 2,500nm, a ~3 m ground sampling distance (GSD), and swath width of 1.5 km. The raw HyMap imagery was radiometrically corrected along with geometric correction and colour balancing of swaths to form a seamless mosaic (Kruse et al., 2009; Cocks et al., 1998). Colour digital aerial photography at 30 cm GSD was acquired concurrently with the HyMap imagery. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B7, 2012 XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia Results discussed in this paper focus on the March 2009 baseline image capture for all three sites. More detailed comparison of changes between March 2009 and April 2011 is focused on the Hermit Hill springs complex. 2.2 Field data The image acquisition coincided with a field campaign of spectroradiometry measurements and a botanical survey, which included recording vegetation cover and composition within 9 x 9 m sample plots representative of the range of spring vegetation types and cover. The spatial locations of field measurements were recorded with GPS. 2.3 Image processing To identify key wavebands which have the greatest capability to discriminate vegetation communities of the GAB springs and surrounding area three hyperspectral data reduction techniques were employed: (i) the Minimum Noise Transform (MNF); (ii) the Pixel Purity Index (PPI); and (iii) Spectrally Segmented PCA (SSPCA). SSPCA was applied to NDVI-masked vegetation portions of the HyMap imagery with wavelength regions spectrally segmented for the VIS-NIR (450-1,350 nm), SWIR 1 (1,400-1,800 nm) and SWIR 2 (1,950-2,480 nm). The pure pixels identified from the SAM and MTMF analyses were interactively verified as specific spring vegetation communities using spatial location and attribute data collected from the botanical survey plots overlayed onto colour composites of the HyMap imagery, MNF and PPI output images. The resulting pure endmember image pixels of the vegetation communities identified were used as target spectra for input into the SAM and MTMF algorithms which identify pixels within the HyMap image which are spectrally similar to the target spectra. 3. RESULTS AND DISCUSSION The resulting SAM and MTMF output images of the identified target vegetation communities are currently being validated through formal accuracy assessment using field observations and digital colour aerial photography. Spring wetland vegetation communities successfully discriminated include low lying reeds and sedges along spring tails (Baumea spp., Cyperus spp., Fimbristylis sp., Gahnia trifida sp.), dense homogenous stands of Phragmites australis reeds and White Tea Tree (Melaleuca glomerata sp.). In addition sporadic patches of salt couch grass (Sparabolus spp.), Samphire shrublands (Haloscarcia sp. and Sarcocrina sp.) and Sea Heath (Frankenia sp.) which fringe the springs were also discriminated. VIS-NIR PCs 2, 3 and 9 identified key vegetation discrimination wavelength features, in particular, the green peak at 555 nm, chlorophyll absorption feature at 685 nm, VIS-NIR and red-edge contrasts. The SWIR 1 PC 3 mapped Phragmites australis, with notable loadings at wavelengths 1,450, 1,645- 1,715, 1815, and 1,825 nm associated with water, lignin, and cellulose absorptions, respectively. The SWIR 2 region revealed little spectral variation (White and Lewis, 2010). Differences between March 2009 and April 2011 HyMap image captures focused on the Hermit Hill springs complex. The extent and distribution of spring wetland vegetation communities varied between the two image dates. Most notable were decreases in Phragmites australis reeds in contrast with

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