Distortion-free Image Creation module

Description

The Distortion-free Image Creation module resamples raw imagery to compensate for distortions in aerial photos. The distortion can be from various sources such as the camera lens, atmospheric refraction, earth curvature and other unpredictable errors. The module reads a valid CATALYST Professional OrthoEngine project file (.prj) which contains a BINGO grid correction file. The distortion-free images can be directly used in stereo measurement, image epipolar generation and can also benefit image matching.

Parameters

Name	Caption
Input File	OrthoEngine project file containing the grid correction file
Output Folder	Folder for output files
Overwrite Results	Overwrite existing results
Send Email	Email notification settings
Output Background Value	Output background value
Image Set	Images to process
Image Set Options	Additional options for the image set
Lens	Whether to correct lens distortions
Distortion Types	Distortion types to correct
Points to be corrected	Whether to correct point distortions
Points Types	Point types to correct
Resampling Method	Resampling method
Resampling Method Extra Options	Extra options for resampling method

Parameter descriptions

Input File

The path and name to an OrthoEngine project file that contains raw images and it references a BINGO grid correction file

Output Folder

The path and name of the folder to which to write distortion-free images and an updated OrthoEngine project file.

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.

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.

Output Background Value

The background (NoData) value to use for pixels that are not populated.

The specified background value is truncated to the range allowed by the source image data type.

When you specify one value, all channels are set to the same NoData value. If you want to specify different values for various channels, separate the values with commas. For example, to specify -32768 for channel 1 and zero for channel 2 (and any subsequent channels), enter "-32768, 0".

Image Set

Specifies which images will be processed:

ALL: All images are processed
IMAGES: Specify one or more comma-delimited photo IDs. For example, img001, img002
SUBSET n OF N: Images are divided into N subsets and the n-th subset is processed
MFILE: Specify a text file with an .mfile file name extension that contains IDs of photos to process. For more information on this type of file, see About the MFILE format

Image Set Options

Extra options for the Image Set parameter. Available options are:

IMAGES:img001, img002. Where img001 and img002 are photo IDs
SUBSET n OF N:n OF N. Where N is the total number of subsets and n is the n-th subset
MFILE:The path and name of the MFILE contains IDs of photos to process

Lens

Select this check box to compensate for lens distortions.

Distortion Types

Choose the distortion types to eliminate. Available options are:

ALL: All distortion types including Grid, Radial and Decentering
Grid: BINGO exported distortion grid
Radial: Radial distortion
Decentering: Decentering distortion
Grid and Radial: Grid and Radial distortions
Grid and Decentering: Grid and Decentering distortions
Radial and Decentering: Radial and Decentering distortions

Points to be corrected

Select this check box to specify which points to remove distortions from.

Points Types

This option specifies which points will be included for distortion removal.

Available options are:

BOTH: Remove image distortions of both GCPs and TPs
GCP: Remove image distortions of GCPs, and delete TPs
TP: Remove image distortions of TPs, and delete GCPs

Resampling Method

The resampling method to use during processing.

Available resampling options are:

Cubic: cubic convolution. This method determines the gray level from the weighted average of the 16 pixels closest to the specified input coordinates and assigns that value to the output coordinates. The resulting image is slightly sharper than one produced by bilinear interpolation, and it does not have the disjointed appearance produced by nearest-neighbor interpolation. This is the default value.
Nearest Neighbor: nearest-neighbor interpolation. This method identifies the gray level of the pixel closest to the specified input coordinates and assigns that value to the output coordinates. Although this method is the most efficient in computation time, it introduces small offsets in the output image. The output image may be offset spatially by up to half a pixel, which may cause the image to have a jagged appearance.
Bilinear: bilinear interpolation. This method 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. An image with a smoother appearance than nearest-neighbor interpolation is created, but the gray-level values are altered in the process, resulting in blurring or degraded image resolution.
Lagrange-4: four-point Lagrange interpolation
Lagrange-8: eight-point Lagrange interpolation
Sinc-8: eight-point sin(x)/x
Sinc-16: 16-point sin(x)/x
Average: Average resampler for creating downsampled products
Gaussian: Gaussian resampler
Median: Median resampler for creating downsampled products

Resampling Method Extra Options

When you specify a value for the Resampling Method parameter, you can use the Resampling Method Extra Options parameter to specify additional options. The available options are specific to the following resampling methods:

Sin(x)/x with an 8 x 8 window
Sin(x)/x with a 16 x 16 window
SHAPINGWINDOW=[sw],BETA=[beta]

where:

SHAPINGWINDOW specifies a window to attenuate the SINC coefficients to reduce resampling artifacts. The value can be KAISER, HAMMING, HANN, LANCZOS, PARABOLA, or NONE. SHAPINGWINDOW is optional; the default value is KAISER. BETA is applicable only when SHAPINGWINDOW is KAISER. SHAPINGWINDOW determines the shape of the KAISER window; a larger BETA value produces greater attenuation of the SINC coefficients. Its value can be between 1.0 and 10.0. BETA is optional.

Average
NUMCOLS=[nc],NUMROWS=[nr]
Median
NUMCOLS=[nc],NUMROWS=[nr]

where:

NUMCOLS and NUMROWS can be any value between 1 and 11.
Gaussian
DSFACTORCOL=[dc],DSFACTORROW=[dr]

where:

DSFACTORCOL is the fraction downsampling factor in col (>=1). If not specified, a default factor is computed automatically based on the output and input pixel sizes. DSFACTORROW is the fraction downsampling factor in row (>=1). If not specified, default to the value of DSFACTORCOL.

Note: With each resampling method, the parameters MIN=[min], MAX=[max], and FILL=[NN or BGD] can be appended as a comma-delimited list. MIN and MAX define the clamp range for output pixels. This is useful when you want to keep pixel values within a certain range; for example, 1 to 2047 if 11-bit data is stored in a 16-bit file. FILL defines the behavior when the resampling window contains NoData pixels: NN instructs the resampler to use the Nearest Neighbor method, while BGD indicates that the output pixel is set to the background value. By default, NN is used for FILL.

Details

General job details

Preprocessing requirements

Before running this module, the following requirements must be met to ensure the job processes successfully and produces accurate results:

You must have a valid OrthoEngine project file that points to a BINGO grid correction file.

Module details

The Distortion-free Image Creation moduleresamples raw imagery to compensate for lens distortions. The lens distortions can be represented in radial, decentering and grid forms. The distortion grid can be a discrete form from a mix of all types of contiguous distortion models such as various added self-calibration parameters. With BINGO, the grid can even represent non-lens distortions including corrections from atmospheric refraction and/or earth curvature. This module has two major steps in processing. First, the transformation relationship is established for the distortion-free images. This is done by computing the actual coordinates on the raw image given any ideal coordinates on the distortion-free image using the camera’s intrinsic parameters. Second the values of pixels on the distortion-free photo are obtained by a specified resampling method from the raw photos employing the afore-mentioned transformation.

Job results

The module creates a new OrthoEngine project file that references newly created distortion-free images. The images themselves have the same name and format as the original images that were in the OrthoEngine input project file. With these files you can continue to perform other photogrammetric processes. The distortion free images can be directly used in stereo measurement.