RAW2CHIP

Description

RAW2CHIP performs automatic chip extraction from a raw image and ground control point (GCP) segment to a chip database. It creates chips around each of the GCPs.

Parameters

Name	Type	Caption	Length	Value range
FILE *	String	Input file name	1 - 192	1 - 3
DBIC *	Integer	Input raster channels	1 - 3
DBGC	Integer	Input GCP segment	0 - 1
BACKVAL	Integer	Background data value	0 - 3
MMSEG	Integer	Math model segment	0 - 1
RESAMPLE	String	Resampling mode	0 - 6	NEAREST, BILINEAR, CUBIC Default: CUBIC
CHIPFILE *	String	Chip database file name	1 - 192
CHIPSENS	String	Sensor origin of chips	0 - 16
CHIPDATE	String	Chip acquisition date	0 - 21
CHIPSIZE	Integer	Size of chips (pixel, line)	0 - 2	64,64 - 256,256 Default: 64,64

* Required parameter

Parameter descriptions

FILE

Specifies the PCIDSK file that contains the raw input image for processing.

DBIC

Specifies the input raster channels that contains the Ground Control Points.

DBGC

Specifies the Ground Control Point segment or layer number in the input raw image from which to extract chips.

If empty, this parameter uses the last segment in the input file.

BACKVAL

Specifies the background, or no-data value, of the input file.

If empty, all pixels are considered as valid data. Selected chips contain no background pixels.

In some cases, chips must be rejected; for example, if the center of a chip is located on a background value, or if a chip contains more than 50 percent background value.

MMSEG

Specifies the math model segment or layer that contains a math model (any type) for the input image. This value is used as the approximate position of the image for creating the chips.

If empty, this parameter uses the last math model segment in the input file.

RESAMPLE

Specifies the type of resampling method that is used.

Resampling extracts and interpolates the gray levels from the original pixel locations to corrected locations.

Three resampling modes are supported.

• NEAREST: Nearest-neighbor interpolation identifies the gray level of the pixel closest to the specified input coordinates and assigns that value to the output coordinates.
• BILINEAR: Bilinear Interpolation determines the gray level from the weighted average of the four closest pixels to the specified input coordinates and assigns that value to the output coordinates.
• CUBIC: Cubic Convolution determines the gray level from the weighted average of the 16 closest pixels to the specified input coordinates and assigns that value to the output coordinates.

The default value is CUBIC.

CHIPFILE

Specifies the name of the chip database in which to store extracted chips. If the specified file already exists, new chips are appended to it; otherwise, a new .cdb file is created.

CHIPSENS

Specifies the sensor origin of the newly created chips; for example "Spot".

This is a free-format sensor name that is used elsewhere to identify chips to match with other features. The sensor name is limited to 16 characters.

CHIPDATE

Specifies the acquisition date of the geocoded file.

A regular expression for chip dates (ddmmmyyyy) is acceptable. This information may be used elsewhere to identify chips matching a specific time period.

CHIPSIZE

Specifies the size of each extracted chip, in pixels x lines. The minimum chip size is 64x64; this is the default value. The maximum chip size is 256x256.

Details

RAW2CHIP automatically extracts chips from raw image files containing Ground Control Point (GCP) segments and stores them in a chip database.

The function collects information from the GCPs (XYZ, ID, pixel and line location, and projection system) and the raw image that corresponds to a feature, and outputs to a chip database that contains chips for all the GCPs in the specified segment.

Example

Extract a set of chips from Spotleft.pix with the GCPs stored in segment 3. Save the extracted chips in spot_example.cdb.

EASI> FILE	=	"Spotleft.pix"
EASI> DBIC	=	1
EASI> DBGC	=	3
EASI> BACKVAL	=	0
EASI> MMSEG	=	4
EASI> RESAMPLE	=	"CUBIC"
EASI> CHIPFILE	=	"spot_example.cdb"
EASI> CHIPSENS	=	"SPOT"
EASI> CHIPDATE	=	"31DEC2005"
EASI> CHIPSIZE	=	64, 64

EASI> r RAW2CHIP