SAR PRODUCT GUIDE - Iceye · SAR Product Guide - V. 3 4 / 36 f l ex IC on f ConT enT s f f Product...

www.ICEYE.com

Version 3.3Released: 30.06.2020

S A RP R O D U C TG U I D E

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1. Introduction 1

2. Lexicon 2

2.1 Definitions And Acronyms 2

2.2 Symbols 4

2.3 glossary 5

3. SAR Instruments And Orbits 6

3.1 ICEYE SAR Instruments 6

3.2 Orbit Parameters 8

4. Brief SAR Technical Overview 10

4.1 Resolution 10

4.1.1 Range Resolution 10

4.1.2 Slant Range vs. Ground Range 11

4.1.3 SAR Azimuth Resolution 12

4.2 Calibration 13

4.2.1 Radiometric Calibration 14

4.2.2 Radiometric Accuracy 16

4.2.3 Geolocation Accuracy 16

4.2.4 Focusing Calibration 17

5. Product Specifications 18

5.1 Standard ICEYE Products 18

5.2 ICEYE Imaging Modes 18

5.2.1 Stripmap Imaging Mode 18

5.2.2 Stripmap High Imaging Mode 19

5.2.3 Spotlight Imaging Mode 20

5.2.4 Spotlight High Imaging Mode 20

5.3 ICEYE Data Products Formats 22

5.3.1 Level-1 Single Look Complex (SLC) Products 22

5.3.2 Level-1 Ground Range Detected (GRD) Products 23

5.3.3 Level 2 - Geocoded Products 26

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5.4 ICEYE Data Format 26

6. SAR Product Ordering 28

6.1 Introduction To SAR Product Orders 28

6.2 New Image Tasking Order Flow 28

6.2.1 Order Submission 29

6.2.2 Event Planning and Acquisition Scenario 29

6.2.3 Image Tasking, Satellite Imaging and Image Downlinking 30

6.2.4 Quality Control 30

6.2.5 Image Delivery to Customer 30

6.2.6 Off-nominal Scenarios 30

6.3 Order Flow For Archive Images 31

6.3.1 Order Submission 31

6.3.2 Order processing 32

6.4 Order Cancellation 33

6.5 Invoicing 33

7. Support 34

7.1 Customer Success Team 34

7.1.1 Working hours 34

7.1.2 Contact Information 34

8. References 35

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1 / 36SAR Product Guide - V. 3

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1 . I n T r o d u C T I o n

SCOPE OF THE DOCUMENTThe ICEYE SAR Product Guide provides ICEYE Customers with SAR Prod-

uct Specifications, a detailed description of the Image Ordering process, and

related Supporting information. Details of imaging modes and sensor perfor-

mance metrics are also provided.

Chapter 3 of the Guide provides a high level overview of the ICEYE Constella-

tion and provides useful satellite and orbit parameters.

Chapter 4 then presents a high level technical guide on synthetic aperture

radar and calibration. It is provided here to add context and relevant informa-

tion to the SAR products discussed in Chapter 5.

Chapter 6 describes the ICEYE product ordering process.

Finally, chapter 7 explains how customers can arrange support from ICEYE

using ICEYE’s Customer Success team.

DISCL A IMERThe materials presented in this document are for informational purposes

only. The products and services it describes are subject to change without

prior notice. ICEYE makes no representations or warranties with respect to

this product guide or with respect to the products or services described herein.

ICEYE shall not be liable for any damages, losses, costs or expenses, whether

direct, indirect or incidental, consequential or special, arising out of, or

related to the use of this material or the products or services described herein.

CONSTELL AT ION OVERV IEWThe ICEYE constellation, as of April 2020, consists of three X-band Synthetic

Aperture Radar (SAR) satellites. Throughout 2020 and 2021, the constella-

tion is expected to grow to 18 satellites in specialised orbital planes designed

to provide a near persistent fine resolution view of The Earth’s surface. The

ICEYE vision is to bring a new service to the market with an emphasis on

superior reliability, a vastly higher rate of revisits to individual locations, and

an unprecedented objectivity. The service is based on a completely new satel-

lite and sensor design, leveraging recent advancement in various technologies

and a New Space approach.


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2 . l e x I C o n

2 . 1 D E F I N I T I O N S A N D A C R O N Y M S

AASR - Azimuth Ambiguity to Signal Ratio

Acquisition - SAR satellite imagery acquired over a given area of interest

Acquisition scenario - a plan of the imaging events created to generate

imagery coverage over a specified area of interest

Acquisition time - period of time described in UTC when the satellite

images an area of interest

AOI (Area Of Interest) - geographic point, strip or area selected by the cus-

tomer for new acquisition or archive delivery

Archive imagery - satellite imagery previously acquired

Azimuth direction - direction of the satellite’s flight path

Customer - the individual or organization purchasing SAR imagery products

from ICEYE

Customer Employee - an employee / representative of the organization

authorized to place orders, or take any other action stated in the contract

Customer Success - Department of ICEYE Oy in charge of the order pro-

cessing and support of the Customer Organisations

Customer Success Specialist (CSS) - Customer Success team employee

DEM - Digital Elevation Model

DN - Digital Number

Event - corresponds to the tasking of one image acquisition within an order.

Each event has a unique ID attributed to it automatically


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Image ID - numeric code attributed automatically to the event for tracking

purposes. Image ID has to be mentioned in any communication with the Cus-

tomer Success team

Frame - Area of the acquired image

GRD - Ground Range Detected

Image - file that encloses the frame taken by the satellite according to the

tasked event

Image processing - The process of converting collected radar pulses into an

image

IRF - Impulse Response Function

LTAN - Local Time of Ascending Mode

LTDN - Local Time of Descending Mode

NESZ - Noise Equivalent Sigma Zero

Order - Request for acquisition. The customer shall submit at least an AOI

to the Customer Success team. Other acquisition parameters can be specified

such as the acquisition time frame, the angle, the flight direction, etc. Within

one order there can be several image acquisition or events

Order ID - alphanumeric code attributed to the order for tracking purposes.

Order ID has to be mentioned in any communication with the Customer Suc-

cess team

Order placement - order input done by the customer

Organization - a legal entity that has a valid contract for the delivery of the

SAR images with ICEYE

PRF - Pulse Repetition Frequency


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Product - satellite imagery product supplied by ICEYE Oy according to the

specified requirements such as coordinates, acquisition time, angle etc.

Range - direction orthogonal to the direction of satellite’s flight

RASR - RangeAmbiguity to Signal Ratio

SAR - Synthetic Aperture Radar

SLC - Single Look Complex

SFTP (Secure File Transfer Protocol) - a secure gateway that ICEYE

employs in delivering products to customers to ensure the file transmission

will be secure

2 . 2 S Y M B O L S

β0 Radar Brightness

ƒsr Range Sampling Rate (Msps - Mega (1024) samples per

second)

θloc Local incidence angle on ground calculated using the

ellipsoidal Earth model (degrees)

σ0 Mean clutter radar cross section (m2/m2)

t Time (seconds)


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2 . 3 G L O S S A R Y

Azimuth - Direction aligned with the relative spaceborne platform velocity

vector.

Detection - Processing step in which the phase information is removed and

only the signal amplitude is preserved. Normally the detection uses a magni-

tude squared method and has units of voltage square per pixel.

Focusing - Data processing finalized to focus the SAR image in range and

azimuth through bidimensional signal compression.

Ground range - Projection of the slant range into the ground.

Incidence angle - Local incidence angle on ground calculated using the ellip-

soidal Earth model.

Looks - The number of lower resolution images (using only a subset of the

full collected spectrum) used to form the complete image. Individual looks are

first ‘Detected’ and then averaged together. This can be performed in either

the range or azimuth dimension and is normally used to reduce the speckle

noise from SAR images. (called multi-looking).

Range - Direction orthogonal to the satellite velocity.

Slant range vector - Line-of-Sight vector between the satellite’s antenna and

the target on ground.

Slant range plane - Plane containing the relative sensor velocity vector and

the slant range vector for a given target.

Spotlight - In the spotlight acquisition mode the spacecraft is mechanically

steered to increase the integration time over a fixed target. The increased

integration time allows a finer azimuth resolution to be attained.

Stripmap - In the stripmap acquisition mode the antenna beam has a fixed

pointing direction with respect to the platform; the beam direction forms an

angle with the vertical passing by the satellite, defined elevation angle.


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3 . s a r I n s T r u m e n T s a n d o r b I T s

3 . 1 I C E Y E S A R I N S T R U M E N T S

The ICEYE Constellation in early 2020 consists of three 85kg (microsatel-

lite) SAR sensors orbiting in a low Earth orbit (LEO). Each satellite carries a

payload that consists of a synthetic aperture radar sensor and antenna. This

Section will describe the characteristics of these instruments and the next

section will provide orbit details.

Each ICEYE satellite operates in the X-band part of the electromagnetic spec-

trum and uses an active phased array antenna that can provide electronic

beam steering. This is used in addition to the satellite’s mechanical agility to

point a radar beam precisely onto the earth’s surface. This agility also allows

the beam to be directed towards the right or left side of the satellite track. The

flexibility of the satellites allows imaging modes to be constantly evolved.

Currently the satellites operate in two primary modes called ‘Spotlight Mode’

and ‘Stripmap Mode’ with each mode providing different output imaging

capabilities depending on the tasking and exploitation requirements. The

details of these modes are covered in Chapter 3.

Each radar pulse can be digitally programmed to modulate over a bandwidth

between 10 and 300MHz centred on the X-band (9.6GHz) part of the spec-

trum. The pulse repetition frequency (PRF) can be selected between 2 and

10 kHz and the peak transmitted power can be as much as 4kW. The instru-

ment’s nominal operating parameters can be seen in Table 1 (next page).



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PARAMETER SPECIFICATIONS

X2 X4 X5

SYSTEM PARAMETERS

Carrier frequency 9.65 GHz (X-band)

Look direction both LEFT and RIGHT

Antenna size 3.2 meters (along-track ‘X-axis’) x 0.4 meters

PRF 2-10 kHz

Range Bandwidth 10-300 MHz

RF Peak Power 4 kW

Polarization VV

Incidence angle range 10-35 (mode dependent)

Mass 85 kg 85 kg 85 kg

Communication [radar payload data

downlink]

X-band 100 Mbits/s X-band 140 Mbits/s X-band 140 Mbits/s

Table 1. System parameters of ICEYE sensors



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3 . 2 O R B I T P A R A M E T E R S

Figure 1. ICEYE-X2 Satellite

A typical instrument of the ICEYE constellation can be seen in Figure 1. Each

satellite is in a sun-synchronous orbit with a nominal 18-22 day ground track

repeat cycle (depending on satellite) with 15 imaging orbits per day. Each orbit

plane is phased around the earth with a different local time of ascending node

(LTAN). This means that the constellation as a whole has the ability to observe

a location at different times of the day rather than the more conventional

dawn-dusk sun-synchronous orbit.

Currently the LTANs are not uniformly spaced which means that the time

to revisit a location on the equator varies with higher and lower rates over a

period of days. The mean revisit rate at the equator is 20 hours with higher

and lower latitudes being revisited more frequently. Table 1 lists the orbital

parameters of the current SAR instruments.



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X2 X4 X5

Nominal Altitude 570 km 570 km 570 km

Inclination 97.69° 97.68° 97.68°

Orbits / Day 15

Ground track repeat 18 days 22 days 22 days

Constellation mean revisit at equator 20 hours

Nodal crossing Nominal value: 10:30

LTDN

Nominal value: 15:05

LTAN

Nominal value: 15:05

LTAN

Table 2. Constellation parameters


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4 . b r I e f s a r T e C h n I C a l o v e r v I e w

This section will provide a high level summary of some of the guiding

principles of synthetic aperture radar operation. It is provided here to add

context and explanation to the following sections on imaging modes. For

more detailed understanding of SAR capabilities, the reader is referred to the

excellent ESA SAR course [1], and the ICEYE Technical Blog Posts [2], [3]. The

chapter starts with a brief introduction to resolution and how it is achieved

using ICEYE’s SAR systems. The next section will discuss calibration tech-

niques applied to the ICEYE Constellation so that precise radar reflective

properties can be extracted from ICEYE SAR image products.

4 . 1 R E S O L U T I O N

The resolution of a radar image refers to the ability to distinguish (i.e. resolve)

between features that are very close together. During image acquisition, all

radar pulses reflected from each feature on the ground are received by the

antenna and registered. In data processing these pulses are used to build the

image scene. This can be done with arbitrary sample spacing, but the reso-

lution defines how well we can separate different point scatterers from each

other. This ability depends on the bandwidth of the signal, and in the follow-

ing we explore what that actually means.

In the case of SAR images, there are two separate dimensions of mea-

surement: the flight direction of the sensor, called azimuth, and the look

direction, which is perpendicular to the flight direction and called range.

The available bandwidth and thus resolution for either of these dimensions

is dependent on different parameters, so we will cover them separately in the

following two chapters.

4 .1 .1 RANGE RESOLUT IONMost radar systems use ‘chirped’ signals. Instead of sending short pulses

with a constant frequency, long pulses are transmitted that sweep up or down

in frequency (hence the term chirp). The extent of the frequency sweep is

known as the pulse bandwidth or radar bandwidth. After data acquisition, the

known frequency sweep can be used to compress the energy in the long pulses

into shorter pulses that appear brighter in the final image. In digital signal

processing terms, this is cross-convolution of the sampled received signal

with the generated reference signal. The ‘half-power width’ of the resulting

compressed pulses is known as the range resolution and is dependent on the


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bandwidth of the transmitted pulse. The digital sampling rate of the system

needs to be high enough to satisfy the Nyquist requirement for recording the

full signal bandwidth. But adding more sampling rate will not increase the

range resolution, even if the sample spacing decreases.

4 .1 . 2 SL ANT RANGE VS. GROUND R ANGEThe time it takes a pulse to be reflected from the ground back to the radar sen-

sor is precisely measured and, as the speed that the pulse travels is constant

(the speed of light), the distance traveled by the pulse can be calculated. This

direct measure of range from the sensor to a scatterer location is known as the

slant range.

The radar image is formed by recording samples over a range window. This

is the time (and therefore distance) for recording each pulse. Radar sensors

don’t have enough memory to constantly record so the data recorder is opened

to only listen to the reflection from the part of the ground of interest. This

opening to the pulse echoes is called the range window and occurs once for

every pulse. These recorded samples are evenly spaced and the length of the

range window determines the size of the image in the range direction.

Figure 2. Ground range image size changes with the incidence angle.


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It can be seen from Figure 2 that the size of the collected image on the earth’s

surface varies with imaging geometry. If the same range window size is used,

then the image size on the ground will be larger when the incidence angle is

smaller. It can also be seen that the earth’s curvature causes the ground sam-

ples to have different lengths when the slant range samples are uniformly

spaced. These effects make the SAR image appear distorted when looked at

in this ‘native’ collection geometry. To make the images appear to represent

the actual ground, a slant-range to ground-range transformation is applied.

After this transformation, the ground range geometry represents the true

horizontal distance between objects on the ground. A consequence of this

transformation is that the ground range resolution becomes finer at larger

incidence angles as the slant range becomes more aligned with the ground. In

the extreme case where the incidence angle is 90 degrees, the ground range

resolution would be equal to slant range resolution.

4 .1 .3 SAR A Z IMUTH RESOLUT IONIn a basic (non-SAR) radar system, the azimuth resolution depends purely

on the length of the antenna aperture: the longer the antenna, the narrower

the radar beam is and the finer the resolution (the ability to tell two scatter-

ers apart from each other) becomes. Since the length of a real-aperture radar

antenna has physical and technological limits, the so-called synthetic-aper-

ture radar (SAR) was developed.

SAR systems synthetically increase the antenna size by using the forward

motion of the satellite during acquisition. As the satellite passes a certain

area, thousands of pulses are transmitted and reflected back to the sensor

sequentially. By recording and combining the individual pulses, a ‘synthetic

aperture’ is created in the SAR image formation processor which results in a

significantly improved azimuth resolution.

The image formation processor uses the Doppler effect, caused by the radar’s

motion past a scene, to focus the signals during the azimuth processing. The

area on the ground is illuminated by the radar beam with several pulses

during a satellite pass. When the moving beam is in the direction towards a

scene, the Doppler shift is positive since the distance between the sensor and

the scene is decreasing. By the time the antenna is at the side of the scene, the

received Doppler shift is zero. After that, the Doppler shift becomes negative

as the satellite is moving away from the scene.


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The azimuth resolution of a synthetic aperture system is dependent on the

total extent of these Doppler shifts, called the Doppler bandwidth. In a sim-

ilar way to the range resolution, the azimuth resolution is determined by the

size of this bandwidth. In order to achieve the finest resolutions, a spotlight

mode is used. In this collection mode the satellite adjusts its beam pointing to

illuminate a single location on the ground for a longer duration. This extends

the amount of energy and Doppler bandwidth collected from the scene.

Conversely from the range dimension, where slant and ground resolutions are

different depending on the incidence angle, in the azimuth dimension there

are only small incidence angle effects, the azimuth resolution in the ‘native’

slant plane converts directly to the ground plane with no meaningful change

in resolution.

4 . 2 C A L I B R A T I O N

A key strength of SAR is that it is also a precise measuring instrument as a

well as a mapping tool. It is therefore possible to obtain radar reflective prop-

erties from the scene by analysing the digital numbers (DN) within the SAR

image. To achieve this, the imbalances and dispersions within the radar and

SAR processor have to be corrected for. This is the purpose of calibration and

will be covered in this section. ICEYE satellites use a range of calibration sites

around the world as well as internal closed loop calibration checks performed

during the engineering process. The key calibrations performed on ICEYE

satellites are :

f Radiometric calibration

f Geolocation accuracy

f Synthetic aperture focusing calibration

f Resolution

f Sidelobes

Each of these will now be discussed at a high level. More detailed information

on ICEYE SAR calibration can be found in the ICEYE Technical Documenta-

tion Library [4]


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4 .2 .1 RADIOMETRIC CAL IBR AT IONRadiometric calibration is required to associate the digital numbers (DN)

within a SAR image with the mean radar cross section σ0 (also known as the

backscatter coefficient ‘sigma-zero’) in m2/m2. The calibration compensates

for effects due to:

f The atmosphere (delay and oscillations of the signal during tropo-

spheric and ionospheric propagation)

f The antenna (distribution of radiated energy in range and azimuth)

f The electronic instrument (variation of transmitted power and receiver

gain)

f The processor (contributions due to the implemented SAR image for-

mation algorithm)

An area of the ground with a given backscatter coefficient σ0 in a SAR Prod-

uct will have a different observed brightness (and hence different digital

number in the SAR image) when the terrain is angled towards the sensor. This

can be calculated from:

σ0 = β0 sin(θloc) – NESZ

Where β0 is the observed radar brightness and θloc is the local incidence angle

of the scattering area. NESZ is the ‘noise equivalent sigma zero’ and rep-

resents the noise component that inherently exists within the pixel in terms

of a mean radar backscattering coefficient. β0 can be obtained from an ICEYE

image from:

β0 = ks |DN|2

Where ks is the calibration factor or calfactor provided in the image meta data

and DN is the digital number of the pixel value given by:

|DN|2 = I2 + Q2

With I and Q being the inphase and quadrature components of the complex

image pixel. Finding the noise component NESZ is the primary purpose of

calibration. The NESZ value however is also a function of standoff range and

local incidence angle and so can be considered in terms of a minimum radar

brightness β0 as:


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NESZ = NEBZ sin(θloc)

Where NEBZ is the noise floor of the radar system in terms of observed

radar brightness β0. The backscatter coefficient for a SAR pixel is therefor

provided by:

σ0 = (ks ⋅ |DN|2 – NEBZ) sin(θloc)

During LEOP (Launch and Early Orbit Phase) and periodically during mis-

sions operations, the constellation performs routine collections over areas of

the world that have well characterised isotropic scattering, typically the Ama-

zon Rainforest and The Congo. Beam calibration then provides a measures for

system noise as a function of beam angle which are applied as corrections to

DN values in ICEYE level 1 image products using an ellipsoid model to deter-

mine θloc. σ0 can therefore be directly calculated from the image product by:

σ0 = ks ⋅ |DNcorrected|2

Where DNcorrected is the digital number in the GRD product which has under-

gone beam calibration correction with respect to incidence angle.

The process for performing beam calibration and using the image DN to cal-

culate radar cross section is detailed in [4]. Table 3 provides calculated worst

case NESZ values for each of its current satellites.

NOISE EQUIVALENT SIGMA-ZERO (DB M2/M2). WORST CASE

ICEYE-X2 -17.0

ICEYE-X4 -19.4

ICEYE-X5 -17.2

Table 3. Noise equivalent sigma-zero values. 35º incidence angle and

300MHz Bandwidth is assumed.


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4 .2 .2 R ADIOMETRIC ACCUR ACYAbsolute Radiometric Accuracy is the RMS error between the measured and

the true RCS at different locations within one scene and also over time. The

absolute radiometric accuracy for the products (including all errors from cal-

ibration devices and processing) derived during the commissioning phases is

<2dB.

Relative Radiometric Accuracy is the standard deviation of the radiometric

error of known targets within one data take. Contributions come from the

antenna pattern, the pointing knowledge of the antenna pattern and drifts of

the instrument during operation. The relative radiometric accuracy estimate

is <1dB .

4 .2 .3 GEOLOCAT ION ACCUR ACYGolocation accuracy is the error associated with the location of a scattering

object within a pixel in a SAR image compared to the object’s true location.

Errors in geolocation accuracy are primarily due to the precision with which

the satellite’s location is known and is related to the precision that the satel-

lite’s orbit can be tracked.

ICEYE predicts its orbits using GPS acquisitions prior to an imaging opera-

tion. These are downloaded with the raw image data and refined during the

processing step.

To validate the geolocation accuracy of SAR products, corner reflectors, sit-

uated at calibration sites around the world are used. Each corner reflector’s

location is precisely known in 3D space. The measured location of the corner

reflectors is compared to the known location to provide a 90% probable circu-

lar error (CEP90). Results of ICEYE geospatial accuracy measurements can be

seen in table 4


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CEP90

PSLR (DB) (THEORY -13.2)

ISLR (DB) (THEORY -5.03)

ICEYE-X2 9m -13.39±0.6 -4.44±0.31

ICEYE-X4 5.7m -13.51±1.95 -4.47±0.88

ICEYE-X5 6.6m -13.65±1.98 -4.45±0.87

Table 4. Point target geolocation accuracy and sidelobe characteristics

4 .2 .4 FOCUSING CAL IBR AT IONCalibration of the SAR image formation processor’s focussing ability is also

performed using calibration target targets situated at ground truthed sites.

Corner reflectors are used as they act as point targets within a pixel. The point

target’s impulse response function can then be measured and compared to

the theoretical best performance. Degradation of focusing manifests itself in

raised sidelobe levels and so these are provided as a measure of performance.

Table # provides the mean peak sidelobe ratio of the satellites measured

during December 2019 and January 2020. The table also provides the mea-

sured integrated sidelobe ratio.


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5 . P r o d u C T s P e C I f I C a T I o n s

5 . 1 S T A N D A R D I C E Y E P R O D U C T S

Standard ICEYE products can be differentiated into two major product

groups: Basic Image Products (geo-referenced slant range complex and ground

range detected scenes) and Geocoded Image Products.

Basic Georeferenced Image Products are satellite path oriented datasets. They

correspond to the Committee on Earth Observation Satellites (CEOS) Level 1b

quality and can be ordered either from archive (previously collected imagery)

or as future acquisitions by contacting our ICEYE Customer Success Special-

ists. Geocoded Image Products are geo-coded and radiometrically corrected

and correspond to CEOS Level 2 quality imagery.

5 . 2 I C E Y E I M A G I N G M O D E S

ICEYE satellites can collect SAR images in several imaging modes. The

available products currently consist of modes called ‘STRIPMAP’ and ‘SPOT-

LIGHT’. All imaging beam modes are available in both right- and left-looking

configurations. In the next section these modes and their radiometric and

geometric characteristics will be described.

5 .2 .1 STRIPMAP IMAGING MODEIn Stripmap mode, the ground swath is illuminated with a continuous

sequence of pulses while the antenna beam is fixed in elevation and azimuth.

This results in an image strip with a continuous image quality in the flight

direction. In order to achieve a consistent ground range resolution that

matches the azimuth resolution, the transmitted pulse bandwidth is tuned

specifically for each collection and depends on the incidence angle.


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Figure 3. Schematics of Stripmap SAR imaging mode

Azimuth resolution in Stripmap mode is largely dependent on the length of

the SAR antenna. ICEYE standard Stripmap products have a ground resolu-

tion of 3m in range and azimuth and cover an area of 30km (range) by 50km

(azimuth). The stripmap length (azimuth) can be tailored to a user’s needs up

to 300km in increments of 50km.

5 .2 .2 STRIPMAP HIGH IMAGING MODEThe standard Stripmap mode adjusts the transmitted pulse bandwidth to

always achieve a ground range resolution of 3m. In some cases, a user may

require a finer range resolution. For this reason the Stripmap High mode is

being introduced. In this mode the transmitted pulse bandwidth is set to be

the maximum of 300MHz. This provides a slant range resolution of 0.5m and

an azimuth resolution of 2.5 to 3m depending on incidence angle. The prod-

uct is available as a slant plane complex image, for precise target analysis and

also in the ground plane. For convenience, the ground range product is multi

looked in range and azimuth to provide a standard 3mx3m with improved

speckle reduction.

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5 .2 .3 SPOTL IGHT IMAGING MODEIn Spotlight mode, the radar beam is constantly steered towards an aim point

on the ground. This increases the illumination time, resulting in an increased

synthetic aperture, and therefore, better azimuth resolution compared to a

continuous stripmap mode.

Figure 4. Schematics of Spotlight SAR imaging mode

The standard Spotlight mode uses a 300MHz transmitted pulse bandwidth

to provide a slant plane image that has a resolution of 0.5m (range) by 0.5m

(azimuth). This product is translated into a ground plane image that extends

5kmx5km with a ground resolution (after multi looking) of 1mx1m.

5 .2 .4 SPOTL IGHT HIGH IMAGING MODEDue to ICEYE’s small satellite agility, they are able to point forwards and

backwards towards a target area by a more-than-conventional amount. This

allows Spotlight Modes to be achieved over an extended Synthetic aper-

ture length to provide a slant plane image with a resolution of 0.5m (range)

by 0.25m (azimuth). This product is also available in the ground plane as a

1mx1m resolution image with an area of 5kmx5km but due to multi-looking,

speckle noise is significantly reduced.

The summary of ICEYE imaging modes are gathered in Table 5.


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PARAMETER STRIPMAPSTRIPMAP HIGH SPOTLIGHT

SPOTLIGHT HIGH

Nominal swath width 30 km 30 km 5 km 5 km

Nominal product length 50 km 50 km 5 km 5 km

Incidence angle [scene centre] 15-30° 15-30° 20-35° 20-35°

NESZ [dBm2/m2] <- 19 <- 17 <-17 <-17

AASR & RASR <- 19 <- 19 <-21 <-21

Slant range resolution [m] 0.5 -1.5 0.5 0.5 0.5

Slant azimuth resolution [m] 2.5 - 3.0 2.5 - 3.0 0.5 0.25

Slant range spacing [m] 0.4-1.3 0.4 0.4 0.4

Slant azimuth spacing [m] 1.4 - 1.7 1.4 - 1.7 0.3 0.15

Ground range resolution 3.0 3.0 1.0 1.0

Ground azimuth resolution 3.0 3.0 1.0 1.0

Ground range spacing 2.5 2.5 0.5 0.5

Ground azimuth spacing 2.5 2.5 0.5 0.5

Looks 1-3(ra),1-4(az) 1-3(ra),1-4(az) 2(az) 4(az)

ESA Copernicus Contributing

Mission (CCM) Resolution Class [6]

VHR-2 VHR-2 VHR-1 VHR-1

Polarization VV VV VV VV

Table 5. ICEYE imaging modes summary


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5 . 3 I C E Y E D A T A P R O D U C T S F O R M A T S

A basic ICEYE product is represented by a set of SAR image binary data along

with the corresponding image annotation metadata, delivered as a singular

product package. Products are characterized by the payload configuration

(such as imaging mode and look direction) used by the respective satellite, as

well as the level of processing that has been applied to the SAR scene. With

respect to the data geometric projection and representation, Basic Image

Products are differentiated into two primary product types, Single Look

Complex (SLC) and Ground Range Detected (GRD).

5 .3 .1 LEVEL-1 SINGLE LOOK COMPLEX (SLC) PRODUCTSSingle Look Complex (SLC) products are basic single look products of the

focused SAR signal. Scenes are stored in the satellite’s native image acquisi-

tion geometry which is the slant-range-by-azimuth imaging plane and with

zero-Doppler SAR coordinates. The pixels are spaced equidistant in azimuth

(according to the inverse of the pulse repetition frequency) and in slant range

(according to the range sampling frequency). Each image pixel is represented

by a complex magnitude value (with in-phase I and quadrature Q components)

and therefore, contains both amplitude and phase information. Each image

pixel is processed to zero Doppler coordinates in the range direction, i.e. per-

pendicular to the flight track.

The SLC products are suitable for applications that rely on phase informa-

tion or require a finer degree of scene understanding provided by a finer

resolution. There are no radiometric artefacts induced by spatial resampling

or geocoding, and the product can be easily orthorectified using both com-

mercial and free software tools such as European’s Space Agency’s Sentinel

Application Platform (ESA SNAP S1TBX). The SLC product is particularly use-

ful for those consumer groups that require interferometric collections or wish

to exploit ground changes through Coherent Change Detection (CCD). The

product is primarily intended for scientific research and development work,

coherent analysis and for organisations with advanced SAR expertise.


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5 .3 .2 LEVEL-1 GROUND R ANGE DE TECTED (GRD) PRODUCTSGround Range Detected (GRD) products represent focused SAR data that has

been detected, multi-look processed and projected to the ground range using

an Earth ellipsoid model. The image coordinates are oriented along the flight

direction and along the ground range. The pixel spacing is equidistant in

azimuth and in ground range. Ground range coordinates are taken from the

slant range coordinates and then projected onto the ellipsoid of the Earth.

For the slant to ground range projection, the WGS84 ellipsoid and a scene-av-

eraged value of terrain height is used and is annotated in the metadata. Pixel

values represent detected magnitude. Phase information is lost. The resulting

product has approximately square spatial resolution and square pixel spacing

with reduced speckle due to the multi-look processing.

An advantage of this product is that no image rotation to a map coordinate

system has been performed and interpolation artefacts are thus avoided. This

product is useful, if geocoding or orthorectification is to be applied by the

customer, or for applications where geocoding is not required. Each image

contains Ground Control Points (GCPs) and rational polynomial coefficients

(RPCs) in order to help a user perform image rectification using industry

standard tools such as QGIS.

This product is particularly useful in cases when stack processing is required,

e.g. followed by change detection. Once a change-detection product is gener-

ated in the satellite path geometry, it can be orthorectified accordingly using

specialized SAR software (e.g., ESA SNAP S1TBX).

Figure 5 shows the mapping from slant range to ground range for ICEYE

Level 1 products.


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Figure 5. Slant range and ground range image geometry


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(a) (b)

Figure 6. ICEYE X2 scene acquired over Gdansk on May 6th, 2019, basic (sat-

ellite path oriented) products: (a) - SLC product, (b) - GRD product.

Figure 7. Ellipsoid Corrected Product Mapping


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5 .3 .3 LEVEL 2 - GEOCODED PRODUCTSICEYE currently provides a Level 2 product that is geocoded called Ellipsoid

Corrected. This product is a multi-looked, detected product which has been

resampled and projected onto a reference ellipsoid with a mean scene centre

altitude being applied. The product is provided in a Universal Transverse Mer-

cator (UTM) map projection. No terrain correction is performed and there is

no geometric correction applied using a Digital Elevation Model (DEM). This

product is ideally suited for mapping applications and can easily be draped

over a DEM, map or external image product using the encoded metadata.

Pixel accuracy for this product will therefore be a function of the DEM used.

5 . 4 I C E Y E D A T A F O R M A T

ICEYE data are stored and delivered in HDF5 files (SLC data) and GeoTiff files

(GRD data and Geocoded products). HDF5 format is particularly suitable for

storing binary complex SAR data channels along with annotated metadata.

On the other hand, GeoTiff images are readily readable by common GIS soft-

ware tools. Additionally, both SLC and GRD products are accompanied by

xml-files containing metadata, thus enabling quick screening of products

without the use of specialized software.

Detailed description of storage format for SLC data is given in ICEYE Basic

Product Format Specification Document available from ICEYE website. Geo-

referenced ICEYE products are readable using specialized SAR software (e.g.,

ESA SNAP - S1TBX) where product orthorectification and further processing

can be performed.

SLC GRD EC QUICKLOOK SIZE (GB)

Stripmap HDF5,XML GeoTiff,XML GeoTiff,XML PNG, KML 0.9-2.8

Stripmap High HDF5,XML GeoTiff,XML GeoTiff,XML PNG, KML 2.8

Spotlight HDF5,XML GeoTiff,XML GeoTiff,XML PNG, KML 0.6

Spotlight High HDF5,XML GeoTiff,XML GeoTiff,XML PNG, KML 2.8

Table 6. Product file formats and sizes


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6 . s a r P r o d u C T o r d e r I n g

6 . 1 I N T R O D U C T I O N T O S A R P R O D U C T O R D E R S

There are two categories of imaging available from ICEYE at this time, with

their own order and delivery process: 1) active new tasking of SAR imagery

and 2) archive SAR images.

ICEYE offers timely and reliable SAR satellite imaging around the world. The

section will describe how to order new tasking, or archive SAR imagery.

1) New image tasking orders consist of acquiring new SAR satellite imag-

ery in accordance with the Customer’s image order details (AOI, timing,

acquisition parameters). New image tasking order flow is described in section

2.2. It is important to note that each frame that is approved for acquisition

counts towards the use of the Customer’s account and purchased New image

tasking count.

2) Archive images from ICEYE satellites are available for Customer down-

load as individual frames. The Archive image order flow is described in

section 2.3. Each ordered Archive image counts towards the use of the Cus-

tomer’s account and purchased Archive image count.

6 . 2 N E W I M A G E T A S K I N G O R D E R F L O W



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6 .2 .1 ORDER SUBMISSIONNew image orders are to be submitted via email. To order, please fill out the

Imagery Order Form with your contact information, details about your Area

of Interest (AOI) and the associated order parameters. Along with the Order

Form, the preferred option to submit your Area of Interest is a kml/kmz file

containing the centre coordinates of your AOI. Once filled, please return your

Order Form and your kml/kmz file to the email address [email protected].

The named recipients for that order will be notified via email once the order is

received by the ICEYE Customer Success Team.

6 .2 .2 EVENT PL ANNING AND ACQUISI T ION SCENARIOOnce the order has been received, the assigned Customer Success Specialist

(CSS) will treat the order within 24h using the provided imaging parameters

to find the best possible option for image acquisition. The CSS, then, prepares

an acquisition scenario for the images to be sent to the customer for approval.

The image acquisition scenario includes basic information about the expected

SAR frame such as: acquisition date and time, look side of the sensor, the orbit

direction and the area coverage . In cases where the Customer’s AOI can’t be

covered with a single image in the expected timeline, an acquisition scenario

consisting of multiple frames will be planned. It is worth noting that multiple

frames of the same AOI each count towards the use of the Customer’s account

and purchased New image tasking count.

The acquisition scenario is to be approved within 24h from the moment it was

received from the ICEYE CSS. During these 24h, the capacities listed in the

acquisition scenario are reserved exclusively for the customer. After 24h, the

collections will not be cancelled but ICEYE reserves the right to enable those

capacities for other potential customers.

If the Customer approves the acquisition scenario, the acquisition event (or

events) will be scheduled for collection.



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6 .2 .3 IMAGE TASK ING , SATELL I TE IMAGING AND IMAGE DOWNL INK INGThe ICEYE satellite takes images according to the tasked events. Once an indi-

vidual frame is taken, it will be downlinked to the ground station as planned

. Once it has been downlinked, it will be delivered to the processing center

where the data will be decoded and processed.

6 .2 .4 QUAL I T Y CONTROL The processed data will be assessed during the Quality Control process. An

ICEYE image analyst will verify that the frame contains the customer’s target

location, that it complies to the product specifications and that it does not

contain any disqualifying ambiguities.

Currently, ICEYE does not provide certificates for individual frames that

guarantee specific parameters. In cases where a frame does not pass the qual-

ity assurance process, the Customer is notified and a course of action is agreed

with the Customer.

6 .2 .5 IMAGE DEL IVERY TO CUSTOMERThe frames are to be delivered to customers via an assigned SFTP server,

within 24h after the data was acquired. Following the initial on-boarding, you

will receive instructions from the Customer Success team on accessing your

organisation’s SFTP server, where individual frames and their preview images

are added. Through the SFTP server, you will have access to download all of

the frames that your organisation has ordered and which have been imaged.

You will receive a notification every time a new frame has been delivered and

is ready for your download.

6 .2 .6 OFF -NOMINAL SCENARIOS Off-nominal scenarios are unexpected situations that might occur excep-

tionally. Such situations can be identified when the image wasn’t acquired or

a frame doesn’t pass the quality control procedure. In this case, the Customer

Success Team will immediately inform the customer and will propose a new

acquisition scenario that can possibly match the initial request. If the cus-

tomer approves the new acquisition scenario, the acquisition will be scheduled

with no extra charge.



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6 . 3 O R D E R F L O W F O R A R C H I V E I M A G E S

6 .3 .1 ORDER SUBMISSIONTo order Archive imagery, the Customer needs to fill out the Order form

and generate a kml/kmz file of the AOI. The Order Form is to be sent along

with the AOI via email to [email protected]. Within 1 business day the

ICEYE Customer Success Team will then query the ICEYE Archive to identify

any products that match the Customer’s order. If the AOI requested by the

Customer matches completely or partially any of the images in the ICEYE

Archive, the order will be submitted to the system. The order is confirmed by

email to the Customer with the matching images and who will then be invited

to select those products that they require.

In cases where there are no matches with the ICEYE Archive, a Customer Suc-

cess Specialist will notify the Customer, and suggest a new acquisition which

the Customer can either accept or decline.



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PARAMETER ARCHIVE HOLDINGS

Swath length 50-60 km

Incidence angle 10 - 35 degrees

PRF 4000 - 6000 Hz

Swath width 5 - 40 km

Pulse duty cycle 20%

Pulse bandwidth 100 - 300 MHz

Ground Range Resolution 0.5 - 3 meters

Ground Azimuth Resolution 0.5 - 3 meters

Table 7. ICEYE Image Archive range of data properties

6 .3 .2 ORDER PROCESSINGThe requested image(s) are taken from the Archive and a quality assessment

is performed. The Customer Success Specialist checks the format of the final

product requested by the Customer and prepares the image for the delivery.

In case the order contains multiple archive images to be delivered, all the final

product files are delivered in bulk.



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6 . 4 O R D E R C A N C E L L A T I O N

In order to support your evolving business requirements, ICEYE supports a

user friendly order cancellation policy.

STANDARD NEW TASK INGNew tasking image orders accepted by the Customer and tasked by ICEYE’s

Customer Success Team may be cancelled or rescheduled within twenty four

(24) hours after the confirmation of the Acquisition Scenario without incur-

ring any additional costs, when submitting and confirming the order 72

hours in advance of the proposed data collection time.

Cancellation policy conditions are presented in the table below:

CANCELLATION REQUEST TIME (HOURS)

ADDITIONAL CONDITION

CANCELLATION CHARGE

within 24h after the

confirmation of the

Acquisition Scenario

order submitted >72h

before the image

acquisition

free of charge

more than 72h prior

to acquisition

N/A free of charge

72 - 48h prior to

acquisition

N/A 10% of the image

value

48 - 24h prior to

acquisition

N/A 20% of the image

value

less than 24h prior to

acquisition

order submitted >24h

before the image

acquisition

100% of the image

value



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SHORT TERM NEW TASK INGImages ordered and confirmed less than 24h in advance from the acquisition

cannot be canceled without a financial charge of 100% of the image value.

ARCHIVE IMAGE ORDERSArchive image orders can’t be canceled after the order has been submitted, as

the Customer has the opportunity to evaluate the image specifications before

order.

ORDER CANCELL AT ION PROCESSTo cancel an order, the customer simply sends an email to [email protected]

specifying the order ID that is canceled. If the order contains multiple events,

the customer can specify the events that are canceled. If no particular event is

specified in the cancellation request, all the events that are still not acquired

are canceled.

ICEYE Customer Success Team will apply the cancellation policy to each event

included in the order separately and will notify the customer whether any fees

incurred.

6 . 5 I N V O I C I N G

Invoicing process in ICEYE is built on one of the following payment terms:

f Net 30 - meaning the invoice for the delivered products have to be paid

by the Customer during 30 days after the invoice has been sent

f Prepayment - meaning that the Customer will be invoiced after the

signature of the contract or purchase order. When the prepayment

has been paid, the Customer is entitled to place orders and receive the

amount of data equal to the one covered by the prepayment.

ICEYE Accounting will send invoices during the first week of the month for

all the products delivered to the Customer within the previous month. The

monthly invoice will not include the products that have been ordered but have

not yet been delivered to the Customer. If no products have been shipped to

the Customer during the previous month, invoice will not be extended.


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7 . s u P P o r T

7 . 1 C U S T O M E R S U C C E S S T E A M

Customer Success (CS) team is a department of ICEYE in charge of the order

processing and support of the Customer Organizations. Customer Success

staff who interacts directly with the customer are called Customer Success

Specialists. The scope of responsibilities of the CS Specialist are:

f Customer onboarding and training;

f Customer order management

f Receiving order

f Confirming order

f Processing order

f Running products through the Quality Control Team

f Delivering order

f Customer Communications regarding any issues within the frame-

work of the current contract;

f Customer Feedback management;

f Improvement of the existing processes in order to improve overall cus-

tomer experience.

7.1 .1 WORK ING HOURSThe Customer Success team is available from 7:30 - 15:00 UTC (summer) and

08:30 - 16:00 UTC (Winter) with additional extended hours being introduced

over the next quarter.

7.1 . 2 CONTACT INFORMAT IONThe customer can reach out to the Customer Success team via email

[email protected].


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8 . r e f e r e n C e s

[1] “Echoes in Space, Introduction to Radar Remote Sensing”, ESA EO College, online train-

ing course 2019, https://eo-college.org/courses/echoes-in-space/

[2] “ICEYE SAR Videos Published: Technical Insights and Highlights”, Internet post, Mar

10 2020, https://www.iceye.com/satellite-data/blog/iceye-sar-videos-published-technical-

insights-and-highlights

[3] “New Benchmark in Imaging from SAR Microsatellites: ICEYE Presents 25cm

Resolution”, Internet post, Apr 2 2020,https://www.iceye.com/satellite-data/blog/

new-benchmark-in-imaging-from-sar-microsatellites-iceye-presents-25-cm-azimuth-reso-

lution

[4] “ICEYE Level 1 Product Format Specification Document”, https://www.iceye.com/hubfs/

Downloadables/ICEYE-Level-1-Product-Specs-2020a.pdf

[5] Copernicus Space Component Data Access Portfolio: Data Warehouse 2014 - 2020. resolu-

tion classes for EO SAR Image products

www.ICEYE.com

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