Airborne remote sensing measurements provide the capability to quantitatively measure biochemical and biophysical
properties of vegetation at regional scales, therefore complementing surface and satellite measurements. The National
Ecological Observatory Network (NEON) will build three airborne systems to allow for routine coverage of NEON sites
(60 sites nationally) and the capacity to respond to investigator requests for specific projects. Each airborne system will
consist of an imaging spectrometer, waveform lidar and high-resolution digital camera. Remote sensing data gathered
with this instrumentation needs to be quantitative and accurate in order to derive meaningful information about
ecosystem properties and processes. Also, comprehensive and long-term ecological studies require these data to be
comparable over time, between coexisting sensors and between generations of follow-on sensors. NEON's calibration
plan for the airborne instrument suite relies on intensive laboratory, on-board, ground-based characterization as well as
inter-sensor comparisons. As part of these efforts, NEON organized a pathfinder mission in September 2010 to test
prototype techniques and procedures for field sampling and sensor validation. Imaging spectroscopy data from AVIRIS
and waveform lidar data were acquired in addition to ecological field sampling at the Ordway-Swisher Biological
Station near Gainesville, Florida. This paper presents NEON's capabilities for validation of at-sensor radiance of
airborne and space-based sensors and shows results from the September 2010 pathfinder mission.
The National Ecological Observatory Network (NEON) will be the first observatory network of its kind designed to
detect and enable forecasting of ecological change at continental scales over multiple decades. NEON will collect data at
sites distributed at 20 ecoclimatic domains across the United States on the impacts of climate change, land use change,
and invasive species on natural resources and biodiversity. The NEON Airborne Observation Platform (AOP) is an
aircraft platform carrying remote sensing instrumentation designed to achieve sub-meter to meter scale ground
resolution, bridging the scales from organisms and individual stands to satellite-based remote sensing. AOP
instrumentation consists of a VIS/SWIR imaging spectrometer, a scanning small-footprint waveform LiDAR, and a high
resolution airborne digital camera. AOP data will provide quantitative information on land use change and changes in
ecological structure and chemistry including the presence and effects of invasive species. A Pathfinder Flight Campaign
was conducted over a two week period during late August to early September 2010 in order to collect representative
AOP data over one NEON domain site. NASA JPL flew the AVIRIS imaging spectrometer and NCALM flew an Optech
Gemini waveform LiDAR over the University of Florida Ordway-Swisher Biological Station and Donaldson tree
plantation near Gainesville Florida. The pathfinder data are discussed in detail along with how the data are being used
for early algorithm and product development prototyping activities. The data collected during the campaign and
prototype products are openly available to scientists to become more familiar with representative NEON AOP data.
Airborne remote sensing provides the opportunity to quantitatively measure biochemical and biophysical properties of
vegetation at regional scales, therefore complementing surface and satellite measurements. Next-generation programs
are poised to advance ecological research and monitoring in the United States, the tropical regions of the globe, and to
support future satellite missions. The Carnegie Institution will integrate a next generation imaging spectrometer with a
waveform LiDAR into the Airborne Taxonomic Mapping System (AToMS) to identify the chemical, structural and
taxonomic makeup of tropical forests at an unprecedented scale and detail. The NEON Airborne Observation Platform
(AOP) is under development with similar technologies with a goal to provide long-term measurements of ecosystems
across North America. The NASA Next Generation Airborne Visible/Infrared Imaging Spectrometer (AVIRISng) is also
under development to address the science measurement requirements for both the NASA Earth Science Research and
Analysis Program and the spaceborne NASA HyspIRI Mission. Carnegie AToMS, NEON AOP, and AVIRISng are
being built by the Jet Propulsion Laboratory as a suite of instruments. We discuss the synergy between these programs
and anticipated benefits to ecologists and decision-makers.
Airborne remote sensing plays a critical role in the scaling strategy underpinning the National Ecological Observatory
Network (NEON) design. Airborne spectroscopy and waveform LiDAR will quantify plant species type and function,
and vegetation structure and heterogeneity at the scale of individual shrubs and larger plants (1-3 meters) over hundreds
of square kilometers. Panchromatic photography at better than 30 cm resolution will retrieve fine-scale information
regarding land use, roads, impervious surfaces, and built structures. NEON will build three airborne systems to allow
for routine coverage of NEON sites (60 sites nationally) and the capacity to respond to investigator requests for specific
projects. The system design achieves a balance between performance, and development cost and risk. The approach
takes full advantage of existing commercial airborne LiDAR and camera components. However, requirements for the
spectrometer represent a significant advancement in technology. A pushbroom imaging spectrometer design is being
proposed to simultaneously achieve high spatial, spectral and signal-to-noise ratio and a high degree of uniformity in
response across wavelength and a wide field of view. To reduce risk during NEON construction, a spectrometer design
verification unit is under development by the Jet Propulsion Laboratory to demonstrate that the design and component
technologies meet operational and performance requirements. This paper presents an overview of system design, key
requirements and development status of the NEON airborne instrumentation.
The National Ecological Observatory Network (NEON) is an ecological observation platform for discovering, understanding and forecasting the impacts of climate change, land use change, and invasive species on continental-scale ecology. NEON will operate for 30 years and gather long-term data on ecological response changes and on feedbacks with the geosphere, hydrosphere, and atmosphere. Local ecological measurements at sites distributed within 20 ecoclimatic domains across the contiguous United States, Alaska, Hawaii, and Puerto Rico will be coordinated with high resolution, regional airborne remote sensing observations. The Airborne Observation Platform (AOP) is an aircraft platform carrying remote sensing instrumentation designed to achieve sub-meter to meter scale ground resolution, bridging scales from organisms and individual stands to satellite-based remote sensing. AOP instrumentation consists of a VIS/SWIR imaging spectrometer, a scanning small-footprint waveform LiDAR for 3-D canopy structure measurements and a high resolution airborne digital camera. AOP data will be openly available to scientists and will provide quantitative information on land use change and changes in ecological structure and chemistry including the presence and effects of invasive species. AOP science objectives, key mission requirements, and development status are presented including an overview of near-term risk-reduction and prototyping activities.
The National Ecological Observatory Network (NEON), being funded by the National Science Foundation, is a
continental-scale research platform for discovering, understanding and forecasting the impacts of climate change, land-use
change, and invasive species on ecology. Local site-based flux tower and field measurements will be coordinated
with high resolution, regional airborne remote sensing observations. The NEON Airborne Observation Platform (AOP)
consists of an aircraft platform carrying remote sensing instrumentation designed to achieve sub-meter to meter scale
ground resolution to bridge scales from organism and stand scales to the scale of satellite based remote sensing. Data
from the AOP will be openly available to the science community and will provide quantitative information on land use
change, and changes in ecological structure and chemistry including the presence and effects of invasive species.
Remote sensing instrumentation consists of an imaging spectrometer measuring surface reflectance over the continuous
wavelength range from 400 to 2500 nm with 10 nm resolution, a scanning, small footprint waveform LiDAR for 3-D
canopy structure measurements and a high resolution airborne digital camera. The AOP science objectives, key mission
requirements, the conceptual design and development status are presented.
A new heliostat facility at Ball Aerospace and Technologies Corporation (BATC) in Boulder, CO will allow the use of
the sun as the source in the calibration of earth observing sensors. The solar spectrum is the basic energy source for such
instruments; therefore it is advantageous to perform initial ground radiometric calibrations using the sun. Using this
method for preflight radiometric calibration reduces uncertainties caused by the spectral mismatch between the preflight
and in-flight calibration, especially in the case in which a solar diffuser is the in-flight calibration method. This method
also reduces stray light concerns as the instrument diffuser is measured in situ with the same radiance level it sees on
orbit. This paper presents the design of a heliostat test facility which tracks the sun and directs the solar beam into a
thermal vacuum chamber, allowing the instrument under test to be kept in a safe, clean and controllable environment.
Design considerations that affect the uniformity and transmission of the system are discussed. The opto-mechanical
logistics of creating a heliostat that will deliver a 13-inch solar beam into a thermal vacuum chamber are also presented.
This facility is currently under construction at BATC and is expected to be operational by the end of 2008.
The Remote Sensing Group (RSG) at the University of Arizona has performed high-accuracy radiometric calibration in
the laboratory for more than 20 years in support of vicarious calibration of space-borne and airborne imaging sensors.
Typical laboratory calibration relies on lamp-based sources which, while convenient to operate and control, do not
simulate the solar spectrum that is the basic energy source for many of the imaging systems. Using the sun as a source
for preflight radiometric calibration reduces uncertainties caused by the spectral mismatch between the preflight and
inflight calibration, especially in the case in which a solar diffuser is the inflight calibration method. Difficulties in using
the sun include varying atmospheric conditions, changing solar angle during the day and with season, and ensuring
traceability to national standards. This paper presents several approaches using the sun as a radiometric calibration
source coupled with the expected traceable accuracies for each method. The methods include direct viewing of the solar
disk with the sensor of interest, illumination of the sensor's inflight solar diffuser by the sun, and illumination of an
external diffuser that is imaged by the sensor. The results of the error analysis show that it is feasible to achieve preflight
calibration using the sun as a source at the same level of uncertainty as those of lamp-based approaches. The error
analysis is evaluated and compared to solar-radiation-based calibrations of one of RSG's laboratory-grade radiometers.
The Airborne Sensors Initiative (ASI) at Ball Aerospace and Technologies Corp. (BATC) specializes in airborne
demonstration of internally-developed instrument concepts and innovative remote sensing technologies. In December
2006, ASI flew an environmental remote sensing suite consisting of the Low Light Imager (LLI) and Prototype Airborne
Visible Imaging Spectrometer (PAVIS), both of which are operated using a pushbroom approach. LLI is designed for
nighttime or high dynamic range imaging. It is capable of yielding 107 dynamic range and offers quality images amid
illumination extending from a 1/4 moon to full sunlight and with autonomous operation. PAVIS is an imaging
spectrometer based on the Dyson design and exhibits a 200 nm spectral bandwidth tunable within 400 − 850 nm.
Developed internally to demonstrate promising remote sensing capabilities, these small, low-mass and low-power
instruments are prepared for aircraft flight and are currently being used in the field to acquire scientific data. The
LLI/PAVIS instrument suite has been utilized to collect airborne urban and rural imagery, as well as spectral information
about the Great Salt Lake area, western Colorado, and ancient lava flows in southern Idaho. Highlights of the instrument
design and ensuing data from previous flights are presented herein.
The Landsat series of sensors have supplied the remote sensing community with a continuous data set dating to the early 1970s. An important aspect of retaining the continuity of these data is that a Landsat follow-on as well as current Landsat instruments must be understood radiometrically throughout their mission. The Advanced Land Imager (ALI), for example, was developed as a prototype for the next generation of Landsat Instruments, and as such there was a significant effort to understand its radiometric characteristics as well as how it compares with previous Landsat sensors. The Remote Sensing Group at the University of Arizona has been part of this effort since the late 2000 launch of ALI through the use of the reflectance-based method of vicarious calibration. The reflectance-based approach consists of ground-based measurements of atmospheric conditions and surface reflectance at the time of satellite overpass to predict the at-sensor radiance seen by the sensor under study. The work compares results from the reflectance-based approach obtained from well-characterized test sites such as Railroad Valley Playa in Nevada and Ivanpah Playa in California as applied to ALI, Landsat-5 TM, and Landsat-7 EMT+. The results from the comparison use a total of 14 ALI dates spanning in time from 2001 to late 2005 and show that ALI agrees with the current radiometric results from TM and ETM+ to within 5%.
An imaging polarimeter for sensing of aerosol scattering and other atmospheric phenomena has been constructed and tested. The instrument is a testbed for a multispectral system architecture, in which spectral channels are added in a modular fashion using dichroic beamspltters and dedicated detectors. The testbed operates in a pushbroom scanning mode, with two co-boresighted optical trains. Each optical train features a narrow-band filter, an intermediate image at a slit, collimating optics, an appropriately oriented Wollaston prism, and two linear detector arrays. Consequently, the testbed is capable of determining the first three Stoke components (linear polarization) at a single wavelength. We describe calibration and field testing and present preliminary data analysis results.
Airborne radiometric instruments are often used to collect radiance data, whether for producing remote sensing imagery, for use in vicarious calibration, or for atmospheric correction. Reflected radiance from a test site is detected by an Exotech model 100BX radiometer that contains four different spectral filters which coincide with the first four bands of Landsat Thematic Mapper (TM). These filters can be interchanged with filters that correspond to the first three multispectral bands of SPOT. Typically these radiometers are calibrated in a laboratory environment with incandescent radiance sources whose spectral outputs are known by some established standard. In the field, the radiometers are used with a different source than that used for the laboratory calibration, namely the sun. The solar radiation based calibration (SRBC) has been demonstrated to be an accurate calibration method for these instruments. The major advantage of this method is that the source for the calibration is the same source used in acquiring field measurements. In this work, solar radiation based calibration is compared to laboratory radiometric calibration done with a spherical integrating source (SIS) and a lamp source in the Remote Sensing Group (RSG) blacklab for airborne radiometers. Results of measurements taken over Ivanpah Playa on 6 July 2000 and 4 June 2000 by an Exotech model 100BX calibrated with these methods are presented and biases in the three different calibration methods are discussed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.