Andrew Mcgrath | Flinders University of South Australia (original) (raw)

Papers by Andrew Mcgrath

Proceedings of SPIE, Sep 30, 2004

The Anglo-Australian Observatory is currently designing a new fibre positioner for the UK Schmidt... more The Anglo-Australian Observatory is currently designing a new fibre positioner for the UK Schmidt Telescope. The instrument will have 2250 fibres, positioned with sub-arcsecond accuracy across a six degree field of view, and will have a reconfiguration time of one minute. The instrument is to enable the RAVE survey of high precision abundances and velocities for up to 50 million stars. The design is largely adapted from the AAO's FMOS-Echidna fibre positioner for Subaru. New design challenges for Ukidna include the enormous number of fibres, the large focal surface, and the field curvature of the Schmidt telescope. These features are mostly shared with the expected needs of future primefocus multi-fibre systems on 8-30m class telescopes. We present details and performance of the multi-actuator design.

Zenodo (CERN European Organization for Nuclear Research), Sep 15, 2021

Land

A disjunct population of red stringybark (Eucalyptus macrorhyncha) trees in South Australia is ex... more A disjunct population of red stringybark (Eucalyptus macrorhyncha) trees in South Australia is experiencing increasing amounts of dieback. Because the population is considered vulnerable to extinction, we investigated spatiotemporal vegetation changes, quantified the extent of dieback, and determined how topography influences dieback using aerial and satellite imagery. Classification of vegetation health status using hyperspectral aerial imagery indicated that 37% (accuracy = 0.87 Kappa) of the population was unhealthy and potentially experiencing dieback. When correlating this classification with a digital terrain model (DTM), the aspect and amount of solar radiation had the strongest relationship with the presence of unhealthy vegetation. PlanetScope satellite-derived, and spectral index-based analysis indicated that 7% of the red stringybark population experienced negative vegetation health changes during a five-year period (2017–2022), with positive vegetation health changes (9....

Fourth International Conference on Remote Sensing and Geoinformation of the Environment (RSCy2016), 2016

Visibility and clarity of remotely sensed images acquired by consumer grade DSLR cameras, mounted... more Visibility and clarity of remotely sensed images acquired by consumer grade DSLR cameras, mounted on an unmanned aerial vehicle or a manned aircraft, are critical factors in obtaining accurate and detailed information from any area of interest. The presence of substantial haze, fog or gaseous smoke particles; caused, for example, by an active bushfire at the time of data capture, will dramatically reduce image visibility and quality. Although most modern hyperspectral imaging sensors are capable of capturing a large number of narrow range bands of the shortwave and thermal infrared spectral range, which have the potential to penetrate smoke and haze, the resulting images do not contain sufficient spatial detail to enable locating important objects or assist search and rescue or similar applications which require high resolution information. We introduce a new method for penetrating gaseous smoke without compromising spatial resolution using a single modified DSLR camera in conjunction with image processing techniques which effectively improves the visibility of objects in the captured images. This is achieved by modifying a DSLR camera and adding a custom optical filter to enable it to capture wavelengths from 480-1200nm (R, G and Near Infrared) instead of the standard RGB bands (400-700nm). With this modified camera mounted on an aircraft, images were acquired over an area polluted by gaseous smoke from an active bushfire. Processed data using our proposed method shows significant visibility improvements compared with other existing solutions.

IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium, 2018

A fundamental limitation of current soil moisture remote sensing technology is that can only prov... more A fundamental limitation of current soil moisture remote sensing technology is that can only provide moisture information on the top 5 cm layer of soil at most, being one-tenth to one-quarter of the wavelength (21 cm at L-band; 1.4 GHz) using the current SMAP and SMOS soil moisture dedicated missions of NASA and ESA. Consequently, we have developed an airborne passive microwave sensing capability at P-band to develop a new state-of-the-art satellite concept that will provide soil moisture data for the top 10 cm layer of soil using radiometer observations at P-band (40 cm; 750 MHz). Not only would P-band provide soil moisture information on a soil layer thickness that more closely relates to that affecting crop and pasture growth, but it is expected to produce greater spatial coverage with improved accuracy to that from L-band. This is because P-band should be less affected by surface roughness conditions and have a reduced attenuation by the overlaying vegetation. This paper describ...

Scientific Reports

Seagrasses are regarded as indicators and first line of impact for anthropogenic activities affec... more Seagrasses are regarded as indicators and first line of impact for anthropogenic activities affecting the coasts. The underlying mechanisms driving seagrass cover however have been mostly studied on small scales, making it difficult to establish the connection to seagrass dynamics in an impacted seascape. In this study, hyperspectral airborne imagery, trained from field surveys, was used to investigate broadscale seagrass cover and genus distribution along the coast of Adelaide, South Australia. Overall mapping accuracy was high for both seagrass cover (98%, Kappa = 0.93), and genus level classification (85%, Kappa = 0.76). Spectral separability allowed confident genus mapping in waters up to 10 m depth, revealing a 3.5 ratio between the cover of the dominant Posidonia and Amphibolis. The work identified the absence of Amphibolis in areas historically affected by anthropogenic discharges, which occasionally contained Posidonia and might be recovering. The results suggest hyperspectr...

This appendix is comprised of the computer program ‘SNRCalc ’ used to investigate the signalto-no... more This appendix is comprised of the computer program ‘SNRCalc ’ used to investigate the signalto-noise ratio of a pulsed Doppler lidar system. It is described in Chapter 2 and was used to derive the model results appearing in that chapter. The program runs under Windows 95/98 on a PC, and may be found on the accompanying CD-ROM in a subdirectory called ‘APPEND_A’. Animations of output of this program, discussed in Chapter 2, are also found in the same directory. To view these, open the file ‘animate.htm ’ in a web browser such as Netscape or

Geoscience Australia in collaboration with the CO2CRC hosted three controlled subsurface release ... more Geoscience Australia in collaboration with the CO2CRC hosted three controlled subsurface release experiments of CO2 during 2012 to 2013 at an agricultural research station managed by CSIRO Plant Industry Canberra. The facility is designed to simulate surface emissions of CO2 and other greenhouse gases from the soil into the atmosphere, and has deployed a range of near-surface monitoring techniques in the pursuit of improving detection and quantification methods and technologies. This product, which encompasses 4 geodatabases, a metadata report and a data dictionary, presents all the data collected during the experiments from over 10 research organisations, and is made to use with ESRI ArcGIS software. The intention of this data release is make the data available for comparison with measurements taken at other controlled release experiments, CO2 storage projects and natural analogues. This will hopefully facilitate the further development of greenhouse gas monitoring technologies, me...

Paper 30aTwo shallow sub-surface CO2 controlled release experiments were conducted at the Ginnind... more Paper 30aTwo shallow sub-surface CO2 controlled release experiments were conducted at the Ginninderra test site during 2012. The theme of the first experiment was CO2 detection in the soil and surface emissions quantification. The theme for the second experiment was investigating sub-surface migration and broad scale detection technologies. Our objective overall is to design cheaper monitoring technologies to evaluate leakage and environmental impact in the shallow sub-surface. Over 10 different monitoring techniques were evaluated at the site against a known CO2 release. These included soil gas, soil CO2 flux, soil analysis, eddy covariance, atmospheric tomography, noble gas tracers, ground penetrating radar, electromagnetic surveys, airborne hyperspectral, in-field phenotyping (thermal, hyperspectral and 3D imaging), and microbial soil genomics. Technique highlights and an assessment of the implications for large scale storage are presented in the following corresponding talks.A. Feitz, H. Berko, C. Kemp, C. Jenkins, U. Schacht, R. Noble, S. Zegelin, T Kuske, A. McGrath, R. Pevzner, I. Schroder, X. Sirault and J. Jimenez-Bern

IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium, 2018

Soil moisture measurement using L-band radiometry is now widely accepted as the state-of-art remo... more Soil moisture measurement using L-band radiometry is now widely accepted as the state-of-art remote sensing approach, and has been adopted by both the SMOS and SMAP soil moisture dedicated satellite missions. However, it suffers from the shallow depth of its soil moisture measurement, and the confounding effects of vegetation and soil roughness on soil moisture retrieval. P-band, which is a longer wavelength measurement, provides the potential to retrieve deeper soil moisture information, and to do so more accurately due to reduced soil roughness and vegetation effects. This paper presents some pioneering work on the use of P-band for soil moisture retrieval. The Polarimetric P-band Multibeam Radiometer (PPMR) used in this research operates at 740 MHz / wavelength of 40 cm. It is used together with the Polarimetric L-band Multibeam Radiometer (PLMR) which operates at 1.4 GHz / wavelength of 21 cm. The PPMR and PLMR are mounted onto a 10m high tower in an agricultural farm located at Cora Lynn, Victoria. This paper outlines the initial set up for the study and the experimental plan for understanding PPMR's performance, along with some initial data.

IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium, 2020

Soil Moisture is an important geophysical variable that needs reliable quantification for applica... more Soil Moisture is an important geophysical variable that needs reliable quantification for applications in hydrology, meteorology and agriculture. L-band radiometry has proved to be one of the best methods in soil moisture estimation using microwave signals. However, they provide measurements that correspond to a shallow depth of 5 cm and are also affected by the presence of overlaying vegetation and roughness. In contrast, P-band radiometry is expected to provide moisture information on a deeper layer of soil. Moreover, these lower frequency measurements are expected to be less affected by soil roughness and vegetation contributions. Consequently, this pilot study uses the Polarimetric P-band Multibeam Radiometer (PPMR) at 740 MHz to evaluate the response of the P-band radiometer over a realistic range of surface conditions at the field scale. A preliminary framework of P-band Microwave Emission of the Biosphere (P-MEB) has been developed as a forward model that simulates brightness temperature from soil moisture and other ancillary data collected from the field. This paper presents the model for the bare soil condition observed during June 2018 to August 2018. The results show that H-polarised PPMR data has better correlation to the soil moisture over a depth of 10 cm than the V-polarized PPMR data. A model is under improvement by incorporating a more suitable effective temperature formulation.

Scientific Reports, 2021

An amendment to this paper has been published and can be accessed via a link at the top of the pa... more An amendment to this paper has been published and can be accessed via a link at the top of the paper.

2019 URSI Asia-Pacific Radio Science Conference (AP-RASC), 2019

IEEE Geoscience and Remote Sensing Letters

High resolution aerial images of the hyperspectral infrared bands promise important advances in e... more High resolution aerial images of the hyperspectral infrared bands promise important advances in environmental and ecological research [1]. In 2012 and 2013, an experiment was conducted in Australia to determine the impact of continual sub-surface release of carbon dioxide on the growth of agricultural crops. Airborne hyperspectral imagery was one of the techniques employed to detect the effects of the CO 2. However, standard hyperspectral analysis techniques and indices were unable to distinguish between plants affected by the CO 2 and those stressed by other factors [1]. The hyperspectral data of the test plot are in 488 bands from 400 to 2500nm [2]. They are georeferenced and resampled onto a 0.5m resolution grid [1]. Here we report an application of Data Mining techniques [3] for a deeper analysis of the data to seek for a hyperspectral signature able to identify the CO 2 ,-stressed vegetation specifically. A careful preprocessing allowed a data reduction by a factor of ca. 10. The remaining spectral bands were clustered using an emergent self-organizing map (ESOM) [4]. The clusters obtained could be related to the location of the healthy and stressed plants. This work shows the suitability and efficacy of modern Data Mining and Knowledge Discovery techniques for hyperspectral images.

Proceedings of SPIE, Sep 30, 2004

The Anglo-Australian Observatory is currently designing a new fibre positioner for the UK Schmidt... more The Anglo-Australian Observatory is currently designing a new fibre positioner for the UK Schmidt Telescope. The instrument will have 2250 fibres, positioned with sub-arcsecond accuracy across a six degree field of view, and will have a reconfiguration time of one minute. The instrument is to enable the RAVE survey of high precision abundances and velocities for up to 50 million stars. The design is largely adapted from the AAO's FMOS-Echidna fibre positioner for Subaru. New design challenges for Ukidna include the enormous number of fibres, the large focal surface, and the field curvature of the Schmidt telescope. These features are mostly shared with the expected needs of future primefocus multi-fibre systems on 8-30m class telescopes. We present details and performance of the multi-actuator design.

Zenodo (CERN European Organization for Nuclear Research), Sep 15, 2021

Land

A disjunct population of red stringybark (Eucalyptus macrorhyncha) trees in South Australia is ex... more A disjunct population of red stringybark (Eucalyptus macrorhyncha) trees in South Australia is experiencing increasing amounts of dieback. Because the population is considered vulnerable to extinction, we investigated spatiotemporal vegetation changes, quantified the extent of dieback, and determined how topography influences dieback using aerial and satellite imagery. Classification of vegetation health status using hyperspectral aerial imagery indicated that 37% (accuracy = 0.87 Kappa) of the population was unhealthy and potentially experiencing dieback. When correlating this classification with a digital terrain model (DTM), the aspect and amount of solar radiation had the strongest relationship with the presence of unhealthy vegetation. PlanetScope satellite-derived, and spectral index-based analysis indicated that 7% of the red stringybark population experienced negative vegetation health changes during a five-year period (2017–2022), with positive vegetation health changes (9....

Fourth International Conference on Remote Sensing and Geoinformation of the Environment (RSCy2016), 2016

Visibility and clarity of remotely sensed images acquired by consumer grade DSLR cameras, mounted... more Visibility and clarity of remotely sensed images acquired by consumer grade DSLR cameras, mounted on an unmanned aerial vehicle or a manned aircraft, are critical factors in obtaining accurate and detailed information from any area of interest. The presence of substantial haze, fog or gaseous smoke particles; caused, for example, by an active bushfire at the time of data capture, will dramatically reduce image visibility and quality. Although most modern hyperspectral imaging sensors are capable of capturing a large number of narrow range bands of the shortwave and thermal infrared spectral range, which have the potential to penetrate smoke and haze, the resulting images do not contain sufficient spatial detail to enable locating important objects or assist search and rescue or similar applications which require high resolution information. We introduce a new method for penetrating gaseous smoke without compromising spatial resolution using a single modified DSLR camera in conjunction with image processing techniques which effectively improves the visibility of objects in the captured images. This is achieved by modifying a DSLR camera and adding a custom optical filter to enable it to capture wavelengths from 480-1200nm (R, G and Near Infrared) instead of the standard RGB bands (400-700nm). With this modified camera mounted on an aircraft, images were acquired over an area polluted by gaseous smoke from an active bushfire. Processed data using our proposed method shows significant visibility improvements compared with other existing solutions.

IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium, 2018

A fundamental limitation of current soil moisture remote sensing technology is that can only prov... more A fundamental limitation of current soil moisture remote sensing technology is that can only provide moisture information on the top 5 cm layer of soil at most, being one-tenth to one-quarter of the wavelength (21 cm at L-band; 1.4 GHz) using the current SMAP and SMOS soil moisture dedicated missions of NASA and ESA. Consequently, we have developed an airborne passive microwave sensing capability at P-band to develop a new state-of-the-art satellite concept that will provide soil moisture data for the top 10 cm layer of soil using radiometer observations at P-band (40 cm; 750 MHz). Not only would P-band provide soil moisture information on a soil layer thickness that more closely relates to that affecting crop and pasture growth, but it is expected to produce greater spatial coverage with improved accuracy to that from L-band. This is because P-band should be less affected by surface roughness conditions and have a reduced attenuation by the overlaying vegetation. This paper describ...

Scientific Reports

Seagrasses are regarded as indicators and first line of impact for anthropogenic activities affec... more Seagrasses are regarded as indicators and first line of impact for anthropogenic activities affecting the coasts. The underlying mechanisms driving seagrass cover however have been mostly studied on small scales, making it difficult to establish the connection to seagrass dynamics in an impacted seascape. In this study, hyperspectral airborne imagery, trained from field surveys, was used to investigate broadscale seagrass cover and genus distribution along the coast of Adelaide, South Australia. Overall mapping accuracy was high for both seagrass cover (98%, Kappa = 0.93), and genus level classification (85%, Kappa = 0.76). Spectral separability allowed confident genus mapping in waters up to 10 m depth, revealing a 3.5 ratio between the cover of the dominant Posidonia and Amphibolis. The work identified the absence of Amphibolis in areas historically affected by anthropogenic discharges, which occasionally contained Posidonia and might be recovering. The results suggest hyperspectr...

This appendix is comprised of the computer program ‘SNRCalc ’ used to investigate the signalto-no... more This appendix is comprised of the computer program ‘SNRCalc ’ used to investigate the signalto-noise ratio of a pulsed Doppler lidar system. It is described in Chapter 2 and was used to derive the model results appearing in that chapter. The program runs under Windows 95/98 on a PC, and may be found on the accompanying CD-ROM in a subdirectory called ‘APPEND_A’. Animations of output of this program, discussed in Chapter 2, are also found in the same directory. To view these, open the file ‘animate.htm ’ in a web browser such as Netscape or

Geoscience Australia in collaboration with the CO2CRC hosted three controlled subsurface release ... more Geoscience Australia in collaboration with the CO2CRC hosted three controlled subsurface release experiments of CO2 during 2012 to 2013 at an agricultural research station managed by CSIRO Plant Industry Canberra. The facility is designed to simulate surface emissions of CO2 and other greenhouse gases from the soil into the atmosphere, and has deployed a range of near-surface monitoring techniques in the pursuit of improving detection and quantification methods and technologies. This product, which encompasses 4 geodatabases, a metadata report and a data dictionary, presents all the data collected during the experiments from over 10 research organisations, and is made to use with ESRI ArcGIS software. The intention of this data release is make the data available for comparison with measurements taken at other controlled release experiments, CO2 storage projects and natural analogues. This will hopefully facilitate the further development of greenhouse gas monitoring technologies, me...

Paper 30aTwo shallow sub-surface CO2 controlled release experiments were conducted at the Ginnind... more Paper 30aTwo shallow sub-surface CO2 controlled release experiments were conducted at the Ginninderra test site during 2012. The theme of the first experiment was CO2 detection in the soil and surface emissions quantification. The theme for the second experiment was investigating sub-surface migration and broad scale detection technologies. Our objective overall is to design cheaper monitoring technologies to evaluate leakage and environmental impact in the shallow sub-surface. Over 10 different monitoring techniques were evaluated at the site against a known CO2 release. These included soil gas, soil CO2 flux, soil analysis, eddy covariance, atmospheric tomography, noble gas tracers, ground penetrating radar, electromagnetic surveys, airborne hyperspectral, in-field phenotyping (thermal, hyperspectral and 3D imaging), and microbial soil genomics. Technique highlights and an assessment of the implications for large scale storage are presented in the following corresponding talks.A. Feitz, H. Berko, C. Kemp, C. Jenkins, U. Schacht, R. Noble, S. Zegelin, T Kuske, A. McGrath, R. Pevzner, I. Schroder, X. Sirault and J. Jimenez-Bern

IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium, 2018

Soil moisture measurement using L-band radiometry is now widely accepted as the state-of-art remo... more Soil moisture measurement using L-band radiometry is now widely accepted as the state-of-art remote sensing approach, and has been adopted by both the SMOS and SMAP soil moisture dedicated satellite missions. However, it suffers from the shallow depth of its soil moisture measurement, and the confounding effects of vegetation and soil roughness on soil moisture retrieval. P-band, which is a longer wavelength measurement, provides the potential to retrieve deeper soil moisture information, and to do so more accurately due to reduced soil roughness and vegetation effects. This paper presents some pioneering work on the use of P-band for soil moisture retrieval. The Polarimetric P-band Multibeam Radiometer (PPMR) used in this research operates at 740 MHz / wavelength of 40 cm. It is used together with the Polarimetric L-band Multibeam Radiometer (PLMR) which operates at 1.4 GHz / wavelength of 21 cm. The PPMR and PLMR are mounted onto a 10m high tower in an agricultural farm located at Cora Lynn, Victoria. This paper outlines the initial set up for the study and the experimental plan for understanding PPMR's performance, along with some initial data.

IGARSS 2020 - 2020 IEEE International Geoscience and Remote Sensing Symposium, 2020

Soil Moisture is an important geophysical variable that needs reliable quantification for applica... more Soil Moisture is an important geophysical variable that needs reliable quantification for applications in hydrology, meteorology and agriculture. L-band radiometry has proved to be one of the best methods in soil moisture estimation using microwave signals. However, they provide measurements that correspond to a shallow depth of 5 cm and are also affected by the presence of overlaying vegetation and roughness. In contrast, P-band radiometry is expected to provide moisture information on a deeper layer of soil. Moreover, these lower frequency measurements are expected to be less affected by soil roughness and vegetation contributions. Consequently, this pilot study uses the Polarimetric P-band Multibeam Radiometer (PPMR) at 740 MHz to evaluate the response of the P-band radiometer over a realistic range of surface conditions at the field scale. A preliminary framework of P-band Microwave Emission of the Biosphere (P-MEB) has been developed as a forward model that simulates brightness temperature from soil moisture and other ancillary data collected from the field. This paper presents the model for the bare soil condition observed during June 2018 to August 2018. The results show that H-polarised PPMR data has better correlation to the soil moisture over a depth of 10 cm than the V-polarized PPMR data. A model is under improvement by incorporating a more suitable effective temperature formulation.

Scientific Reports, 2021

An amendment to this paper has been published and can be accessed via a link at the top of the pa... more An amendment to this paper has been published and can be accessed via a link at the top of the paper.

2019 URSI Asia-Pacific Radio Science Conference (AP-RASC), 2019

IEEE Geoscience and Remote Sensing Letters

High resolution aerial images of the hyperspectral infrared bands promise important advances in e... more High resolution aerial images of the hyperspectral infrared bands promise important advances in environmental and ecological research [1]. In 2012 and 2013, an experiment was conducted in Australia to determine the impact of continual sub-surface release of carbon dioxide on the growth of agricultural crops. Airborne hyperspectral imagery was one of the techniques employed to detect the effects of the CO 2. However, standard hyperspectral analysis techniques and indices were unable to distinguish between plants affected by the CO 2 and those stressed by other factors [1]. The hyperspectral data of the test plot are in 488 bands from 400 to 2500nm [2]. They are georeferenced and resampled onto a 0.5m resolution grid [1]. Here we report an application of Data Mining techniques [3] for a deeper analysis of the data to seek for a hyperspectral signature able to identify the CO 2 ,-stressed vegetation specifically. A careful preprocessing allowed a data reduction by a factor of ca. 10. The remaining spectral bands were clustered using an emergent self-organizing map (ESOM) [4]. The clusters obtained could be related to the location of the healthy and stressed plants. This work shows the suitability and efficacy of modern Data Mining and Knowledge Discovery techniques for hyperspectral images.