nocam2map

This program will map project a raw instrument cube without a camera model. However, the lack of a camera model requires latitude/longitude information at each pixel in the raw cube. This must be facilitated through a latitude cube and longitude cube with the same size as the raw instrument cube.

The procedure to project the input cube is output driven. That is, we create an output map cube (as specified by the user) and at each output pixel, compute its projected latitude/longitude using the projection parameters. Using this coordinate we must search for that position in the two input cubes (latitude/longitude). If found, we will have a sub-pixel location that has a 1-1 correspondence with the raw instrument pixel. An interpolator (nearest neighbor, bilinear, or cubic convolution) is then used to compute a value for the output pixel.

Therefore, the root of the problem is finding the latitude/longitude in the two input cubes as it is a 2-dimensional search. We do this by first creating two polynomial functions of a user-specified order (DEGREE), one for sample and one for line. These functions, f(lat,lon) = sample and g(lat,lon) = line, are derived using a least-squares computation by collecting a sparse set of control points (line,samp)-to-(lat,lon). The sparseness is controlled by the SINC and LINC. Unfortunately, the polynomial is not accurate enough to supply the mapping to sub-pixel accuracy. The level of errors between the control points and the derived equations can be written to the RESIDUAL file for examination.

To achieve sub-pixel accuracy, we use the polynomials to get us close (generally within 6 pixels). Using this estimated location, two affine transforms are computed by collecting a small 3x3 window of control points. These equations are used to further refine the estimated location. We iterate this process until our estimated sample/line is within an acceptable tolerance (TOLERANCE) of latitude/longitude values contained in the two cubes (LATCUBE/LONCUBE) or until the number of iterations is exceeded (ITERATIONS).

Defining the output map projection is controlled as follows:

• ProjectionName - Should be specified by the map file
• TargetName - Will be searched for in the FROM cube or can be specified by the user.
• EquatorialRadius and PolarRadius- Will be automatically computed from NAIF kernels or can be specified by the user.
• LatitudeType - Will be read from the map file if available, otherwise will be set to the latitude type of the LATCUBE
• LongitudeDirection - Will be read from the map file if available, otherwise will be set to the longitude direction of the LONCUBE
• LongitudeDomain - The longitude domain will be 0-360 by default.
• MinimumLatitude - Can be computed from the LATCUBE, read from the map file or user specified.
• MaximumLatitude - Can be computed from the LATCUBE, read from the map file or user specified.
• MinimumLongitude - Can be computed from the LONCUBE, read from the map file or user specified.
• MaximumLongitude - Can be computed from the LONCUBE, read from the map file or user specified.
• Scale or PixelResolution - Can be computed¹ from the input, read from the map file, or user specified in either meters/pixel (PixelResolution) or pixels/degree (Scale)

        1To compute the scale we find the number of pixels from pixel (1, 1)
        to pixel (nsamples, nlines) in the input cube:
        sqrt[(nsamples-1)2 + (nlines-1)2]
        And the angle across this line:
        acos(cos(latitude_point1) * cos(latitude_point2) * cos(longitude_point1 - longitude_point2) + sin(latitude_point1) * sin(latitude_point2))
        The scale is equal to the number of pixels divided by the angle in pixels per degree.
      

If the program is run on an image with a camera model contained in the label, much of the model information is deleted in the output cube. This avoids display conflicts between the built in display solution of the camera model and that generated by the projection function.

This application fails to produce correct output with smaller cubes sized 5x1, 1x5 or smaller. The error message provided is: "**ERROR** Unable to solve-least squares using QR Decomposition. The upper triangular R matrix is not full rank in LeastSquares.cpp at 402." This issue occurs because there is not enough information provided by small cubes for the equations used.

Description

This will specify the raw instrument cube to be mapped.

Description

The DN values from this cube will be used as the latitude values for the input cube. The number of samples and lines must match the FROM cube.

Description

Specify the latitude type, as either planetographic latitude or planetocentric latitude.

Description

The DN values from this cube will be used as the longitude values for the input cube. The number of samples and lines must match the FROM cube.

Description

Specify the longitude direction, either positive east or positive west.

Description

This file will contain the map projected cube.

Description

The order of the polynomial functions to compute sample/line from latitude/longitude.

Description

The number of samples skipped over when adding points to the polynomial functions.

Description

The number of lines skipped over when adding points to the polynomial functions.

Description

If a file is specified, residuals for each point (line, sample) are written to the file for examination.

Description

If set to true, the output cube will not be processed and warped. The program will simply calculate the polynomial fit with errors.

Description

A file containing the desired output mapping parameters in PVL form. This file can be a simple hand produced label file. It can also be an existing cube label which contains a Mapping group. You can produce map file using the maptemplate program.

Description

This parameter is used to specify how the pixel resolution is obtained for the output map projected cube.

Description

Specifies the pixel resolution in either meters per pixel or pixels per degree.

Description

This will specify the target planet to map from/to, i.e. Mars, Venus, etc.

Description

The equatorial radius can be read using the NAIF routines to get the radius from the specified target planet, or read from the user.

Description

The polar radius can be read using the NAIF routines to get the radius from the specified target planet, or read from the user.

Description

This parameter is used to specify how the default latitude/longitude ground range for the output map projected cube is obtained. The ground range can be obtained from the camera or map file. Note the user can override the default using the MINLAT, MAXLAT, MINLON, MAXLON parameters. The purpose of the ground range is to define the coverage of the map projected cube. Essentially, the ground range and pixel resolution are used to compute the size (samples and line) of the output cube.

Description

The minimum latitude of the ground range. If this is entered by the user, it will override the default camera or map file value. By default, planetocentric latitudes are assumed unless the map file specifies otherwise.

Description

The maximum latitude of the ground range. If this is entered by the user, it will override the default camera or map file value. By default, planetocentric latitudes are assumed unless the map file specifies otherwise.

Description

The minimum longitude of the ground range. If this is entered by the user, it will override the default camera or map value. By default, positive east longitudes in the range of 0 to 360 are assumed unless the map file specifies otherwise.

Description

The maximum longitude of the ground range. If this is entered by the user, it will override the default camera or map value. By default, positive east longitudes in the range of 0 to 360 are assumed unless the map file specifies otherwise.

Description

When computing the sample/line to be mapped from input to output, the sample and line are determined from the polynomial fit function. The transform then calculates the pixel differences in stereographically projected latitude/longitude from the input at sample/line to the output's stereographically projected latitude/longitude. If this difference is greater than the tolerance, then an affine transformation is iteratively used until the difference is less than the tolerance or is set to null after a set number of iterations.

Description

If the tolerance has not been met in the number of iterations specified, then the pixel is not mapped to the output.

Description

This is the type of interpolation to be performed on the input.