Chip Database Generation module

Description

The Chip Database Generation module generates a chip database from input image tiles.

Parameters

Name	Caption
Input Folder	Input scene folder
Output Folder	Output folder
Overwrite Results	Overwrite existing results
Include Subfolders	Include subfolders in search
Send Email	Email notification settings
DEM Source	DEM tile source
Generation Method	Method for creating GCP candidates
Susan Channels	Channels to use with Susan generation method
Distribution Method	Method for distributing GCP candidates
Distribution Amount	Value to determine candidate distribution
Candidate Trials	Number of trials per candidate
Chip Size	Size of the output image chip

Parameter descriptions

Input Folder

The path and name of the folder containing the image tiles in PIX format to process.

Output Folder

The path and name of the folder to which to write the output files.

Overwrite Results

Select this check box to overwrite the existing output files, if any exist. If this check box is left clear, and an output file exists in the relevant folder, the status of the job displays a message informing you of the existence and name of the output file. The message is also written to the event log of the job.

Include Subfolders

Select this check box to include subfolders in the search.

Send Email

If necessary, you can set up CATALYST Enterprise to send an email notification on job start and job completion.

With this check box selected, an email message is sent to each address specified in the Email Addresses box after the job starts and on completion.

You can specify one or more addresses, and each must be separated by a comma or a semi-colon. The email address of the user currently logged in displays by default.

DEM Source

The name of a file or folder containing DEM tiles.

This value may be the name of a single DEM file, the name of a folder containing DEM tiles, or the name of an index.txt file.

If the name of an existing folder is specified, the module reads the folder for a file named index.txt, and a set of DEM raster tiles. The index.txt file lists the DEM files contained in the specified folder and provides information describing each raster tile.

For more information on the format of the index.txt file and specific requirements for the individual DEM tiles, see Format of the DEM index file.

Generation Method

The method to create GCP samples from the source imagery.

You can specify either of the following methods:

Susan: Sample points are generated automatically by using the Susan corner-detection algorithm.
Grid: Sample points are generated automatically by using sample points distributed evenly across the reference image.

Both methods determine how to find the candidate positions in the reference image.

Susan finds the candidates by running a corner-detection algorithm on the image, which looks for corner-like features to use as candidates.
Grid creates candidates in a grid-like pattern. Because this option does not preprocess the image, it tends to be faster, but it also finds fewer matches, because the grid point might fall on a featureless, flat patch somewhere in the image that cannot be matched to anything in the overlapping images.

The default method is Grid.

Susan Channels

The channel or channels from the reference image to use with the Susan method when collecting GCPs. Channel 1 is the default.

When multiple channels are specified, they are averaged together.

Note: You can only use this parameter when the value of Generation Method is Susan.

Distribution Method

The method to use for distributing GCP candidates.

Available options are:

Entire: Target number of GCP candidates for each reference image, distributed evenly throughout the reference image. Larger numbers produce a more dense set of candidates, which may increase GCP-collection time.
Map Spacing (meters): Minimum distance, in meters, between GCP candidates. Smaller numbers produce a more dense set of candidates, which may increase GCP-collection time.
Pixel Spacing: Minimum distance in pixels between GCP candidates. Smaller numbers produce a more dense set of candidates, which may increase GCP-collection time.

Distribution Amount

The distance between GCP candidates or the total number of GCPs to generate.

The meaning of the value of this parameter depends on the value of the Distribution Method parameter; that is, the value may be number of GCP candidates or a distance, in meters or pixes.

Candidate Trials

The number of trials per candidate.

A trial is an attempt to match a candidate point between the reference image and the input image. You can specify a value ranging from zero through three. If you specify a value greater than one, and the first attempt fails, another attempt is made to match the points. For example, if you specify a value of 3, up to three attempts is made.

Tip: If there are insufficient stereo GCPs, use a denser distribution rather than more trials, because subsequent attempts occur only if the primary attempt fails for a given image.

A higher value may increase GCP-collection time.

Chip Size

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.

Details

General job details

Module details

The Chip Database Generation module extracts GCP candidates and generates a chip database from input image tiles.

Job results

For each input tile, a chip database is generated and placed in the intermediates folder. The name of the output chip database file is based on the name of the input image file, with ".cdb" appended to the name. After the creation of chip databases from individual tiles, all chip databases in the intermediates folder will then be merged to produce a final output.cdb file in the specified output folder.