<< Click to Display Table of Contents >> Navigation:  Help Content > General Tools > Sample Selections > General Tools - Sample Selection - Sample Selection (Geographic Data)

Purpose

 

A spatial subset of the data can be performed either manually or automatically. Manual selection can be performed specifying the area of interest either with its corner co-ordinates or using a vector file, while the automatic process is performed by extracting a common area of an image series.

 

Technical Note

 

In case the processing has to be executed on a portion of the original data, the data resize must be executed using this tool instead of the ENVI own functionality (i.e. Basic Tools>Resize Data). Indeed the image subset has to keep all the information contained in the original data, otherwise any further process - executed within SARscape - would fail.

 

In case the input data are not geocoded, the sample area can be specified either in raster (column/row) or in cartographic co-ordinates. If the input data are geocoded the sample area can be specified either as file co-ordinates or in any supported cartographic system. This functionality also supports an "Input file list", which is made of images referred to different cartographic systems and/or in slant geometry.

 

In case of an automatic selection, the extracted data have all the same number of rows and columns. Data with different grid size are not supported.

 

Input Files

 

Input File list

Input file name(s) of the data to be processed. This file is mandatory.

 

Optional Files

 

Area of Interest        

A vector file (.shp) or a Google Earth file (.kml or .kmz) can be entered to specify the area to be processed. In case the area is irregular, the circumscribed rectangular area is considered.

This file is optional.

 

DEM/Cartographic System

 

DEM File        

This file is needed when the sample area is specified in cartographic co-ordinates. Alternatively the Cartographic System (together with the "Reference Height") must be entered. This file is optional.

 

Output Projection

In case that the sample area is entered in cartographic co-ordinates and the Digital Elevation Model is not used, the following parameters are compulsory to define the Cartographic System:  

 

State

Definition of the country or general projection systems.

 

Projection

Definition of the projection system of the selected State. In case that a general projection system is selected in State, the Projection is automatically set.

 

Ellipsoid

Definition of the ellipsoid. This is chosen according to the selected State and Projection.

 

Hemisphere

Definition of the hemisphere. This is chosen according to the selected State and Projection.

 

Zone

Definition of the zone. This is chosen according to the selected State and Projection.

 

Datum Shift Parameters

Definition of the datum shift parameters. These are chosen according to the selected State and Projection.

 

Cartographic Parameters

The reference parameters for some projection systems (e.g. Stereographic, Polar Stereographic, Gnomonic, Mercator, Miller, Albers, etc.) can be set.

 

Parameters - Principal Parameters

 

Make Maximum Common Area

By setting this flag the automatic process to extract the common area of an image series is performed.

 

Common Dummy area        

By setting this flag, pixels with no value (dummy pixels) are not taken into account to define the number of rows and columns in the output files. Moreover dummy pixels in one of the input data are set to dummy in all output files.

 

Geographical Region        

By setting this flag the area to be processed is specified in cartographic co-ordinates or georeferenced vector file (referred to the input DEM or Cartographic system); otherwise file co-ordinates (i.e. slant range geometry) must be entered. Co-ordinate decimal values must be entered using the dot (e.g. 29.30) and not the comma (e.g. 29,30) character.

 

The Northernmost cartographic co-ordinate or the first row file co-ordinate.

 

The Southernmost cartographic co-ordinate or the last row file co-ordinate.

 

The Westernmost cartographic co-ordinate or the first column file co-ordinate.

 

The Easternmost cartographic co-ordinate or the last column file co-ordinate.

 

Parameters - Global

 

It brings to the general section of the Preferences parameters. Any modified value will be used and stored for further processing sessions.

 

Parameters - Cut

 

See the Principal Parameters section for the parameters description.

 

Parameters - Other Parameters

 

It brings to the general section of the Preferences parameters. Any modified value will be used and stored for further processing sessions.

 

Output Files

 

Output File list

Output file name(s) of the extracted data. This file is mandatory.

 

_cut_[input extension]                

Resized data and associated header files (.sml, .hdr).

 

.xml

Xml file containing the geographic co-ordinates of the scene corners.

 

.shp

Shape file and associated header files (.sml, .hdr) containing the image perimeter in geographic co-ordinates.

 

.kml

ASCII file containing the image perimeter in geographic co-ordinates. Double clicking on this file will automatically position the boundaries of the scene into the Google Earth environment.

 

_orb.sml        

Xml file containing the scene orbital parameters. This file is generated only for ASAR_WS products.

 

Details specific to the Units of Measure and Nomenclature of the output products can be found in the Data Format section.

 

General Functions

 

Exec

The processing step is executed.

 

Store Batch        

The processing step is stored in the batch list. The Batch Browser button allows to load the batch processing list.

 

Close        

The window will be closed.

 

Help

Specific help document section.

 

 

Specific Function(s)

 

None.

 

See Also

 

Task, SARscapeBatch object, SARscapeBatch script example

 

References

 

None.