AUTOMOS

Description

AUTOMOS composes a set of georeferenced images into an image mosaic, or into a series of mosaic tiles. This may include the automatic selection of cutlines and color balancing.

Parameters

Name	Type	Length	Value range
Input: Input file name *	Raster port	1 - 192	1 - 4096
InLUT: Input LUT name	LUT port	0 - 1024	0 - 4096
Mosaic Type	String	0 - 1	NONE, PREVIEW, FULL
Output: Output file name	Raster port	0 - 1
Starting Image for Mosaicking	String	0 - 1
Perform Radiometric Correction	String	0 - 1	NONE, HOTSPOT, ADAPTIVE Default: NONE
Color Balancing Method	String	0 - 1	NONE, OVERLAP, HISTOGRAM, REFERENCE, LUT Default: NONE
Histogram Option	Integer	0 - 4	0 -
InputRef: File name of color balancing reference image	Raster port	0 -
Local Mask	String	0 - 1	NONE, BIT Default: NONE
InputBitmap: Input global bitmap mask file name	Bitmap port	0 -
Cutline Generation Method	String	0 - 1	MINDIFF, MINRELDIFF, EDGE, ENTIRE Default: MINDIFF
InputVector: Input file name of the file containing cutlines	Vector port	0 -
OutputVector: Output cutline vector file name	Vector port	0 - 1
Output LUT Layer: Output lookup table segment numbers	LUT port	0 - 1	Default: NONE
Blend Width	Integer	0 - 1	0 -
Input Background Value	Float	0 - 1	Default: 0.0

* Required parameter

Parameter descriptions

Input: Input file name

Specifies the list of input image layers to be processed.

InLUT: Input LUT name

Specifies the input Lookup Table (LUT) layer to be used in the output mosaic.

Mosaic Type

Specifies the type of output mosaic to create.

Valid options are:

• NONE: No output mosaic will be created
• PREVIEW: Generates a downsampled mosaic
• FULL: Generates a full-resolution mosaic

This parameter may be empty only if output cutlines or LUTs are specified, but no output mosaic is required.

Output: Output file name

Specifies the path and file name of the single file that will contain all channels of the output mosaic image.

If the mosaic image is to be output as a single file, this parameter specifies the path and file name of the file that will contain all channels of the mosaic image.

If the mosaic image is to be separated into tiles, this parameter will be used as part of the path and file name for each file that will contain all channels of one tile of the output mosaic image. For more information about tiling, see the Function Details section.

This parameter may be empty only if MOSTYPE (Mosaic Type) is empty or set to "NONE".

Starting Image for Mosaicking

Specifies the file name of the image file that AUTOMOS will add to the mosaic first. By default, AUTOMOS finds the most central image, and increases the mosaic size by adding the next closest image.

Because the starting image is also the starting point for color balancing operations and cutline selection, it is generally advisable to use a central image with good radiometry.

Perform Radiometric Correction

Specifies the normalization filter to apply to the orthorectified images before they are compiled into a mosaic.

The following values are supported:

• HOTSPOT: removes hotspots from the images
• ADAPTIVE: balances the brightness and contrast in the images
• NONE: does not apply normalization filter

Color Balancing Method

Specifies the method to use for color balancing across images to be mosaicked.

The following values are supported:

• NONE: no color balancing is performed

• OVERLAP: color balancing is applied based on matching overlapped areas of the input images.

  This option requires sufficient overlap (larger than 10 percent) between each pair of adjacent input images with good quality georeferencing. It is not effective if the same features in overlapping images appear different due to variations in illumination and view direction between images.

  If you use this color balancing method and are specifying a local (LOCLMASK) or global mask (GLOBMASK), your mask must have some pixels within the overlap area in order to affect the output.

• HISTOGRAM: color balancing is applied sequentially, by matching the input image histogram with the target mosaic image.

  The HISTOGRAM option can include histogram trimming, which requires that a trim percentage value be given through the BALOPT (Color Balancing Options) parameter, along with the perferred match area size. This option works in a sequential manner, matching each input image with the destination mosaic image.

  HISTOGRAM also supports the use of exclusive masks.

  Because this option does not require very precise georeferencing and overlap, it may be beneficial when working with larger data sets.

• REFERENCE: color balancing is applied by matching the input image histogram with the specified reference image.

  The reference image file is specified by FILI_REF; this option matches the histogram of each input image with that of a reference image.

  REFERENCE also supports the use of exclusive masks.

  Because this option does not require very precise georeferencing and overlap, it may work better with image sets having consistent radiometric distribution.

• LUT: color balancing is applied based on the input LUT segment numbers.

  Specify the input LUT segment numbers using BALOPT (Color Balancing Options).

Histogram Option

Specifies options for color balancing. This parameter applies when the BALMTHD parameter is set to HISTOGRAM, REFERENCE, or LUT.

If BALMTHD (Color Balancing Method) is set to HISTOGRAM, the histogram area and trim settings can be adjusted by using BALOPT (Color Balancing Options) to indicate the area multiple and the trim percentage. In this case, two input values are required:

• Area multiple: Must be a value greater than 1 representing the percentage of the area in the mosaic file that will be used to calculate the color balancing histogram. The row and column dimensions of the input image are multiplied by this value to define the dimensions of a subregion of the target image for which the target image histogram that is used in the histogram matching operation is computed. The subregion is positioned within the target image such that its center is at the georeferenced center of the input image. The default value is 3.
• Trim percentage: A number representing the percentage removed from the upper and lower parts of the histograms range. Trimming means to ignore the specified trim percentage of the total histogram area from the ends of both tails in a gray-value histogram when matching with another target histogram. Trimming will be applied on both the input image and the target image. The default value is 2 percent.

If BALMTHD is set to REFERENCE, use BALOPT to specify reference image channels.

If BALMTHD is set to LUT, use BALOPT to specify input LUT segment numbers.

InputRef: File name of color balancing reference image

Specifies the file name of the reference image file to use when BALMTHD (Color Balancing Method) is set to REFERENCE.

It is not necessary for the reference image to have the same resolution or projection as the input images. When the reference image has different projection from that of the input images, the reference image can be used as long as neither is in the PIXEL, METER, or FOOT projection.

By default, the reference image channels appear in the same order as the channels specified in DBICLIST; that is, the i'th channel in the reference image will be matched with the i'th channel in the DBICLIST in input images. You may, however, use BALOPT (Color Balancing Options) to re-map these channels.

When re-mapping channels , a list of re-mapped channels are specified through the BALOPT parameter. The i'th number in this list is the channel that will be matched to the channel whose number is the i'th number in DBICLIST.

Local Mask

Specifies whether a bitmap in an input file will be used as an exclusion mask for mosaicking.

If LOCLMASK is set to BIT, the individual bitmap in each input image file will be used as an exclusion mask. If the file contains multiple bitmaps, the last one will be used.

An exclusive individual bitmap layer is contained in each input image file with a valid georeference. The values in a bitmap are either 1 or 0, represented by each bit, and are referenced to each pixel in this image. When processing an image with the individual bitmap consideration, an image pixel with a relevant bit value of 1 will be excluded; if the bit value is 0, that pixel will be used.

The bitmap exclusion is used in cases where some surfaces (for example, the surface of water bodies) can appear radically different in the orthorectified and reference images due to ephemeral phenomena such as specular reflection of sunlight. Another example that may be relevant in a very large scale application is a parking lot that is full of cars in one image and empty in another.

InputBitmap: Input global bitmap mask file name

Specifies the path and file name of the global exclusion mask bitmap file.

If this parameter is set to a file name, the bitmap in that file will be used as an exclusion mask for mosaicking. If the file contains multiple bitmap layers, use the GLOBMASK (Global Mask) parameter to specify the layer number of the bitmap to be used.

Cutline Generation Method

Specifies the method used to collect cutlines for mosaicking.

The folllowing values are supported:

• MINDIFF: specifies the "minimum difference" option

  This method applies to most mosaicking projects. The algorithm determines a cutline in each overlapped area between two adjacent images that contain the minimum differences of gray values at the same locations of the region.

• MINRELDIFF: specifies the "minimum relative difference" option

  The algorithm determines a cutline in each overlapped area between two adjacent images with minimum differences of gray-value gradients at the same locations of the region. This approach is most effective in cases where the display of the same sections of a scene appear very different in different images.

• EDGE: specifies the "edge feature" option

  This algorithm uses a combination of Minimum Difference and Minimum Relative Difference to determine the optimum location for the cutlines. This approach is most effective in urban area mosaicking, or in a scene with many linear features. The objective of the EDGE method is to avoid placing cutlines across linear features.

• ENTIRE: specifies that the entire images will be added to the mosaic. This option is used to mosaic images that do not overlap. The algorithm uses the four corner coordinates of the images as the cutlines, according to the stacking order.

InputVector: Input file name of the file containing cutlines

Specifies the input file or layer containing vector cutlines.

Vector data describing cutlines are read from the specified file and used in the mosaic composition. If input image files do not contain cutlines, new cutlines are generated according to the value of the CUTMTHD (Cutline Generation Method) parameter.

The number of the vector segment in the specified file from which the cutlines are to be read is specified with in DBIV (Input Vector Segment).

OutputVector: Output cutline vector file name

Specifies the path and file name of the file in which new cutlines will be saved.

If the cutlines are to be stored in an existing vector segment, the number of that segment must be specified with the DBOV (Output Vector Segment) parameter.

Output LUT Layer: Output lookup table segment numbers

Specifies the segment numbers in an output lookup table (LUT) in which to store image color balancing information.

If color balancing is requested (see BALMTHD), this parameter allows the user to store the LUT for every image channel.

To create new LUT segment numbers to store the LUTs, set DBLUTO="CREATE" or "0".

To overwrite existing LUT segment numbers, set DBLUTO equal to the segment numbers.

If one or more segments numbers are specified, the format of the output files must PCIDSK.

Blend Width

Specifies the perpendicular distance, in pixels, from the cutlines over which image blending will be performed.

Image blending means to average each pixel gray value in the blending strip along a cutline from both overlapped input images with a weight. The weight is the perpendicular distance between the pixel and the strip edge divided by 2 times of the blend width; the new blended pixel value is the weighted average of the two overlapped images.

If BLEND is empty, an optimum value (up to a maximum of 5 pixels) is estimated and used.

Input Background Value

Specifies the background value of the input image channel.

OrthoEngine uses a background value of zero for orthorectified or geometrically corrected images, so the Mosaic Area also has a background value of zero by default. However, images orthorectified or geometrically corrected outside of OrthoEngine may have a background value other than zero.

Pixels having the specified background value within an input orthorectified image are interpreted as non-image values; this ensures that the output mosaic contains only valid data from the input images.

Details

AUTOMOS composes a set of georeferenced images into an image mosaic. This may include color balancing and the selection of cutlines. Note that any changes in color balancing methods used will affect cutline generation and the final mosaic result.

Specifying input text file parameters

If the value of MFILE (Input File) is a text file, the files and parameters values listed in the text file will be used as input. The parameters in the text file must be delimited by semi-colons and appear in the following order:

[FILE] ; [DBICLIST] where DBICLIST is optional

For example:

"C:\pci\irvine.pix"; "1,2,3"

In the example above, the input channel list (1,2,3) is specified in the text file. If the input channel list is not given, it will be taken from the DBICLIST parameter.

Specifying output text file parameters

If the parameter FILO (Output File) is set to an existing text file, it can be used to create more than one mosaic at a time. You can specify already existing mosaic files, or you may create new tiles by specifying the upper-left (ULX, ULY) and lower-right (LRX, LRY) boundaries for each output mosaic tile.

To create output mosaic tiles:

1. Set the FILO parameter to a text file.

   FILO=tilespecs.txt

2. Create a text file that contains one line for each tile output file that you want AUTOMOS to create or update.

   Each line of the text file uses the same convention of specifying a file name and, optionally, specifying bounds. The parameters in the output text file must be delimited by semi-colons and appear in the following order:

   [FILE];[ULX];[ULY];[LRX];[LRY]

Example

The following example text file content specifies two output mosaics that are at the same x-position and are adjacent to one another in the y-dimension.

"C:\pci\Mosaic1.pix"; 350000; 4800000; 370000; 4750000
"C:\pci\Mosaic2.pix"; 350000; 4750000; 370000; 4700000