GENFOOTPRINTS

Description

GENFOOTPRINTS processes a collection of geospatial data and produces vector footprints representing the extents for each file.

Parameters

genfootprints(mfile, filo)

Name	Type	Caption	Length	Value range
MFILE *	str	Input file name, folder, or text file	1 -
FILO *	str	Output file name	1 -

* Required parameter

Parameter descriptions

MFILE

The name of an image file, a folder, or a text file of images to process. If necessary, you can use a wildcard (*) in the string.

All of the source images must be compatible with one another; that is, they must have the same projection, channel structure, bit depth, and approximately the same resolution.

You can specify any of the following options for this parameter:

A specific file name or folder and file name; for example, "irvine.pix" or "C:\data\irvine.pix"
A specific file name pattern or all files in a folder; for example, "C:\data\*.pix" or "C:\data"
An existing text file of references to multiple files with, optionally, different parameter settings per file; for example, "C:\list.txt"

If you reference a text file, the following general rules apply:

The file containing multiple files and different parameter values must have a .txt file name extension.
Each set of parameters must be listed on its own line in the given order.
String parameters must be start and end with quotation marks.
Do not specify numeric parameters in quotation marks.
A quotation mark preceded by a backslash is used as part of the string; for example, ab\"c is used as: ab"c.
Any comments in the text file must have an exclamation mark (!) as the first character of the line.
Use semicolons to delimit the parameters.
When you do not want to specify a value, leave the position between the semicolons empty (";;"). Alternatively, if there are no remaining parameters to specify on the end of a line, you can leave it blank.
Parameters in a text file may or may not be specified in the function:
- When a parameter is specified in the function and in the text file, the value in the text file is used.
- When a parameter is not specified in the text file, the parameter can be specified in the function.

FILO

The name of the output file to which to write the footprints. The output file contains one vector segment of all polygon footprints for the input files.

The file must not already exist; otherwise, processing stops, and an error message is displayed.

The following two attributes are added to the vector layer created in the footprints file:

FileName: contains the file name of source image
ImageID: contains the basename of the source image

Details

GENFOOTPRINTS determines the four corners of an input image based on the file georeferencing. The four corners are used to generate a polygon, which is essentially the footprint of the file, for each input image. The output polygons are stored in one vector segment in the output file.

For GENFOOTPRINTS to generate footprints, the input data must be reprojectable to LONG/LAT.

Note: PIXEL georeferencing is not supported.

The output file must not exist already. If so, prcoessing stops, and an error message is displayed.

Example

In this example, GENFOOTPRINTS is run on a set of images to generate polygon footprints of the input data. To determine the area and perimeter statistics for each footprint, you can run VECAREA.

from pci.genfootprints import genfootprints

mfile=	"imagery"	# location of source images
filo=	"footprints.pix"	# output file name

genfootprints(mfile, filo)

from pci.vecarea import vecarea

file 	= 	"footprints.pix"
dbvs 	= 	[2]

vecarea(file, dbvs)

Environments	PYTHON :: EASI
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