PNT2CHIP

Description

PNT2CHIP extracts chips from a geocoded image using a point layer.

Parameters

Name	Type	Caption	Length	Value range
GEOFILE *	String	Geocoded file name	1 - 192
DBIC *	Integer	Input raster channels	1 - 3
BACKVAL	Integer	Background data value in geocoded layer	0 - 3
FILV *	String	Input file containing points	1 - 192
DBVS *	Integer	Input vector segment	1 - 1
FLDNME	String	Field name for Chip IDs	0 - 192	Default: ShapeID
CHIPFILE *	String	Chip database	1 - 192
CHIPSENS	String	Chip sensor type	0 - 16
CHIPDATE	String	Chip acquisition date (ddmmmyyyy)	0 - 21
CHIPSIZE	Integer	Chip size	0 - 2	Default: 64
FILEDEM	String	DEM file name	0 - 192
DBEC	Integer	Elevation channel	0 - 1	1 - Default: 1
BACKELEV	Float	Background value in elevation layer	0 - 1

* Required parameter

Parameter descriptions

GEOFILE

Specifies the name of the geocoded file from which to extract chips.

DBIC

Specifies the input channels in the geocoded file from which to extract chips.

BACKVAL

Optionally specifies the background (NoData) value of the geocoded file. If this parameter is not specified, the BACKVAL value will be set from the NO_DATA_VALUE metadata tag.

All pixels are considered valid values if BACKVAL is not set.

FILV

Specifies the file that contains the points for which chips will be collected. One chip will be created centered about each point in the point layer.

DBVS

Specifies the vector segment number of the input point layer from FILV.

FLDNME

Specifies a field name in the input vector segment that will be used as Chip IDs - unique identifiers for the generated chips. If no field is specified, ShapeID is used by default.

CHIPFILE

Specifies the name of the chip database to receive the extracted chips.

If the specified database already exists, new chips are appended to it. If it does not already exist, the function creates a new chip database file (.cdb).

CHIPSENS

Optionally specifies the name of the sensor for the geocoded image. This is a free format that can be used later to select appropriate chips.

CHIPDATE

Optionally specifies the acquisition date of the geocoded file.

A regular expression for chip dates (ddmmmyyyy) is acceptable; for example, "01may2012". This parameter may be used later to select chips that match an appropriate time period.

CHIPSIZE

Optionally specifies the size of each extracted chip, in pixels and lines. The default size is 64 x 64.

Because this parameter accepts up to two values, rectangular chips can be extracted. When only one value is provided, square chips result. The maximum size for each side of the square or rectangle in 1024.

FILEDEM

Optionally specifies the DEM file to receive the elevation value of the extracted chip.

When no DEM is provided, the elevation of the chip will be assigned the elevation of the point from which the chip was created.

DBEC

Optionally specifies the channel number in the DEM file (FILEDEM) to provide the height information for each extracted chip.

This parameter is used only if a DEM file (FILEDEM) is specified. If FILEDEM is specified but DBEC is not, the function uses the first channel.

BACKELEV

Optionally specifies the background elevation (NoData) value in the DEM elevation channel. If one of the provided points falls on a pixel with this value, that point is ignored.

If the output DEM file (FILEDEM) is specified and this parameter is not, the BACKELEV value will be set from the NO_DATA_VALUE metadata tag.

All pixels are considered valid elevation values if BACKELEV is not set.

This parameter is used only if an input DEM file is specified.

Details

PNT2CHIP extracts image chips from a geocoded file to a chip database, based on an input point vector layer. The extracted chips are stored in a chip database, which can be used for future image tie-down or automatic geocoding.

The projection of the point vector layer can be different than that of the geocoded file. If the projections are different, the point locations are projected on-the-fly to the projection of the geocoded image.

If background (NoData) values exist in the geocoded image, you must specify this value using the BACKVAL (Background data value in geocoded layer) parameter. Chips with background values are ignored.

You may specify a chip sensor and date for the geocoded file; these values can be used later in automatic geocoding to select chips that match the appropriate information.

PNT2CHIP will assign the vector layer point ShapeID as the image chip ID.

To perform orthorectification in a future process, you must extract the elevation of the chip by specifying a digital elevation model file (FILEDEM) with an elevation channel.

Example

Extract chips about each point in POINTS.PIX and create a new chip database geocodedSourcePPF.cdb.

EASI>geofile = "OSPOTR.PIX"
EASI>dbic= 1
EASI>backval = 0
EASI>filv = "POINTS.PIX"
EASI>dbvs = 4
EASI>fldnme = 
EASI>chipfile = "geocodedSourcePPF.cdb"
EASI>chipsens = "SPOT"
EASI>chipdate = "15Sep1999"
EASI>chipsize = 64
EASI>filedem= "SPOTDEM.PIX"
EASI>dbec = 1
EASI>backelev = 

EASI>run PNT2CHIP