100
be noted that in some environments (e.g., the southern Mediterranean), the pre- and
peak-flush periods may be associated with summer and winter whereas in northern
Europe, this is reversed.
For this project, a Worldview-2 image was captured at peak (July 2012) and post
flush (September 2012). Unfortunately, satellite imagery is not provided as readyto- use data and a set of processing steps needs to be undertaken before any further
analysis such as classification. Several factors can affect satellite measurements,
from variations in atmospheric conditions to viewing geometry, and these effects
need to be corrected to ensure comparability of different images and sensors within
and between years. The main corrections applied to imagery are atmospheric, radiometric and orthorectification and have been reviewed in Chap. 3.
LiDAR
Light Detection and Ranging (LiDAR) data is often used (for) to create VHR Digital
Terrain Models (DTMs) and Digital Surface Models (DSMs). In the UK, the
Environment Agency Geomatics Group routinely collects airborne LiDAR data
from coastlines and catchments in England and Wales to generate DTMs and derived
products at 1–2 m spatial resolution. As of September 2015, processed Digital
Terrain and Surface Models and point cloud 3D datasets are freely available to anyone under a governmental open-data scheme in the UK. (Available from Data.gov.
uk). For this project, products such as slope and aspect were also calculated from
this dataset in addition to the DTM.
Data from Unmanned Aerial Vehicles (UAVs) and Aerial Photography
Recent advances in UAV technologies and software have facilitated routine and
exponential use of these data for environmental applications. However, for habitat
monitoring, data needs to be flown at consistent heights under optimal conditions
for comparability. For this reason, users need to consider their options carefully and
plan flights in a manner that aids the processing of data after acquisitions (e.g., by
placing light and dark tarpaulins on sites that are sufficiently large to capture atmospheric conditions for correction, which might not be suitable for small protected
sites). The UAV data used for this project were acquired at low cost over multiple
days and were mosaicked and georeferenced subsequently to create a visual single
snapshot product at 40 cm pixel resolution.
Aerial photography is still extensively used by nature conservation bodies in the
UK. The images are typically acquired every 5 years, in the red, green and blue
channels with a pixel resolution of <1 m, depending on flight altitude. Data acquired
in the NIR channels are also becoming more popular but processing usually involves
mosaicking of different flight paths and colour rendering and matching to remove
variability within the imagery as, during national acquisitions, data are captured on
different days. These images, therefore, are not calibrated and cannot be used to
G. Jones et al.
be noted that in some environments (e.g., the southern Mediterranean), the pre- and
peak-flush periods may be associated with summer and winter whereas in northern
Europe, this is reversed.
For this project, a Worldview-2 image was captured at peak (July 2012) and post
flush (September 2012). Unfortunately, satellite imagery is not provided as readyto- use data and a set of processing steps needs to be undertaken before any further
analysis such as classification. Several factors can affect satellite measurements,
from variations in atmospheric conditions to viewing geometry, and these effects
need to be corrected to ensure comparability of different images and sensors within
and between years. The main corrections applied to imagery are atmospheric, radiometric and orthorectification and have been reviewed in Chap. 3.
LiDAR
Light Detection and Ranging (LiDAR) data is often used (for) to create VHR Digital
Terrain Models (DTMs) and Digital Surface Models (DSMs). In the UK, the
Environment Agency Geomatics Group routinely collects airborne LiDAR data
from coastlines and catchments in England and Wales to generate DTMs and derived
products at 1–2 m spatial resolution. As of September 2015, processed Digital
Terrain and Surface Models and point cloud 3D datasets are freely available to anyone under a governmental open-data scheme in the UK. (Available from Data.gov.
uk). For this project, products such as slope and aspect were also calculated from
this dataset in addition to the DTM.
Data from Unmanned Aerial Vehicles (UAVs) and Aerial Photography
Recent advances in UAV technologies and software have facilitated routine and
exponential use of these data for environmental applications. However, for habitat
monitoring, data needs to be flown at consistent heights under optimal conditions
for comparability. For this reason, users need to consider their options carefully and
plan flights in a manner that aids the processing of data after acquisitions (e.g., by
placing light and dark tarpaulins on sites that are sufficiently large to capture atmospheric conditions for correction, which might not be suitable for small protected
sites). The UAV data used for this project were acquired at low cost over multiple
days and were mosaicked and georeferenced subsequently to create a visual single
snapshot product at 40 cm pixel resolution.
Aerial photography is still extensively used by nature conservation bodies in the
UK. The images are typically acquired every 5 years, in the red, green and blue
channels with a pixel resolution of <1 m, depending on flight altitude. Data acquired
in the NIR channels are also becoming more popular but processing usually involves
mosaicking of different flight paths and colour rendering and matching to remove
variability within the imagery as, during national acquisitions, data are captured on
different days. These images, therefore, are not calibrated and cannot be used to
G. Jones et al.