Anthony K. Milne

A review of remote sensing technology in support of the Kyoto Protocol

This paper presents an overview of the role of remote sensing technology in the context of the United Nations Framework Convention on Climate Change (UNFCCC) Kyoto Protocol and is based largely on discussions held at an international workshop in MI, USA, and the report that followed [A. Rosenqvist, M. Imhoff, T. Milne, C. Dobson (Eds.), Remote Sensing and the Kyoto Protocol: A Review of Available and Future Technology for Monitoring Treaty Compliance, Workshop Report, Ann Arbor, MI, USA, 20–22 October 1999, 2000a, 159 pp. Available at http://www.eecs.umich.edu/kyoto]. The implications of significant decisions pertaining to the definition of the key terms forest and afforestation, reforestation and deforestation (ARD) activities taken at the conference of parties (COP 6:2 and COP 7) meetings in Bonn and Marrakesh, respectively in 2001 are also discussed. Past, current and near-future remote sensing instruments with applications appropriate to Kyoto requirements are short listed; research topics that need to be advanced to support use of these are outlined, and future actions recommended.

A comprehensive archaeological map of the world's largest preindustrial settlement complex at Angkor, Cambodia

The great medieval settlement of Angkor in Cambodia [9th–16th centuries Common Era (CE)] has for many years been understood as a “hydraulic city,” an urban complex defined, sustained, and ultimately overwhelmed by a complex water management network. Since the 1980s that view has been disputed, but the debate has remained unresolved because of insufficient data on the landscape beyond the great temples: the broader context of the monumental remains was only partially understood and had not been adequately mapped. Since the 1990s, French, Australian, and Cambodian teams have sought to address this empirical deficit through archaeological mapping projects by using traditional methods such as ground survey in conjunction with advanced radar remote-sensing applications in partnership with the National Aeronautics and Space Administration (NASA)/Jet Propulsion Laboratory (JPL). Here we present a major outcome of that research: a comprehensive archaeological map of greater Angkor, covering nearly 3,000 km2, prepared by the Greater Angkor Project (GAP). The map reveals a vast, low-density settlement landscape integrated by an elaborate water management network covering >1,000 km2, the most extensive urban complex of the preindustrial world. It is now clear that anthropogenic changes to the landscape were both extensive and substantial enough to have created grave challenges to the long-term viability of the settlement.

The effect of changing environmental conditions on microwave signatures of forest ecosystems: preliminary results of the March 1988 Alaskan aircraft SAR experiment

Abstract In preparation for the first European Space Agency (ESA) Remote Sensing(ERS-I) mission,a series of multitemporal, multifrequency, multipolarization aircraft synthetic aperture radar (SAR) data sets were acquired over the Bonanza Creek Experimental Forest near Fairbanks, Alaska in March, 1988. P-, L- and C-band data were acquired with the NASA/JPL Airborne SAR on five differentdays over a period of two weeks. The airborne data were augmented with intensiveground calibration data as well as detailed, simultaneous in situ measurements of the geometric, dielectric and moisture properties of the snow and forest canopy. During the time period over which the SAR data were collected, the environmental conditions changed significantly; temperatures ranged from unseasonably warm (I to 9°C) to well below freezing (-8 to - 15°C), and the moisture content of the snow and trees changed from a liquid to a frozenstate. The SAR data clearly indicate the radar return is sensitive to these changing environmental fa...

Remotely sensed indicators of habitat heterogeneity: use of synthetic aperture radar in mapping vegetation structure and bird habitat

An integrated remote sensing/field ecology project linked the use of synthetic aperture radar (SAR) and aerial photography to studies of landscape spatial heterogeneity and bird community ecology. P-, L-, and C-band SAR data, collected over a section of Kakadu National Park in Australias Northern Territory during the Joint NASA/Australia DC-8 data acquisition campaign, were analyzed in light of field data integrating vegetation structure and floristics with bird abundances across a heterogeneous study site. Results indicate that SAR data are able to discern structural differences relevant to bird habitat quality within floristically homogeneous stands, while multispectral sensors successfully identified floristic differences among habitat types. Simplifying indices of bird diversity showed ambiguous changes across the site; however, the abundances of individual species were observed to change significantly across both floristic and structural gradients. These results suggest that efforts to map bird diversity should focus on species-specific habitat relationships and that some measure of vegetation structure is needed to understand bird habitat. The approach employed here advances the use of SAR data in the three-dimensional mapping of animal habitats from remotely sensed data, and extends current capabilities for mapping and modeling large-scale patterns in the distribution of biological diversity.

Segmentation and classification of vegetated areas using polarimetric SAR image data

Classification of radar images based on the information provided by individual pixels cannot generally produce satisfactory results due to speckle. The classification based on area analysis is therefore expected to be more accurate, as a uniform area, which usually consists of multipixels, provides reliable measurement statistics and texture characteristics. However, the area analysis requires partitions of uniform areas to be performed first. In this paper, an approach to the classification of radar images is developed based on two steps. First an image is partitioned into uniform areas (segments), and then these segments are classified. Both segmentation and classification are achieved by using the Gaussian Markov random field model. Test images are classified to demonstrate the method.

Use of stereo aerial photography for quantifying changes in the extent and height of mangroves in tropical Australia

The study investigated the use of aerial photographs, acquired in 1950 and1991, for assessing the temporal dynamics of mangroves along the WestAlligator River in Australias Northern Territory. For both years,mangrove extent was mapped using an unsupervised classification of thedigital orthomosaic and Digital Elevation Models (DEMs), or height maps,of the mangrove canopy were derived from stereo pairs. Helicopter andfield observations in 1998 and 1999 respectively provided ground truthfor interpreting the derived datasets. The comparison of mangrove extentrevealed a substantial movement over the 41-year period, perhaps inresponse to hydrological changes that have resulted in a landward extensionof saline conditions. Changes in the height of mangroves were observedbut were difficult to quantify due to the reduced quality of the 1950 DEM. The study demonstrated the viability of using time-series of aerialphotography for monitoring and understanding the long-term response ofmangroves to environmental change, including hydrological variations andsea level rise.

The use of remote sensing in mapping and monitoring vegetational change associated with bushfire events in Eastern Australia

The value of Landsat data for spatial analysis in land cover studies is well known. Potentially as valuable is its use in forecasting and monitoring temporal land cover changes such as those associ...

Comparison of radar image segmentation by Gaussian- and Gamma-Markov random field models

This paper compares segmentation results of synthetic aperture radar (SAR) images using Gaussian-Markov random field (MRF) and Gamma-MRF models. A Gamma distribution function is more accurate and proper to trace the multilook SAR intensity data distribution. However, it is found that, at least from examples used in the paper, when the distribution function is incorporated with the MRF model to implement SAR image segmentation, the Gamma-MRF model is not necessarily shown to be superior to the Gaussian-MRF model. Occasionally the Gamma-MRF model wrongly merges a few small segments, suggesting that the Gaussian-MRF model might be more stable and reliable.

Systematic data acquisitions-a prerequisite for meaningful biophysical parameter retrieval?

Implementation of systematic Earth observation data acquisition plans over extensive regions, in which the spatial and temporal components of relevant ground targets are adequately taken into account, is a prerequisite for successful retrieval of bio- and geophysical parameters and imperative to accommodate extrapolation of locally developed models to regional scales as required in the context of terrestrial carbon cycle science. Straightforward in concept, but surprisingly uncommon in mission operations thus far, the key characteristics of such a systematic data acquisition strategy are outlined in this short communication.

A review of SAR speckle filters: texture restoration and preservation

Speckle filtering is probably one of the important steps in post SAR (synthetic aperture radar) image processing. Speckle appears in all SAR products including single-polarimetric, multipolarimetric and interferometric image data. Many speckle filtering algorithms have been proposed aimed at speckle reduction. Texture, revealing the spatial-dependent information in images, may be as important as other polarimetric measures. Such information is not expected being distorted and degraded during speckle suppression. This paper examines various speckle filters including the Lee, Frost, Kuan and other filters in terms of texture preservation. The first and second order texture measures are used in the assessment.