Proceedings of the Symposium on Global and Environmental Monitoring: Proceedings of the Symposium on Global and Environmental Monitoring

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Persistent identifier:: 856665355

Title:: Proceedings of the Symposium on Global and Environmental Monitoring

Sub title:: techniques and impacts ; September 17 - 21, 1990, Victoria Conference Centre, Victoria, British Columbia, Canada

Year of publication:: 1990

Place of publication:: Victoria, BC

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 856665355

Language:: English

Document type:: Multivolume work

Volume

Persistent identifier:: 856669164

Title:: Proceedings of the Symposium on Global and Environmental Monitoring

Sub title:: techniques and impacts; September 17 - 21, 1990, Victoria Conference Centre, Victoria, British Columbia, Canada

Scope:: XIV, 912 Seiten

Year of publication:: 1990

Place of publication:: Victoria, BC

Publisher of the original:: [Verlag nicht ermittelbar]

Identifier (digital):: 856669164

Illustration:: Illustrationen, Diagramme, Karten

Signature of the source:: ZS 312(28,7,1)

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: International Society for Photogrammetry and Remote Sensing, Commission of Photographic and Remote Sensing Data

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: [WP-3 FOREST INVENTORY APPLICATIONS]

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: EVALUATING AIRBORNE LINEAR ARRAY TECHNOLOGY FOR OPERATIONAL FOREST INVENTORY APPLICATIONS IN BRITISH COLUMBIA. Paul G. Pilon

Document type:: Multivolume work

Structure type:: Chapter

387 selected, the width and positioning of each band being selectable by software. 2.4 Radiometric Resolution The pushbroom principle of linear array imagers offers greatly improved radiometric responsitivity, compared to optical-mechanical scanners. High radiometric sensitivity and dynamic range allow small changes in features to be observed. The dynamic range for all of the channels of the MEIS II sensor, for example, is better than 4500:1, and close to 7000:1 for four of the channels (Till et al., 1987). The FLI and CASI systems have dynamic ranges better than 4000:1 (Borstad et al., 1989). This higher sensitivity to spectral intensity with airborne linear array sensors is the result of the incorporation of multiple detectors in an array, of which each is able to integrate over one pixel for the whole scan line. The integration period or each pixel is approximately 3000 times longer than optical-mechanical scanners allowing smaller radiances to be measured due to improved noise equivalent radiance (McColl et al, 1983). This higher spectral sensitivity provided signal-to-noise ratios greater than 100:1 over forested terrains using the MEIS II system (Till et al., 1986a). 2.5 Geometric Performance The superior geometric quality of the output imagery from linear array systems, when compared to equivalent optical-mechanical imagery, allow such data to be more easily integrated with geo-referenced computer-based inventories. The MEIS airborne system, for example, provides inter channel pixel registration to within 0.15 pixel, over the complete range of aircraft altitudes. For applications relating to cartography or multitemporal registration, additional processing of the data is required to correct for other changes in aircraft motion such as changes in velocity, pitch and yaw, etc. A processing system has been developed to correct MEIS imagery using flight navigation data. Based on algorithms developed by Gibson (1984), aircraft inertial navigation data are used to compute positions for all input pixels and to resample the imagery to a user selectable geo-referenced output grid. Geo-coded imagery has been produced from FLI imagery using Moniteq’s AIR-2 software and flight parameters recorded simultaneously with the imagery. Approximately one pixel precision has been achieved with spatial mode data (Buxton, 1988). 2.6 Stereo Capability In addition to the nadir-mode of operation, the MEIS system can be used to acquire continuous fore-aft stereo imagery, by using the precision stereo mirror module. In the stereo mode, two of the eight channels look fore and aft at angles of +/-35° while six channels look nadir. The data may be combined with aircraft altitude data to provide digital terrain information and standard geometrically corrected products. Fore-aft stereo acquisition may also be able to provide information appropriate for forest stand height determination. With geometric correction capability stereo imagery is also suitable for base mapping and topographic mapping. 2.7 Digital Format The digital format of airborne linear array imagery allows easier integration with digital databases such as geographic information systems and lends itself to automated processing of the imagery. In a digital form the imagery can also be more easily enhanced to improve visual interpretation. Digital imagery can also be easily mosaicked to provide large area coverage or ortho photos. 3.0 CURRENT LINEAR ARRAY SYSTEMS The discussion of available linear array sensors will be restricted primarily to systems developed in Canada which have application to forestry. The discussion will not include systems developed for monitoring the atmosphere or systems developed primarily for ground based use (e.g., non-imaging spectrometers or radiometers). 3.1 MEIS History and Description The MEIS (Multispectral Electro-Optical Imaging Sensor) is an airborne linear array sensor system developed for the Canada Centre for Remote Sensing (CCRS). The MEIS airborne multispectral imager was the first solid state linear array imager to be developed and provide data to the remote sensing community (Zwick et al, 1978). It was part of a multi-year Canadian research and development initiative to evaluate pushbroom imager technology and to develop applications. Development was started in the late 1970’s with the prototype, two channel, MEIS I sensor. The sensor had two optical channels each with a 512-element photodiode linear array. MEIS I was successfully operated in the laboratory and in the air, and provided a useful demonstration of the pushbroom imager concept. Results were significant enough to lead to the development of the current eight channel MEIS II. This version was developed under contract to CCRS by MacDonald, Dettwiler and Associates Ltd. of Vancouver, British Columbia. In the four year period from 1983 to 1986, close to two hundred missions were flown with MEIS II throughout Canada, USA and Australia (Till et al., 1986b).

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