must instead be considered (see Sects. 1.2 and 1.3). The second research path has
been development of higher-level products that provide insight to reef status or
function (Atkinson and Grigg 1984; Bour et al. 1986; Loubersac et al. 1988;
Mumby et al. 1997; Hochberg and Atkinson 2000, 2008; Roelfsema et al. 2002;
Isoun et al. 2003; Andréfouët et al. 2004a; Lesser and Mobley 2007; Palandro et al.
2008; Purkis et al. 2008). A number of basic products produced from this research
are currently in routine use, while others remain in development.
Chapters 2– 4 cover the most commonly available, and frequently used, sources
of passive visible and infrared remote sensing data, including film based aerial and
space photography, digital cameras, and multispectral and hyperspectral imaging
systems. The progression through these technologies also represents a progression
in detail of coral reef information that can be retrieved from the respective data
sources. Generally, the detail in information content is controlled by the spatial
and spectral capabilities of the sensor. A main focus of this chapter is describing
the control that spatial resolution and spectral band number, band width and band
position have on the information able to be mapped.
Aerial photography is the simplest and most historically relevant data set,
typically covering local to regional scales (several km
2 to 100s of km
2 ), sometimes
with records stretching back to the 1930s (Hernandez-Cruz et al. 2006). Astronaut
photography is also available, and although collection is opportunistic rather than
systematic, valuable information can be extracted from this imagery. Recent
advances in aerial photography have also seen large format digital cameras being
adopted and used extensively by survey companies and governments. These systems provide larger area coverage, less processing and more consistent spectral
data than previous generations of cameras. Multispectral systems generally cover
the same tasks as aerial photography, but over larger areas (10
4 –10
6 km
2 ), with
significant repeat capacity. Hyperspectral sensors provide added spectral bands,
with much narrower bandwidths and greater ability to identify specific targets.
1.1.2 Chapter Outline
This chapter provides the technical basis for understanding Chaps 2–4, and an
overview of the situations in which passive visible and infrared remote sensing
does and doesn’t work for mapping and monitoring coral reefs. The chapter starts
by explaining the spectral dimensions of remote sensing instruments in detail,
along with how these dimensions control the amount and type of information on
coral reefs that can be effectively mapped. A specific set of biophysical environmental variables, relevant to coral reef science and management, and able to be
mapped by multispectral and hyperspectral systems, are then defined. Examples
are provided of image based map products and processing approaches required to
deliver science and management data for monitoring coral reefs. The chapter
finishes with an overview of future directions.
1 Visible and Infrared Overview
9
been development of higher-level products that provide insight to reef status or
function (Atkinson and Grigg 1984; Bour et al. 1986; Loubersac et al. 1988;
Mumby et al. 1997; Hochberg and Atkinson 2000, 2008; Roelfsema et al. 2002;
Isoun et al. 2003; Andréfouët et al. 2004a; Lesser and Mobley 2007; Palandro et al.
2008; Purkis et al. 2008). A number of basic products produced from this research
are currently in routine use, while others remain in development.
Chapters 2– 4 cover the most commonly available, and frequently used, sources
of passive visible and infrared remote sensing data, including film based aerial and
space photography, digital cameras, and multispectral and hyperspectral imaging
systems. The progression through these technologies also represents a progression
in detail of coral reef information that can be retrieved from the respective data
sources. Generally, the detail in information content is controlled by the spatial
and spectral capabilities of the sensor. A main focus of this chapter is describing
the control that spatial resolution and spectral band number, band width and band
position have on the information able to be mapped.
Aerial photography is the simplest and most historically relevant data set,
typically covering local to regional scales (several km
2 to 100s of km
2 ), sometimes
with records stretching back to the 1930s (Hernandez-Cruz et al. 2006). Astronaut
photography is also available, and although collection is opportunistic rather than
systematic, valuable information can be extracted from this imagery. Recent
advances in aerial photography have also seen large format digital cameras being
adopted and used extensively by survey companies and governments. These systems provide larger area coverage, less processing and more consistent spectral
data than previous generations of cameras. Multispectral systems generally cover
the same tasks as aerial photography, but over larger areas (10
4 –10
6 km
2 ), with
significant repeat capacity. Hyperspectral sensors provide added spectral bands,
with much narrower bandwidths and greater ability to identify specific targets.
1.1.2 Chapter Outline
This chapter provides the technical basis for understanding Chaps 2–4, and an
overview of the situations in which passive visible and infrared remote sensing
does and doesn’t work for mapping and monitoring coral reefs. The chapter starts
by explaining the spectral dimensions of remote sensing instruments in detail,
along with how these dimensions control the amount and type of information on
coral reefs that can be effectively mapped. A specific set of biophysical environmental variables, relevant to coral reef science and management, and able to be
mapped by multispectral and hyperspectral systems, are then defined. Examples
are provided of image based map products and processing approaches required to
deliver science and management data for monitoring coral reefs. The chapter
finishes with an overview of future directions.
1 Visible and Infrared Overview
9