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X-SAR/SRTM Mission

Announcement of Opportunity

Exploitation of X-SAR/SRTM Data Products

Version September 15, 1998

 

 

Table of Contents

 

1. The Announcement of Opportunity - A General Description

1.1. Introduction

1.2. Objectives

1.3. Data provision

1.4. Reporting

1.5. Funding

 

2. The X-SAR/SRTM Mission

2.1. Mission objectives

2.2. System description

 

3. The SRTM Data Products

3.1. Product description

3.2. Processing and data distribution strategy

 

4. Areas of Applications

4.1. Calibration and validation applications (Area I)

4.1.1 Calibration concept

4.1.2 Validation concept

4.1.3 Proposals for calibration and validation

4.2. Research and scientific applications (Area II)

4.2.1 Radar backscattering and penetration depth

4.2.2 Local incidence angle correction with respect to surface cover

4.2.3 Synergistic use of different sensor systems (and GIS)

4.2.4 Support of geoscientific research in areas of limited cartographic coverage

4.2.5 Update of topographic models for climate models and application of vegetation height

4.3. Demonstration of value-adding and commercial applications (Area III)

 

5. Guidelines for Proposal Preparation

5.1. General conditions and deadline

5.2. Format and contents of the proposal

 

6. Evaluation of Proposals

6.1. Evaluation and selection procedures

6.2. Evaluation criteria

6.3. Follow-on actions and activities

 

7. Schedule

 

8. Contact Addresses

 

Annex

Product Description

1. The Announcement of Opportunity - A General Description

1.1. Introduction

 

The German Aerospace Center (DLR) announces an opportunity to carry out scientific research, calibration experiments and application development in Earth observation using X-SAR and SIR-C data from the first across-track, single-pass interferometric Space Radar Topography Mission (SRTM). The SRTM Mission is a cooperative effort between the US National Aeronautics and Space Administration (NASA), the US National Geospatial-Intelligence Agency (NGA), the Italian Space Agency (ASI) and DLR. The opportunity is open worldwide for candidates submitting proposals which cover the exploitation of SRTM data products within the following topics:

 

I. Calibration and validation of X-SAR/SRTM data products.

II. Research and scientific applications.

III. Demonstration of value-adding and commercial applications.

 

The 11-day SRTM mission is foreseen to be launched in September 1999. Data will be released progressively starting earliest 6 months after the mission.

SRTMís payload will offer the opportunity of doing research in the areas of Earth topography and microwave backscatter fundamentals for calibration and validation of interferometric products. The coverage is between +60 and -58 degrees latitude. At the same time, it will facilitate the development of interferometric Earth observation applications and demonstrate the potential of these data products to support operational and commercial projects. The advantage of being accepted as Principal Investigator is priority and free access to:

1.2. Objectives

 

In line with the overall SRTM mission description presented in Chapter two, this Announcement of Opportunity has the general purpose of

1.3. Data provision

Following the approval of the proposed project by DLR, data sets necessary to carry out the projects will be provided to the selected Principal Investigators free of charge. For proposals requesting large data volumes, data provision will be negotiated on a case-by-case basis prior to the acceptance of the proposal.

All X-SAR/SRTM data will be distributed by DLR's DFD (Deutsches Fernerkundungsdatenzentrum / German Remote Sensing Data Center), except for data over Italian territory, which will be provided by ASI.

The X-band ITED-Level 2 data is intended to be made available starting in summer of the year 2000, the C-band ITED-Level-1 and -2 data should be ready for release by the summer of 2001. The progress of the data preparation may be monitored via Internet.

The SIR-C ITED-2 data will be available for the national territory of Germany, the USA and to-be-determined areas for jointly agreed scientific investigations subject to NASA-NGA data-use-guidelines. SIR-C ITED-1 products will be available globally. X-SAR elevation products will be available globally.

In addition to the elevation data, X-SAR image products will also be available. The image product specifications are described in the Annex, tables 3.3 and 3.4.

It should be noted that all X-SAR/SRTM data will be catalogued and made available to other users. No data supplied in the framework of this Announcement of Opportunity may be transferred, sold or given to third parties other than approved Co-Investigators without the written authorization of DLR.

Prior to the usage of the data the Principle Investigator will have to sign an agreement "Terms and Conditons of Usage of SRTM data" which reflects the legal arrangements agreed upon in the NASA-DLR SRTM and X-SAR MoU concerning data usage.

1.4. Reporting

The progress and accomplishments of the projects selected through this Announcement will be monitored by DLR. All accepted Principal Investigators will be required to submit periodic progress reports describing the status of their work. At the end of the project, a final report in accordance with a given format is mandatory.

Principal Investigators must submit their final reports to DLR in German or English, and present their results at the following milestone workshops organized by DLR: I. Calibration/Validation one year post-mission, II. Scientific Applications two years post-mission, III. Commercialisation three years post-mission (or earlier). They may also be asked to present results or parts of their results at special workshops organized by DLR and NASA.

In order to make research findings available to other data users, all Principal Investigators must provide their project results in a common digital format, which is going to be defined by DLR.

1.5. Funding

In addition to free access to SRTM data, DLR may provide funding to some of the accepted projects of German Principal Investigators.

The DLR Earth Observation Utilization Program will fund a limited number of the selected projects covering topics from calibration/validation science, concerning interferometric methods and the demonstration of commercial applications. Accepted German PIs may apply for DLR funding within the normal application procedure. However, since funding resources of DLR are limited, you may consider to consult other funding agencies, which may support AO-associated projects within the framework of their own programs.

2. The X-SAR/SRTM Mission

 

The participation of X-SAR in the SRTM mission is a highly efficient combination of the Shuttle Radar program by re-using successfully flown space hardware. The mission will provide a huge unique and valuable data set which will satisfy a broad user community such as Earth science, commercial users and governmental institutions. Or, as Dr. Miriam Baltuck, NASA Program Scientist put it: "The topographic information produced from this mission will be the most universally useful data set about the Earth that has ever been produced, excepting measurements from weather satellites".

Information about topography is of major importance to all Earth sciences. Digital elevation models are a prerequisite for any process model concerning, e.g., erosion, vegetation distribution, hydrology or climatology. The importance of topography for the various geoscience disciplines can be summarized as follows:

 

Ecology: Dependency between life forms and geographic location is driven by relief-dependent parameters, i.e., climate, soil, water availability and landscape type;

Hydrology: Investigation about water distribution and run-off in watersheds;

Geomorphology: Description of the Earth's surface with respect to morphological processes;

Climatology: Topography influences meso- and macro-climates through radiation and temperature budget, air circulation and distribution of precipitation.

 

2.1. Mission objectives

With its performance and functional capabilities, the two 1994 radar shuttle missions SIR-C / X-SAR have set new standards for imaging microwave remote sensing sensors from space. They have also successfully demonstrated repeat pass interferometry in all three frequencies (X-, C-, L-band) with a 1-day repeat as well as a 6-month repeat orbit. The well known problem with repeat orbit interferometry is the temporal target decorrelation, unsuitable baselines and different squint angles for the two passes to be processed. Therefore, for the third mission of SIR-C / X-SAR, a single-pass interferometry system with a second receive antenna is proposed to generate a topographic map of all land surfaces between +600 and -580 latitude. The requirement for the topographic mission is to map about 80% of the entire Earthís landmass. The radar instruments will image all land surfaces in ascending as well as descending passes to meet the performance requirements especially for mountainous areas and to minimize the unwanted effects of layover and radar shadow.

Until today, only limited digital topographic maps are available. They vary in geometric resolution and datum and are only partly available to the scientific public. While the only existing global digital dataset has a horizontal resolution of 1 km and a vertical height resolution of 100 m, SRTM will render a 30 m horizontal and 10 m vertical height resolution in the C-band and even a 6 m vertical resolution in the X-band.

2.2. System description

A two-frequency single-pass interferometric SAR is configured by simultaneously operating two sets of radar antennas, one with transmit/receive and one with receive-only antennas separated by a baseline length of 60 m and two receiver channels. X-SARís 12 meter long and 40 centimeter wide main antenna for transmit and receive (channel one) is mounted directly to a tiltable part of the SIR-C antenna truss structure in the Shuttle cargo bay.The second receive-only antenna is 6 meter long and is mounted together with the second 8 meter long C-band antenna (channel 2) on a 60 meter long, deployable, stiff boom structure perpendicular to the velocity direction of the space Shuttle to create the baseline. X-SAR is not capable of operating in a ScanSAR mode like SIR-C which would allow complete coverage of the Earth during an 11-12 day Space Shuttle mission, but it will operate in a high resolution mode with a swath width of about 50 km placed inside the SIR-C ScanSAR swath at an angle of 52 degrees off nadir.

The principle coverage pattern for the X-SAR and SIR-C systems is shown in the figures below. For more detailled information refer to the following web-pages:

 

 AO Coverage GIF

SIR-C/SRTM Coverage Pattern 

 

 

AO XSAR Coverage GIF

X-SAR/SRTM Coverage Pattern

 

3. The SRTM Data Products

3.1. Product description

The main products of the SRTM mission will be digital elevation products. The X-band will map the land surface between +600 and ñ580 in approx. 50 km wide swaths. Full coverage will be possible at latitudes greater than approx. 480 . The C-band radar will completely cover the land surface between +600 and ñ580 degrees. Table 3.1 in the annex describes the specifications of the X-band-derived DEM, Table 3.2 the respective C-band elevation products. A height error map coregis-tered to the elevation product will be available indicating on a pixel-by-pixel basis the quality of the interferometric DEM.

The X-SAR image products additionally available besides the elevation data products are described in the annex, Tables 3.3 and 3.4.

3.2. Processing and data distribution strategy

Processing, archiving and distribution of all X-SAR/SRTM data will be performed at DLRís DFD (German Remote Sensing Data Center), except for the area of Italy. The processing comprises the standard SAR processing including phase unwrapping, DEM generation and data mosaicking. Already during the mission, a considerably large amount of X-SAR data will be transmitted directly to NASAís Jet Propulsion Laboratory (JPL). These data will be used for system checks, system verification, calibration and product validation for selected areas. Additionally, a certain amount of data will be sent to DFD during the mission via high speed data networks. These data are open for public relations activities during the mission, general mission support, for checking of the processing facilities and for the cooperating calibration/validation teams.

Upon mission completion, all data will be copied to special D2-cassette tapes at JPL and transported to DFD. After this, the screening of the whole data set will take place. This process is the main task of the commissioning phase when all raw data will be archived, raw data statistics derived, calibration performed and automatic high throughput processing prepared. This phase will last at least 6 months. During this phase, selected sites of calibration/validation proposals will be processed according to a priority schedule defined pre-mission by DLR (see below).

After the initial data screening, the standard processing will begin. This phase will last until all X-SAR data have been processed to digital elevation models and images, approximately two years. The products will be archived in the DFD robot archive and made available to the user via a WWW-customer and user interface. On the website the current processing status of the DEMs will be shown.

The priority scheduling will take into account special needs for fast product delivery and calibration/validation support. The DFD will make available the X-SAR/SRTM products following an optimized schedule which will be set up after the evaluation of the AO proposals. The schedule may be revised after the commissioning phase.

The data orders will be accepted at at DFDís multi-mission user interface (MUIS) within the WWW-home page of the DFD. The user will be asked for his identification. After validation he may specify the requested area (by coordinates or by map browser) and the desired product type (clickable scroll bar items). The system checks for the information given and returns the estimated delivery time.

SRTM-products will be distributed either by CD-ROM or electronically (preferred) together with accompanying product information.

The following priority levels will be applied:

 

Priority Levels

Areas of prioritized Data Processing and Distribution

Level 1:

Mission requirements

Level 2:

Public information activities

Level 3:

Calibration and validation

Level 4:

Principal Investigator orders

Level 5:

Non-PI orders

 

4. Areas of Applications

4.1. Calibration and validation applications (Area I)

Proposals are invited which support the calibration and validation of the X-SAR interferometric data products by providing accurate terrain height information either as ground control points, kinematic GPS tracks or reference DEMs. Although proposals are sought for both calibration and validation, contributions for the latter are particularly welcome. However, depending on the geographic distribution of the available ground truth information the project will decide on whether to use the data for calibration or validation. The intended approach for calibration and validation is outlined in the following sections.

 

4.1.1 Calibration concept

The X-SAR system calibration includes two parts: the radiometric and the interferometric calibration. The high radiometric accuracy of the X-SAR during SRL-1/2 will be verified using ground receivers and rain forest data for antenna pattern measurements, and corner reflectors for absolute calibration. Here, we concentrate on interferometric calibration including X-SAR instrument phase calibration, and InSAR imaging geometry calibration.

The most critical parts of the X-SAR electronics are the boom cables, where high temperature variations between -50oC and -10oC are expected. Another problematic section is the path from the six panels of the secondary antenna to the combiner box including the phase shifters for beam steering. Electronic steering effectively tilts the antenna aperture and results in a shift of the phase center. Corrections require a precise knowledge of the behaviour of these phase shifters.

Instrument phase calibration includes three major parts:

The shuttleís boom will provide a mechanical fixed baseline that will enable an interferometric imaging from parallel orbits. Nonetheless, possible boom dynamics, caused by the shuttleís orbit maintenance maneuvers, gravitational effects, and boom twisting due to thermal effects may cause changes of the attitude of the secondary antenna and, therefore, may vary the interferometric baseline. The use of the so-called Attitude and Orbit Determination Avionics (AODA) system, that includes GPS receivers, star trackers, inertial reference units, optical trackers, and electronic distance meters, will allow an accurate relative measurement of the interferometric baseline vector. It will further provide antenna attitudes, orbital state vectors, and the time-base for both radar systems.

However, systematic errors in the AODA measurements due to offsets in the mounting of the AODA instruments and thermal variations during the flight may affect the measurement accuracy of both the baseline length and tilt angle. A calibration of this measurements can be performed by evaluating data sets acquired over areas with well-known height (e.g., ocean or reference data provided by Principal Investigators). Additionally, for the radiometric calibration, corner reflectors deployed at calibration test sites will be used to estimate the range delay and a possible time-tag offset. A differential range delay that may occur between the two interferometric channels will be estimated during image co-registration.

4.1.2 Validation concept

The validation of the interferometrically (InSAR) derived DEMs will be performed in two steps. A project internal validation will be carried out during the commissioning phase (ending 6 months after the mission) by a DLR team consisting of colleagues from SAR/InSAR processing and calibration. The project validation will concentrate on selected sites and will include a cross-validation with C-band results.

Furthermore, we particularly invite investigators to propose validation experiments for the standard SRTM products. PIís will receive InSAR DEMs and use their own reference data for validation. InSAR DEM validation has to consider the type and height of vegetation cover and the frequency dependent canopy penetration. Statistical analyses will be performed and compared with the annotated error map.

4.1.3 Proposals for calibration and validation

Proposals, which aim to contribute to the calibration and validation process, will have to indicate clearly the:

Reference data should be in WGS84 (horizontal and vertical datum). Source and accuracy of the reference data have to be clearly specified. Reference data could be:

including buildings, road intersections, railway tracks, bridges, dams

4.2. Research and scientific applications (Area II)

A non-exclusive list of examples for scientific proposals spans the following areas:

4.2.1 Radar backscattering and penetration depth

Enhancement of knowledge about radar backscattering and penetration depth. Since X- and C-band radar signals only partly penetrate through vegetation, the interferometric DEMs represent the terrain height plus an unknown vegetation height (see also 4.1.2). Investigation of the location of the scattering medium for a variety of surface types is, therefore, a desirable information to determine the true terrain elevation.

4.2.2 Local incidence angle correction with respect to surface cover

Radar backscattering is differently depending on the incidence angle for various surface covers or roughness heights. Since the local incidence angle varies with topography, a valid angle correction (e.g., for classification or sensor synthesis) is only possible if the relief and the surface-specific backscatter characteristics are known. Proposals should address representative surface or vegetation types to establish a catalogue.

4.2.3 Synergistic use of different sensor systems (and GIS)

Digital Elevation Models are a pre-requisite for geo-coded satellite images and correct terrain effects in radar scenes. Since availability of DEMís has been limited in the past, development of synergistic analysis techniques for various microwave and optical remote sensing images in areas of (high) relief has only been poorly developed. Proposals should specify why synergistic sensor evaluation promises advantages and how the issue of merging will be approached.

4.2.4 Support of geoscientific research in areas of limited cartographic coverage

Proposals shall list restrictions or difficulties due to limitations of available topographic information and clearly specify the geoscientific advances which are to be expected through the use of the SRTM Digital Elevation Models.

4.2.5 Update of topographic models for climate models and application of vegetation height

The scientific advancement due to the increased geometric resolution using SRTMís elevation model shall be demonstrated for specific and well-defined applications, e.g., climate or watershed models. Alternatively, innovative use of the "top-of-the-canopy" elevation model shall be developed.

4.3. Demonstration of value-adding and commercial applications (Area III)

The development of operational and commercial applications of SRTM data is of particular interest to the German Earth Oberservation Programme. It will lead to the expansion of applications and the expansion of the market for value-added services.

Proposals are expected from or in close cooperation with the service industry or value-adding companies.

Commercial applications related to SRTM Digital Elevation Models are for example

Proposals are also sought which address research and development activities required in support of future commercial utilization of SRTM data products. Relevant information may be derived from SRTM data alone or in conjunction with other data sources. Such proposals may also include the definition of new products or algorithms required for the development of such applications.

Candidates should define the objectives, scope and implementation of their projects as accurately as possible along with a potential transition into market-oriented services. The implementation plan should also indicate the ways and means necessary for attaining such objectives.

Information of a proprietary nature contained in any proposal will be used by DLR for evaluation purposes only. Should any proposer out of Area III wish the details of the proposal other than the title to be considered as confidential during the course of the project, he should indicate this in the proposal. Nevertheless the PI will have to provide the regular progress reports to DLR and present his final results. The final report will be published.

5. Guidelines for Proposal Preparation

5.1. General conditions and deadline

Proposals have to be submitted electronically in WORD 6.0 format to:

 

Peter Ritter/DLR-Bonn

Section RD-JE

e-mail: peter.ritter@dlr.de

 

Any deviations from the above mentioned format need to be approved by DLR prior to submission of the proposal.

The submission deadline is November 30, 1998 at midnight and no proposal received after the deadline will be accepted.

DLR may decide to select only a portion of the proposer's investigation, in which case the investigator will be given the opportunity to accept or decline such partial acceptance.

5.2. Format and contents of the proposal

The proposal should be submitted by the investigator, or official of the investigator's organisation, who is authorised to commit the organisation to the contents of the proposal.

The proposal shall be composed of six components.

 

(Name, Organization, Street, City, Mailcode, Telephone, Fax, e-mail)

(Area I, II or III)

(Type, Coordinates in UTM of testarea)

(will be treated confidential)

 

a. Executive Summary: This should provide a brief description of the objectives and the proposed approach. (Max. 20 lines of text)

 

b. Expected Results: This should summarise the expected outcome and benefit of the proposal. (Max. 6 lines of text)

 

c. Team Composition: The management approach, organisation and division of the work by the Principal Investigator and his relationship with the Co-Investigators, if any, to be listed here, and the overall staffing level shall be summarised. (Max. 12 lines of text)

 

d. Schedule: The proposal should include a description of the main tasks envisaged, together with their corresponding schedules. (Max. 6 lines of text)

 

e. Detailed Proposal: As appropriate, this section should, in a concise form, include the scientific, application oriented or commercial objective(s), the proposed approach or methodology, a reference to previous experience and other projects whenever applicable, the benefiting applications and/or users, the market size and the demand, the potential funding approach, any potential problems. (Max. 120 lines of text)

 

In the event that ancillary data is crucial to the success of the proposed investigation, the proposal must clearly indicate the adequacy and feasibility of any plan to acquire these data.

6. Evaluation of Proposals

6.1. Evaluation and selection procedures

Proposals received in response to this Announcement of Opportunity will be reviewed by panels composed of:

 

 

Proposals will be rejected where results are not timely. DLR may propose adjustments to milestones to achieve mission goals.

6.2. Evaluation criteria

The following criteria will be used in the evaluation process:

 

        1. Relevance of the proposed project to the objectives of the SRTM mission and in particular of this Announcement of Opportunity.
        2. The merit of the project from the missionís technological, scientific and economic viewpoint and the degree of innovation of the proposal.
        3. The technical feasibility of completing the project and achieving positive results within a period of two years after receipt of the data, with special emphasis on the adequacy and practicability of the schedule presented in the proposal.
        4. The competence and relevant experience of the Principal Investigator and collaborators, as an indication of their ability to complete the project successfully.

6.3. Follow-on actions and activities

Following notification, the selected Principal Investigators, will have to

In some cases the Principal Investigator will be required to amend his proposal in order to meet the acceptance criteria and in accordance with the remarks expressed by the evaluators.

A briefing meeting for selected Principal Investigators will be held in spring of 1999.

7. Schedule

Release of Announcement of Opportunity

September 15, 1998

Deadline for submission of proposals

November 30, 1998

Notification of evaluation results to Principal Investigators

February 28, 1999

 

8. Contact Addresses

 

The following persons may be contacted for further information:

Dr. Christiane Schmullius/DLR-Oberpfaffenhofen

NE-HF

e-mail: Chris.Schmullius@dlr.de

Achim Roth/DLR- Oberpfaffenhofen

DFD

e-mail: achim.roth@dlr.de

Manfred Zink/DLR-Oberpfaffenhofen

NE-HF

e-mail: manfred.zink@dlr.de

    • Value Adding/Commercialization Aspects:

Wolfgang Noack/DLR-Oberpfaffenhofen

DFD

e-mail: wolfgang.noack@dlr.de

    • AO-funding Aspects:

Peter Ritter/DLR-Bonn

RD-JE

e-mail: peter.ritter@dlr.de

 

Annex

 

Product Description

 

Description

SRTM X-SAR Elevation Products

Level-2 Terrain Height Maps

Accuracy Specifications

Absolute Horizontal Accuracy

Relative Horizontal Accuracy

Absolute Vertical Accuracy

Relative Vertical Accuracy

 

90% Circular Error < 20 meters

90% Circular Error < 15 meters

90% Linear Error < 16 meters

90% Linear Error < 6 meters

Spatial Resolution

30 m x 30 m

Horizontal Datum

WGS 84

Vertical Datum

WGS 84 ellipsoid

Product Format

Block Definition

Reference Origin

Data Record Sequence

Data Value Sequence

Posting

N ñ S

N ñ S

Data Format Representation

Physical Units

 

fixed, 15ë raster in lat and long

Southwest corner

Ascending (west to east) longitude

Ascending (south to north) latitude

Latitude Longitude

1 arcsec 1 arcsec

1 arcsec 2 arcsec

16-bit signed integer

meters

Medium of Distribution

CD-ROM / INTERNET

Table 3.1: X-SAR Elevation Product Description

 

(For the Elevation Products, Error Maps will be provided in the same format)

 

Description

SRTM SIR-C Elevation Products

Level-1 Terrain Height Maps

Level-2 Terrain Height Maps

Accuracy Specifications

Absolute Horizontal Accuracy

Relative Horizontal Accuracy

Absolute Vertical Accuracy

Relative Vertical Accuracy

 

90% Circular Error < 20 meters

90% Circular Error < 15 meters

90% Linear Error < 16 meters

90% Linear Error < 10 meters

 

90% Circular Error < 20 meters

90% Circular Error < 15 meters

90% Linear Error < 16 meters

90% Linear Error < 10 meters

Spatial Resolution

30 m x 30 m

30 m x 30 m

Horizontal Datum

WGS 84

WGS 84

Vertical Datum

WGS 84 ellipsoid

WGS 84 ellipsoid

Product Format

Block Definition

Reference Origin

Data Record Sequence

Data Value Sequence

Posting

N ñ S

N ñ S

Data Format Representation

Physical Units

 

fixed, 15ë raster in lat and long

Southwest corner

Ascending (west to east) longitude

Ascending (south to north) latitude

Latitude Longitude

1 arcsec 3 arcsec

1 arcsec 6 arcsec

16-bit signed integer

meters

 

fixed, 15ë raster in lat and long

Southwest corner

Ascending (west to east) longitude

Ascending (south to north) latitude

Latitude Longitude

1 arcsec 1 arcsec

1 arcsec 2 arcsec

16-bit signed integer

meters

Medium of Distribution

CD-ROM / INTERNET

CD-ROM / INTERNET

Table 3.2: SIR-C Elevation Product Description

 

 

 

Product Parameter

X-SAR Standard Image Products

MGD

Multi-Look, Ground Range, Detected

SSC

Single-Look, Slant Range, Complex

Equivalent Number of Looks

in Azimuth

in Range

 

1.5 ñ 2.5

1 ñ 3

 

1

1

Geometric Representation

Ellipsoid used

Ground Range

GEM 6

Slant Range

n.a.

Data Representation

Pixel quantization

Detected, amplitude

16 bit, signed integer

Complex,

16 bit real, 16 bit imaging

Ground Area Covered

Azimuth

Range

Ý

> 100 km

< 49.0 km

Ý

> 100 km

Product Orientation

Zero Doppler coordinates

Zero Doppler coordinates

ISLR (1-D)

PSLR (1-D)

SAAR

> 14 dB

> 17 dB

> 20 dB

n.a.

n.a.

n.a.

Spatial Resolution

Azimuth

Range

 

25 m at mid swath

25 m at mid swath

 

8 ñ 12 m

coarse 17 m, fine 8.5 m

Absolute Location Error (1s )

Azimuth: 3,0 km

Ground Range: < 3.9 km

Azimuth: 3,0 km

Ground Range: < 3.9 km

Pixel Spacing

Azimuth

Range

 

12.5 m

12.5 m

 

1/PRF = 3,9 m ... 5.8 m

c. 13.3250 m , fine 6.6625 m

Number of Pixels

Azimuth

Range

 

> 8000

< 5000

 

max. 30000 (complex)

max. 3870 (complex)

Image data volume

up to 80 Mbytes

up to 358 Mbytes

Medium of Distribution

Exabyte/CD-ROM

Exabyte/CD-ROM

Table 3.3: X-SAR/SRTM Standard Image Product Description

 

 

Product Parameter

X-SAR Geocoded Image Products

GTC

Terrain Corrected

GIM

Incidence Angle Mask

Equivalent Number of looks

in Azimuth

in Range

 

1.5 ñ 2.5

1 ñ 3

 

n.a.

n.a.

Geometric Representation

Ellipsoid used

Cartographic UTM

WGS 84

Cartographic UTM

WGS 84

Data Representation

Detected, amplitude

Bit 0 = layover

Bit 1 = shadow

Bit 2-6 = incidence angle

Pixel Quantization

16 bit, signed integer

16 bit, signed integer

Ground Area Covered

Azimuth

Range

Ý

> 100 km

< 49.0 km

Ý

> 100 km

< 49.0 km

Product Orientation

x-axis

y-axis

 

easting

northing

 

Easting

Northing

Spatial Resolution

25 m

25 m

Absolute Location Error (1s )

< 30 m

< 30 m

Pixel Spacing

northing

easting

 

12.5 m

12.5 m

 

12.5 m

12.5 m

Number of Pixels

northing

easting

 

8000 - 10000

4000 - 10000

 

8000 - 10000

4000 - 10000

Image Data Volume

up to 160 Mbytes

up to 160 Mbytes

Medium of Distribution

Exabyte/CD-ROM

Exabyte/CD-ROM


Table 3.4: X-SAR/SRTM Geocoded Image Products


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