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Area of application

Process flowsheets

Detailed specifications

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Detailed specifications

Import / Export software tool
Viewer software tool
Geocoding Processor
Interferometric Processor
Stereo Processor

Supported formats.

Currently Import / Export tool supports import of following data types:
binary data;
graphical formats: TIFF, Geo TIFF, JPEG, BMP;
international SAR data format CEOS;
special format for ENVISAT SAR data;
special format for Almaz-1 SAR data;
digital terrain data formats: GTOPO30, USGS DEM.
Data can be exported from internal format to following formats:
raw binary;
graphical formats: TIFF, Geo TIFF, JPEG, BMP;
digital terrain data format USGS DEM.
Tabulated information on import options into RDP format from external sources and export options of RDP files to other formats is represented below.

Information on import options into RDP format from external sources and export options of RDP files to other formats

File format
Import
Export
Almaz-1
+
-
CEOS SIR-C/X
+
-
CEOS ERS UK-PAF
+
-
CEOS ERS I-PAF
+
-
CEOS Radarsat SDPF
+
-
ENVISAT
+
-
TIFF
+
+
Binary data
+
+
Windows Bitmap
+
+
GTOPO30
+
-
JPEG
+
+
USGS
+
+
Geo Tiff
+
+

Viewer software tool

Data Types
Radar internal RDP format supports a number of various data types. The supported types could be divided into two categories: scalar and complex types. For Scalar data each pixel corresponds to just one defined data type (integer or float point).

Supported Scalar Data Types

Data type
Notation
Range of values
Unsigned integer 8 bit
U8
0 to 255
Unsigned integer 16 bit
U16
0 to 65 535
Unsigned integer 32 bit
U32
0 to 4 294 967 295
Signed integer 8 bit
S8
-128 to 127
Signed integer 16 bit
S16
-32 768 to 32 767
Signed integer 32 bit
S32
-2 147 483 648 to 2 147 483 647
With float point 32 bit
F32
.
With float point 64bit
F64
.

NOTE: the notation used in above outlined table is intended for the short indication of corresponding data types. Notation for the complex data types is similar to one for the scalar types but the letter C is added in front of it. For instance, CF32 is the complex type that has two components of F32 type.

If RDP files contain the scalar type data, they are called as scalar files. For the Complex data each pixel corresponds to two numbers of one scalar type. The first of these numbers is identified as a real part, and second one as an image part of complex data. Following by physical content of the complex data, acquired by the remote sensing radar, they could be presented as two derived components: amplitude (module of complex number) and phase (argument of complex number). Corresponding complex type is supported for each scalar type. The RDP files, which containing the data of complex type, are identified as the complex files.
Commonly, the data of radar remote sensing are represented as a gray halftone rasters. Each magnitude range of data values corresponds to some tone of gray color. The relations between tones and data values are defined of the palette and special transformation table (look-up table).
The term Look-Up Table (LUT) is widely used in the image processing applications. For instance, if we need to display the values from 0 up to 160 via 16 color levels, the simplest way will be to divide whole values range 0 - 160 onto ten equal portions and assign to each portion its own color level from 0 up to 16. The result of this operation is summarized in the table below:

0..10
11..20
21..30
31..40
.......
131..140
141..150
151..160
0
1
2
3
13
14
15

It shows how values of pixels will be changed after their brightness transformation. It clearly seen that this transformation is linear. The linear transformation type is the most simple but sometimes the nonlinear transform type is applied.

In Viewer software tool you can
define your own transformation table, linear and distinguished from linear;
change the palette;
assign the combination of brightness values from different three files (one file on each color RGB channel) to pixels in the Viewer window. This option provides a suitable way to perform the multi frequency and multi polarization data from remote sensing sensors.
define the different methods of histogram stretching, the interesting channels for multi-spectral images, visualizing mode for radar complex (presented as the real and imagery parts) images, select the interesting image area and decimation order.

The following ways of the histogram stretching is available currently:
under specified dispersion. It means that only pixels with values not exceeded the range of m+N*dispersion, are shown without suppression. Here m – is an average value and N – is a user’s assigned number;
under two dispersion. This is particular case of previous step, where N=2;
default stretching. 90% of all pixels in vicinity of average value are displayed without suppression;
without stretching, The histogram doesn't change;
minimum-maximum stretching. User should assign the desired minimum and maximum values for which histogram will be stretched.
The histogram stretching doesn't change values in file, but affects on look-up table only when the image opens.

Geocoding Processor

Geo Processor software provides:
Input SAR image transformation from antenna coordinate system (ACS) to ground reference coordinate system (GFS) - georeferensing;
Input SAR image transformation from ACS or GFS to user given cartographic projection without using of Digital Elevation Model (DEM) - geocoding;
Input SAR image transformation from ACS or GFS to user given cartographic projection without using of DEM – orthorectification.

Geo Processor software consists of next modules:
Georeferensing, geocoding and orthorectification;
SAR platform modeling with using of ephemeris data;
Coordinate system transformation from orbital (inertial) to Greenwich and back;
Entering and controlling input data;
Adjusting of input ephemeris data using ground control points parameters.

Next local tasks are solved:
Recalculating SAR platform motion parameters from one coordinate system to another;
Platform motion parameters prognosis;
Platform motion parameters approximation;
Platform motion parameters correction;
Calculation ground to slant range polynomial coefficients;
Solving of geocoding equations.

Geo Processor software compatible with next data formats:
Geocoding and orthorectification – RADARSAT (SGF), ERS-1/2 (SLC, SGF);
Georeferencing – ERS-1/2 (SLC).

Used coordinate systems:
Absolute geocentric equatorial (inertial) coordinate system (OXYZ)
Source point – Earth center.
Axe X – directed to point of equinox;
Axe Z – coincides with Earth rotation axe;
Axe Y- complements the system to right hand.
Greenwich coordinate system (Oxyz)
Source point – Earth center. System rotates with Earth.
Axe x – coincides with intersection of equatorial plane with plane of Greenwich meridian;
Axe z - coincides with Earth rotation axe;
Axe y - complements the system to right hand.
The integration of differential platform motion equations and calculations of ground point geodetic coordinates are realized.
Velocity baricentric coordinate system (OXcYcZc)
Source point – mass center of platform.
Axe Xc – directed to platform velocity vector;
Axe Yc - perpendicular of orbital plane and parallel to kinetic moment vector С (square integral).
Axe Zc - complements the system to right hand.
Used for geocoding equations solving.

Interferometric Processor

Import of data and auxiliary information
- Data file reading.
- Parameters reading from CEOS format.
- Processing parameters formation.
Image coregistration
- Search of identical points on the master and slave images.
- Transformation of slave image to the master image geometry.
- Overlapping area determination.
Orbit correction for master image with help of ground control points.
Baseline correction.
Preliminary processing
- Subset selection.
- Multilook parameters selection.
Interferogram and coherence calculation
- Calculation of flattening coefficients for range and azimuth directions:
1) The choice of a mode "Precise" means calculation of coefficients of compensation for each image pixel individually. Thus time for realization of operation is increased.
2) In a mode "Fast" the coefficients of compensation calculated for the central column and the central line of a picture are used.
3) In a mode "No flattening" flat Earth phase correction operation will not be executed.
- Complex multiplication of master and transformed slave images.
Interferogram filtration
- Local estimation of phase noise parameters.
- Calculation of filtered phase values.
The following filters are accessible to use:
1) Average filter.
2) Spectral adaptive filter.
Phase unwrapping
- Conversion of wrapped [0, 2Pi] phase values to absolute ones.
The following methods are accessible to use:
1) Unweighted phase unwrapping.
2) Picard iteration method.
3) Conjugate gradients method.
4) Growing pixels method.
Absolute phase to relative height recalculation
Absolute phase to absolute height recalculation
- Transformation of absolute phase to height.
- Georeferencing of height matrix.
Geocoding of height matrix
- Geocoding of height matrix.
- Orthorectification of height matrix.

Stereo Processor

Import and auxiliary data handling
- Reading of SAR data files.
- Reading of CEOS data files.
- Generation of parameter’s set needed for processing.
Georeferencing (for slant range data only)
- Transformation from slant range to ground range.
- Re-sampling to grid with same X and Y axes.
Co-registration of images
- Rotation and re-sampling of Slave image relatively to Master one with use of Tie Points:
1) Coregistration on two tie points;
2) Coregistration on an ephemeris.
- Selection of overlapping areas on both images.
Pre-processing
- Subset of interested areas.
- Low-pass filtering.
Parallaxes to heights conversion rate
- Calculation of coefficients for parallaxes-to-heights conversion from CEOS ephemeris.
- Calculation of coefficients for heights conversion with use of Tie Points.
Stereo matching
- Generation of radar parallaxes matrix.
- Generation of correlation functions matrix.
Smoothing
- Low-pass filtering of parallaxes matrix.
Relief heights generation
- Parallaxes to reference heights conversion.
- Absolute heights calculation from GCP.
- Absolute heights calculation from ephemeris data.
Transformation to reference projection
- Geocoding of heights matrix.
- Orthorectification of heights matrix.

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Last modified: 06.12.2018© Racurs, 2004-2018