Current Organizations / Institutes

The organizations/institutes from the scholar's latest article

Previous Organizations / Institutes

The organizations / institutes from the scholar's other articles in the past ten years


Andrew Fletcher has a total of 51 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • Authentic learning using mobile applications and contemporary geospatial information requirements related to Environmental Science

    by Andrew Fletcher, Steven Kickbusch, Henk Huijser

    In this paper, we examine the potential of authentic learning activities and assessment to enhance the student learning experience in a standalone introductory geospatial information science module. Computer laboratory sessions form seventy-five percent of contact hours and final grade, so authentic learning used a field-based project with specified features, study area and aerial photo form the basis of assessment. The class collects all relevant geospatial information using mobile devices. Students present personally collected, and class-merged geospatial information as workplace style reports in scaffolded assessments. All submitted data are collected by the class and managed by the students. Essential skills and employment opportunities using GIS skills form the basis of authenticity of this module and guide student expectations. We evaluate outcomes through a two-year case study examining design, implementation and revision of the Unit, by using a mixed-methods approach including multiple, staged student surveys, focus groups, and student results. A focus on authenticity increased student appreciation of employability in GIS-related positions, and students reported increased motivation to learn.


  • Open Access

    Hypertemporal Imaging Capability of UAS Improves Photogrammetric Tree Canopy Models

    by Andrew Fletcher, Richard Mather

    Small uncrewed aerial systems (UASs) generate imagery that can provide detailed information regarding condition and change if the products are reproducible through time. Densified point clouds form the basic information for digital surface models and orthorectified mosaics, so variable dense point reconstruction will introduce uncertainty. Eucalyptus trees typically have sparse and discontinuous canopies with pendulous leaves that present a difficult target for photogrammetry software. We examine how spectral band, season, solar azimuth, elevation, and some processing settings impact completeness and reproducibility of dense point clouds for shrub swamp and Eucalyptus forest canopy. At the study site near solar noon, selecting near infrared camera increased projected tree canopy fourfold, and dense point features more than 2 m above ground were increased sixfold compared to red spectral bands. Near infrared (NIR) imagery improved projected and total dense features two- and threefold, respectively, compared to default green band imagery. The lowest solar elevation captured (25°) consistently improved canopy feature reconstruction in all spectral bands. Although low solar elevations are typically avoided for radiometric reasons, we demonstrate that these conditions improve the detection and reconstruction of complex tree canopy features in natural Eucalyptus forests. Combining imagery sets captured at different solar elevations improved the reproducibility of dense point clouds between seasons. Total dense point cloud features reconstructed were increased by almost 10 million points (20%) when imagery used was NIR combining solar noon and low solar elevation imagery. It is possible to use agricultural multispectral camera rigs to reconstruct Eucalyptus tree canopy and shrub swamp by combining imagery and selecting appropriate spectral bands for processing.


  • Open Access

    Correction: Alvarado, M., et al. Towards the Development of a Low Cost Airborne Sensing System to Monitor Dust Particles after Blasting at Open-Pit Mine Sites. Sensors 2015, 15, 19667–19687

    by Miguel Alvarado, Felipe Gonzalez, Andrew Fletcher, Ashray Doshi

    The author wishes to change Figure 1 and Figure 3 from his paper published in Sensors [1], doi:10.3390/s150819667, website: http://www.mdpi.com/1424-8220/15/8/19667 for Figures 1 and 2 presented in this ‘Correction’.


  • Ecotones as indicators: boundary properties in wetland-woodland transition zones

    by G. Brownstein, C. Johns, A. Fletcher, D. Pritchard, P. D. Erskine

    Ecotones, representing the transition zones between species or communities, have been suggested as focal points for detecting early shifts in vegetation composition due to anthropogenic impact. Here we examined if changes in ecotone location or properties can be used as reliable indicators of hydrological change in temperate wetland communities. We examined 38 woodland-wetland-woodland transitions, distributed across four sites with different anthropogenic disturbance histories and hydrological traits. We tested whether: 1) the ecotones are associated with environmental gradients, and 2) the location or properties of these ecotones change with disturbance history. Well-defined ecotones were associated with steep gradients in soil depth and soil moisture. Most ecotones showed a change in vegetation from hydrophytic to dryland species. There was also some evidence that in highly disturbed sites the link between ecotones and environmental gradients was less apparent. By sampling across boundaries we can bett...


  • Development of micro-UAV with integrated motion planning for open-cut mining surveillance

    by Ashray A. Doshi, Adam J. Postula, Andrew Fletcher, Surya P.N. Singh


  • Widening gap between expectations and practice in Australian minesite rehabilitation

    by David Lamb, Peter D. Erskine, Andrew Fletcher

    Summary: The basic methods for rehabilitating degraded land left after mining are reasonably well‐understood and there are examples across Australia of these being currently implemented. But there are many other situations where further research will be needed to achieve rehabilitation objectives. In addition, a number of mines are yet to embark on any sustained program of rehabilitation and there is a disappointing number of cases of mines ceasing operations before rehabilitation is completed leaving sites in a badly degraded state. Overall there appear to be surprisingly few examples in Australia of post‐ mining rehabilitation that has reached a successful conclusion. In part, this may be simply a matter of time and the problem will be resolved as more mines reach the end of their working lives. But there is an apparent trend for mines to be placed into ‘care and maintenance’ or sold to other entities, to avoid the costs of rehabilitation. Thus, we are concerned there is a widening gap between what should be possible and what is being done in practice. We review some of the experiences of rehabilitating post‐mining landscapes in Australia and conclude that problems have arisen because of (i) the inherently difficult task of restoring ecosystems at highly modified mine sites, (ii) institutional and management weaknesses and (iii) loose regulatory frameworks that allow a high level of company self‐regulation. A key problem is that the importance of rehabilitation appears to rank below that of production in the minds of many mine managers and is not accorded the level of priority that the community expects. The scale of the mining industry and its capacity to cause environmental damage means that there is a need to improve the way mine rehabilitation is currently undertaken. We suggest that this might be achieved by improving research programs as well as better institutional and regulatory arrangements. The present situation represents a major ecological and financial risk to the nation as a whole and regulatory authorities need to develop more rigorous approaches to ensure effective rehabilitation standards are achieved.


  • Testing the Power of a Wetland Vegetation Monitoring Survey Design to Detect Change Based on Visual Cover Estimates

    by Caitlin V. Johns, Gretchen Brownstein, Raymond A. J. Blick, Peter D. Erskine, Andrew T. Fletcher


  • Open Access

    Towards the Development of a Low Cost Airborne Sensing System to Monitor Dust Particles after Blasting at Open-Pit Mine Sites

    by Miguel Alvarado, Felipe Gonzalez, Andrew Fletcher, Ashray Doshi

    Blasting is an integral part of large-scale open cut mining that often occurs in close proximity to population centers and often results in the emission of particulate material and gases potentially hazardous to health. Current air quality monitoring methods rely on limited numbers of fixed sampling locations to validate a complex fluid environment and collect sufficient data to confirm model effectiveness. This paper describes the development of a methodology to address the need of a more precise approach that is capable of characterizing blasting plumes in near-real time. The integration of the system required the modification and integration of an opto-electrical dust sensor, SHARP GP2Y10, into a small fixed-wing and multi-rotor copter, resulting in the collection of data streamed during flight. The paper also describes the calibration of the optical sensor with an industry grade dust-monitoring device, Dusttrak 8520, demonstrating a high correlation between them, with correlation coefficients (R2) greater than 0.9. The laboratory and field tests demonstrate the feasibility of coupling the sensor with the UAVs. However, further work must be done in the areas of sensor selection and calibration as well as flight planning.


  • Standard survey designs drive bias in the mapping of upland swamp communities

    by D. A. Tierney, A. T. Fletcher, P. D. Erskine

    Vegetation maps are critical biodiversity planning instruments, but the classification of vegetation for mapping can be strongly biased by survey design. Standardization of survey design across different vegetation types is therefore increasingly recommended for vegetation mapping programs. However, some vegetation types have complex small‐scale vegetation patterns that are important in characterizing these vegetation types, and standard designs will often not capture these patterns. The objective of this paper was to investigate the magnitude of potential map bias that results from survey design standardization and recommend approaches to deal with this bias. We surveyed upland swamps of the Greater Blue Mountains World Heritage Area Australia using two contrasting survey designs, including the standard 400 m2 single quadrat design recommended and used by authorities. We then derived a classification for these swamps and tested the effect of survey design on this classification, species richness and the type of species detected (obligate or facultative swamp species). Species richness and species type were not significantly different among survey techniques. However, more than 40% of swamps clustered differently among survey designs. Thus, one of the 10 derived communities (which is floristically consistent with a previously mapped endangered community) was indistinct, and some individual swamps misclassified using the standard survey design. An effect of landscape position on swamp floristic patterns and a significant trend for high similarity scores among swamps surveyed with multiple small quadrats compared to the standard survey design was also determined. Australian upland swamps are classified at the global scale as shrub‐dominated wetlands, and complex floristic patterns have been recorded in shrub‐dominated wetlands in both northern and southern hemispheres. We therefore advocate either multiple survey designs or different survey standards for upland swamp communities and other vegetation types that have complex floristic patterns at small scales.