DD296154A5 - ARRANGEMENT FOR OBTAINING REMOTE DATA - Google Patents

Abstract

The invention relates to the information and Mesztechnik in the optical field for the investigation of the Earth's surface of aerocosmic platforms. By means of the invention, it is possible to adaptively control the extraction of remote sensing data when using individual recording modules known per se taking into account different recording conditions and scene characteristics, to program thematically and to minimize the amount of data to be processed without limiting the content of the user information. The object of the invention is achieved by a Thematically Programmable Optoelectronic Multispectral Recording System (TOMAS), which has a panchromatic, geometrically high-resolution channel, multispectral channels in the visible and near infrared with high spectral and radiometric resolution and channels in the short-wave and thermal infrared. Furthermore, the recording arrangement contains a processor system connected to a database, a metorological sensor and a sensor for obtaining apron information and means known per se for visualizing the acquired image data in real time and memory modules. {Remote Sensing; multispectral; Recording system; User information, thematically programmable; Channel, panchromatic; Database; Processor system, geometrically high resolution; Control, adaptive}

Description

For this 2 pages drawings

Field of application of the invention

The invention relates to the information and measurement technology in the optical field for the investigation of the earth's surface of aerocosmic platforms. By means of the invention, it is possible to adaptively control the extraction of remote sensing data when using individual recording modules known per se taking into account different recording conditions and scene characteristics, to program thematically and to minimize the amount of data to be processed without restricting the content of the user information.

Characteristic of the known state of the art

Methods and devices for recording and evaluating multispectral remote sensing data / 1 /, methods for spectral analysis of multispectral data obtained with scanners / 2 / and methods for detecting objects on the earth's surface by comparing the spectral and structural features obtained by scanning are known be obtained with known, stored in the memory of an evaluation system data / 3 /.

Starting from the radiation flux of the electromagnetic radiation of the sun incident on the earth's surface after interaction with the atmosphere and the remission and emission properties of the different soil objects under different conditions and environmental influences, in / 1 / is an overview of the state of knowledge in the field of remote sensing in the optical field and the development of sensor technology. It turns out that due to the different spectral and geometric signature of the different objects under investigation (water, rocks, vegetation), very different demands have to be placed on the spectral band characteristics and the geometrical resolution of the remote sensing systems by the different geosciences. This results in the following tendencies:

- Extension of the spectral ranges of existing visible and near infrared (VNIR) multispectral recording systems with shortwave infrared (SWIR) and thermal infrared (TIR) channels - LANDSAT ™ (USA)

- Improvement of the geometrical and spectral resolution by transition from optical-mechanical to optoelectronic (line) scanning principle-MOMS (BRD), SPOT (France)

Development of imaging spectrometers with high spectral at lower spatial resolution using optoelectronic detector arrays and special optical systems AIS, AVIRIS (USA) and the possibility of programming the data acquisition - PMI (Canada), ROSIS (FRG)

U.S. Patent 3,829,218 discloses a method of spectral analysis for gross classification of soil objects by comparing the spectral signature of each scanner pixel with known spectral signatures stored in a database using an optical-mechanical multispectral scanner. In this solution, object recognition is very uncertain, because in the study of mixed pixels, the integral spectral signal can differ greatly from that of a homogeneous surface and thus vary the spectrograms very much.

According to DD-WP 160640, a method of spectral analysis for increasing the detection reliability by excluding spectroscopic object spectrograms from mixed spectra by evaluating structural data of the scanner pixels obtained with a high spatial resolution scanner and comparing the measured spectral and structural characteristics of each scanner pixel area with known, stored in the memory of an evaluation system data described. This should be able to increase the probability of secure object identification. The known technical solutions are only suitable for distinguishing certain object classes in the respectively observed scene. The technically unresolved problem is that the variance of the recording conditions (dynamic range, flight parameters, atmospheric parameters) in the known methods of

Remote sensing data acquisition no complex consideration. With known methods and arrangements of the programming of multispectral scanners, although specific data sets can be selected from a multiplicity of possible spectral channels of an imaging spectrometer. However, a thematic programming requires at least the consideration of variances of the recording conditions as well as a user-specific on-board data preprocessing.

For example, in the transition from one object class (vegetation) to another (body of water) during recording, the remission level may change to require switching the sensitivity range of the sensor system to obtain useful data. The same applies if the radiation conditions change during the recording (cloud cover).

1 Alexander F.H.Goetz, John B.Wellman, William L.Barnes

Optical Remote Sensing of the Earth PROCEEDINGS of the IEEE, Vol. 6 June 1985.

2 Edward J. Alyanak Method of Spectral Analysis US patent GOU 3/38 3,829,218.

3 G.A.Avanessov

Method of Spectral Analysis of Earth Surface Objects DD-WP G01 / J 3/38 160640.

4 MONITEQ PMI 3-85

Programmable Multispectral Imager (PMI).

Object of the invention

The object of the invention is to provide an arrangement for obtaining remote sensing data, wherein the recording of the image data depending on object features and specific user requirements can be selected thematically and a user-specific on-board preprocessing of the acquired image data is possible.

Explanation of the essence of the invention

Object of the invention is the development of an arrangement for obtaining remote sensing data using recording systems known per se for generating multi-spectral digital image data, wherein the recording of the image data depending on current object features and specific user requirements can be programmed thematically and simultaneously taking into account variations in the recording conditions on-board preprocessing of image data is possible.

The object of the invention is achieved by a Thematically Programmable Optoelectronic Multispectral Recording System (TOMAS), which has a panchromatic, geometrically high-resolution channel, multispectral channels in the visible and near infrared with high spectral and radiometric resolution and shortwave and thermal infrared channels , Furthermore, the recording arrangement contains a processor system connected to a database, a meteorological sensor and a sensor for obtaining apron information and means known per se for visualizing the acquired image data in real time as well as memory modules. Conveniently, the panchromatic channel is realized as a scanner or line scan camera. The respective instantaneous field of view (IFOV) of the multispectral channels is a whole multiple compared to the panchromatic channel in order to be able to assign a grid of panchromatic data to each multispectral pixel for the purpose of structural analysis (mixed pixel identification). The multispectral channels are expediently realized by an imaging spectrometer which contains line sensors in the focal plane of a dispersion optics.

With the arrangement according to the invention it becomes possible to distinguish the differences of radiometric (eg water / mainland), spectral (eg vegetation / soil) and geometric (eg texture of an orchard / geometry of a settlement) characteristics of different users of Remote sensing data to be examined objects to consider and recording of data in different sensitivity levels (radiometric adjustment), in different spectral channels (spectral adjustment) and possibly in high geometric resolution with a uniform, processor-assisted recording arrangement to allow. TOMAS realizes a thematic selection and preprocessing of the data streams offered by the mentioned system components and thus ensures a reduction of the data volume to be stored or transferred.

embodiment

The invention will be explained in more detail with reference to a possible implementation variant and an application example of the TOMAS. FIG. 1 shows the basic arrangement of the sensors and serves to illustrate the application example. FIG. 2 shows the structure picture of a possible implementation variant of the TOMAS. Expediently, TOMAS according to FIG. 2 is constructed as follows:

- module PANK (panchromatic channel)

This can be a scanner or a line scan camera in a known manner. The sensor array is preferably manufactured in Si-CCD hybrid technology and has a high precision of the sensor geometry. Due to the falling MTF of the silicon, the incident luminous flux is limited by edge filters at lambda> = 800 nm.

- Module VNIR (spectral and multi-spectral channels in the spectrum)

VNIR ensures the provision of multispectral image data of high spectral and radiometric resolution with spatial congruence of the spectral mapping of each pixel. The current field of view IFOV is a whole multiple (eg 10)

in comparison to the panchromatic channel, in order to be able to assign a grid of panchromatic data to each multispectral pixel for the purpose of structural analysis (mixed pixel identification). VNIR can in a known manner be a multi-spectral scanner, preferably an imaging spectrometer, which contains line or area sensors in the focal plane of a dispersion optical unit.

- Module SWIR (shortwave infrared channels)

The scanner, camera and spectrometer principle are suitable for the realization in a known manner, the wavelength range requiring special optical systems and detector materials (for example PbSi). The detected wavelength ranges must match the atmospheric "window areas" (preferably in the 1.6 and 2.2Mm ranges).

- Module TIR (channels in thermal infrared)

The basic structure is possible when using special IR optics and detector materials (eg HgCdTe) as with SWIR.

The signals coming from the modules and other sensors, such as the front-end sensor VS and the meteorological sensor MS, initially reach a pre-electronic system known per se. Here, first processing steps take place, preferably in the analog signal area. For reasons of interference immunity, it should be striven to have a digital signal sequence already available at the output of this processing unit VE. The tasks of the Vorelektronik also includes the provision of the required for the operation of the sensor elements clocks and voltages. In a further processing unit, sensitivity and dark current differences of the detector elements are corrected (sensor conditioning).

The subsequent data processing (geometric analyzes and corrections, data selection and compression) takes place in a processor system PS taking into account the conditions of admission and specific object features when using the data from the apron sensor and the meteorological sensor as well as from specific process steps stored in a database. In addition, the movement parameters (position orientation, V / H ratio) of the host vehicle, which may be an aircraft or spacecraft, are taken into account. This data can either be taken directly from the Lageorientierungs- and navigation system of the host vehicle or determined with a suitable measuring device of known type for flight data FD.

Further components of the TOMAS not described in greater detail are an operator terminal OT for ensuring interactive work with the system, at least one monitor M for visualizing the recorded image data in real time and storage means SM for recording the processed data.

1 shows the basic arrangement of the recording system 1 and the apron and the meteorological sensor 2 and 3 on a carrier aircraft 4. Furthermore, characteristic features are shown for the description of the application example. A user of a device for the acquisition of remote sensing data would be interested in probing a terrain area of about 10km χ 20km size from various points of view. The area is partly ordered with agricultural crops, the other part cover a forest and a lake. He is initially interested in (A) the condition of large grain fields, where as a result of prolonged drought, hot spots are suspected. Another objective of the investigation is (B) to find favorable mining sites for mineral raw materials (gravel sand) for the construction industry. Forest pests have been discovered in the forest. By means of remote sensing, (C) the source of the disease and the spread of the pest infestation should be determined in order to prepare targeted remedial measures. Ultimately, it is still (D) to determine the concentration and spread of algae in seawater (Entrophierungszustand).

For the solution of the problem (A) information about the vegetation index as well as the gray value distribution in the panchromatic image is needed.

Problem (B) already places higher demands on the spectral resolution. Characteristics of the wanted soil can be the spectral signature in the VNIR and SWIR, but also the moisture storage capacity, which can be reflected in the state of the vegetation above it. With the help of algorithms for identifying these features, deposits can be located with high probability. Certain sections of land (forest, lake) that are not eligible for mining of the minerals sought are excluded from exploration from the outset.

Problem (C) can be solved with certainty if the gray value distribution in the panchromatic image is correlated with a mapping of the temperature distribution (NE ΔΤ <0.3K). For this purpose, data from the TIR module is used. Multispectral data from the VNIR module provides more information about the vitality of the forest.

Problem (D) requires a high radiometric sensitivity and spectral resolution in the blue / green range of the VIS spectral range. Atmospheric effects (turbidity) can play a major role and are eliminated. The concentration of algae in seawater can be determined from the spectral signature with data from the VNIR module. To evaluate the areal distribution, the gray value distribution in the panchromatic image is to be evaluated.

The large differences in the demands on the geometrical, spectral and radiometric resolution of remote sensing data for tasks that may well be present at the same time in a relatively small area of terrain, are clear in this example. Conventional remote sensing systems can not meet these requirements. With the TOMAS device system, these tasks can be accomplished with aircraft flight at a relatively low total cost.

The algorithms for solving the tasks, the amount of data necessary for each task and to be selected from the data offer of the recording system and the necessary data processing steps are determined before the beginning of the recordings and stored in the TOMAS database.

Claims (3)

An arrangement for obtaining remote sensing data using known recording means and a processor system for on-board preprocessing of the image data, a related to the processor system database and means for visualization of the acquired image data in real time and memory modules, characterized in that the arrangement is a programmable Opto-electronic multispectral imaging system (1) featuring a panchromatic, geometrically high-resolution channel, multispectral visible and near-infrared channels with high spectral and radiometric resolution and shortwave and thermal infrared channels, and a meteorological sensor (3) and a sensor for obtaining apron information (2). 2. Arrangement for obtaining remote sensing data according to claim!, Characterized in that the panchromatic channel is realized as a scanner or line scan camera and the size of the respective instantaneous field of view (IFOV) of the multispectral channels is a whole multiple in comparison to that of the panchromatic channel. 3. Arrangement for obtaining remote sensing data according to claim 1 and 2, characterized in that the multispectral channels by an imaging spectrometer, which contains line sensors in the focal plane of a dispersion optics realized.