the types of operations, their output products and associated validation needs as a
basis for understanding the application and management chapters. Image processing operations are applied once the geometric, radiometric and atmospheric
correction operations are complete.
Two general types of processing operations can be applied, with the distinction
based on the type of output map required for science or management purposes. In
this context, all of the processing and output data are in digital format and can be
referred to as digital maps or spatial information.
Processing to thematic maps: In this processing option, a variety of techniques,
ranging from manual to automated, are used to group pixels representing the same
feature on a coral reef into pre-defined sets of thematic classes. The output is an
imaged-based map of the different classes as defined for a given level of detail,
such as geomorphic zones or benthic communities (e.g., Ahmad and Neil 1994;
Andréfouët et al. 2003; Andréfouët et al. 2005a). These maps are often referred to
as categorical or thematic, and show discrete boundaries.
Processing to biophysical property maps: In this processing option, either
empirical relationships or established models are applied to each image pixel to
produce an estimate of a biophysical property. Examples include bathymetry or
chlorophyll-a concentration in the water column (e.g., Purkis et al. 2002; Mumby
et al. 2004a; Kutser and Jupp 2006; Kutser et al. 2006). These are often referred to
as continuous maps since each pixel has a unique value.
In each approach there is also capacity to include other forms of remote sensing
imagery and spatial data (e.g., boat–based sonar, airborne LiDAR depth sounding,
or pre-existing maps) to improve map accuracy or expand the types of features or
processes able to be mapped (Brock and Purkis 2009; Bejarano et al. 2010). Each
of the output map products can also be used to produce maps for the same area
over time and then used in the detection and measurement of changes or trends in
coral reef properties and associated processes over time (Palandro et al. 2003,
2008; Scopelitis et al. 2007, 2009; Chap. 15).
1.3.3 Thematic Mapping
Thematic maps can be produced using two general approaches: manual digitizing
of boundaries of an image or photo displayed on the screen using a pre-set list of
classes and interpretation cues; or utilizing mapping algorithms provided in imageprocessing software. The choice of which method to use depends on: the output
coral reef map classes required; the type of photograph or image data being used;
amount of background knowledge and experience of the person(s) doing the
mapping; and availability of field data for the area to be mapped. A more detailed
outline of this process and its options is provided in the Remote Sensing Toolkit
(www.gpem.uq.edu.au/cser-rstoolkit).
Manual digitizing can be applied to all forms of photography, multispectral and
hyperspectral images, but has most frequently been used in higher spatial
20
S. R. Phinn et al.
basis for understanding the application and management chapters. Image processing operations are applied once the geometric, radiometric and atmospheric
correction operations are complete.
Two general types of processing operations can be applied, with the distinction
based on the type of output map required for science or management purposes. In
this context, all of the processing and output data are in digital format and can be
referred to as digital maps or spatial information.
Processing to thematic maps: In this processing option, a variety of techniques,
ranging from manual to automated, are used to group pixels representing the same
feature on a coral reef into pre-defined sets of thematic classes. The output is an
imaged-based map of the different classes as defined for a given level of detail,
such as geomorphic zones or benthic communities (e.g., Ahmad and Neil 1994;
Andréfouët et al. 2003; Andréfouët et al. 2005a). These maps are often referred to
as categorical or thematic, and show discrete boundaries.
Processing to biophysical property maps: In this processing option, either
empirical relationships or established models are applied to each image pixel to
produce an estimate of a biophysical property. Examples include bathymetry or
chlorophyll-a concentration in the water column (e.g., Purkis et al. 2002; Mumby
et al. 2004a; Kutser and Jupp 2006; Kutser et al. 2006). These are often referred to
as continuous maps since each pixel has a unique value.
In each approach there is also capacity to include other forms of remote sensing
imagery and spatial data (e.g., boat–based sonar, airborne LiDAR depth sounding,
or pre-existing maps) to improve map accuracy or expand the types of features or
processes able to be mapped (Brock and Purkis 2009; Bejarano et al. 2010). Each
of the output map products can also be used to produce maps for the same area
over time and then used in the detection and measurement of changes or trends in
coral reef properties and associated processes over time (Palandro et al. 2003,
2008; Scopelitis et al. 2007, 2009; Chap. 15).
1.3.3 Thematic Mapping
Thematic maps can be produced using two general approaches: manual digitizing
of boundaries of an image or photo displayed on the screen using a pre-set list of
classes and interpretation cues; or utilizing mapping algorithms provided in imageprocessing software. The choice of which method to use depends on: the output
coral reef map classes required; the type of photograph or image data being used;
amount of background knowledge and experience of the person(s) doing the
mapping; and availability of field data for the area to be mapped. A more detailed
outline of this process and its options is provided in the Remote Sensing Toolkit
(www.gpem.uq.edu.au/cser-rstoolkit).
Manual digitizing can be applied to all forms of photography, multispectral and
hyperspectral images, but has most frequently been used in higher spatial
20
S. R. Phinn et al.