ISIS 3 Application Documentation
Map project a cube without a camera model
Description
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.
Categories
History
Noah Hilt | 2008-08-01 |
Original Version
|
Christopher Austin | 2009-01-27 |
Fixed parameter names
|
Noah Hilt | 2009-03-02 |
The min/max longitude/latitude are now converted from the input domain to
the map file's domain if necessary.
|
Travis Addair | 2009-08-10 |
Mapping group parameters are now placed into the print file.
|
Annie Howington and Tracie Sucharski | 2012-01-13 |
Updated documentation.
|
Tracie Sucharski | 2012-12-06 |
Changed to use TProjection instead of Projection. References #775
|
Sasha Browsnberger | 2015-02-12 |
If it exists, certain camera model information is removed from the label in the output image.
|
|
Parameter Groups
Files
Name
|
Description
|
FROM |
Input cube to be mapped
|
LATCUBE |
Input cube to read latitude values
|
LATTYPE | The latitude type |
LONCUBE |
Input cube to read longitude values
|
LONDIR | The longitude direction |
TO |
Newly mapped cube
|
Polynomial Fit
Name
|
Description
|
DEGREE | Degree of polynomial functions |
SINC | Sample Increment |
LINC | Line Increment |
RESIDUALS | File to write residuals to |
NOWARP | Specify whether or not to warp the image |
Mapping
Name
|
Description
|
MAP |
File containing mapping parameters
|
PIXRES |
Defines how the pixel resolution in the output map file
is obtained
|
RESOLUTION | Pixel resolution |
TARGET | The target planet to map from/to |
EQURADIUS | Equatorial radius of target |
POLRADIUS | Polar radius of target |
Output Map Ground Range
Affine Correction
Name
|
Description
|
TOLERANCE | Geometric tolerance in pixels |
ITERATIONS | The number of iterations to meet tolerance |
Interpolation
Name
|
Description
|
INTERP | Type of interpolation |
|
Files:
FROM
Description
This will specify the raw instrument cube to be mapped.
Type
| cube |
File Mode
| input |
Filter
|
*.cub
|
Files:
LATCUBE
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.
Type
| cube |
File Mode
| input |
Filter
|
*.cub
|
Files:
LATTYPE
Description
Specify the latitude type, as either planetographic latitude
or planetocentric latitude.
Type
| string |
Default
|
PLANETOCENTRIC
|
Option List:
|
Option |
Brief |
Description |
PLANETOCENTRIC | Planetocentric Latitude |
Sets the latitude to be in planetocentric coordinates.
|
PLANETOGRAPHIC | Planetographic latitude |
Sets the latitude to be in planetographic coordinates.
|
|
Files:
LONCUBE
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.
Type
| cube |
File Mode
| input |
Filter
|
*.cub
|
Files:
LONDIR
Description
Specify the longitude direction, either positive east or positive
west.
Type
| string |
Default
|
POSITIVEEAST
|
Option List:
|
Option |
Brief |
Description |
POSITIVEEAST | Positive East Longitude |
Sets the longitude direction to be positive east.
|
POSITIVEWEST | Positive West Longitude |
Sets the longitude direction to be positive west.
|
|
Files:
TO
Description
This file will contain the map projected cube.
Type
| cube |
File Mode
| output |
Filter
|
*.cub
|
Polynomial Fit:
DEGREE
Description
The order of the polynomial functions to compute sample/line from
latitude/longitude.
Polynomial Fit:
SINC
Description
The number of samples skipped over when adding points to the
polynomial functions.
Type
| integer |
Internal Default
|
Computed
|
Polynomial Fit:
LINC
Description
The number of lines skipped over when adding points to the
polynomial functions.
Type
| integer |
Internal Default
|
Computed
|
Polynomial Fit:
RESIDUALS
Description
If a file is specified, residuals for each point (line, sample)
are written to the file for examination.
Type
| filename |
File Mode
| output |
Internal Default
|
none
|
Polynomial Fit:
NOWARP
Description
If set to true, the output cube will not be processed and warped.
The program will simply calculate the polynomial fit with errors.
Type
| boolean |
Default
| false |
Exclusions
|
- TO
- MAP
- PIXRES
- RESOLUTION
- TARGET
- EQURADIUS
- POLRADIUS
- DEFAULTRANGE
- MINLAT
- MAXLAT
- MINLON
- MAXLON
- TOLERANCE
- ITERATIONS
- INTERP
|
Mapping:
MAP
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.
Type
| filename |
File Mode
| input |
Default Path
| $base/templates/maps |
Default
| $base/templates/maps/sinusoidal.map |
Filter
|
*.map *.cub
|
Mapping:
PIXRES
Description
This parameter is used to specify how the
pixel resolution is obtained for the output map projected
cube.
Type
| string |
Default
| COMPUTE |
Option List:
|
Option |
Brief |
Description |
COMPUTE | Compute pixel resolution from input cube |
This option will automatically determine the pixel resolution
from the input cube. The scale in pixels per degree is computed
by calculating the angle from pixel (1,1) to
pixel (nsamples, nlines) across the input cube and dividing the
number of pixels across the line from pixel (1,1) to
pixel (nsamples, nlines) by the angle.
Exclusions
|
MAP | Read resolution from input map file |
This option will use either the PixelResolution (meters/pixel)
or Scale (pixels/degree) in the map file.
Exclusions
|
MPP | Get pixel resolution from user in meters per pixel |
This option allows the user to specify the pixel resolution in
meters per pixel using the RESOLUTION parameter.
Inclusions
|
PPD | Get pixel resolution from user in pixels per degree |
This option allows the user to specify the pixel resolution in
pixels per degree using the RESOLUTION parameter.
Inclusions
|
|
Mapping:
RESOLUTION
Description
Specifies the pixel resolution in either meters per pixel or pixels
per degree.
Type
| double |
Minimum
| 0.0
(exclusive)
|
Mapping:
TARGET
Description
This will specify the target planet to map from/to, i.e. Mars, Venus,
etc.
Type
| string |
Internal Default
| Read from FROM cube |
Mapping:
EQURADIUS
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.
Type
| double |
Internal Default
| Read from Naif PCK kernel file |
Minimum
| 0.0
(exclusive)
|
Inclusions
|
|
Mapping:
POLRADIUS
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.
Type
| double |
Internal Default
| Read from Naif PCK kernel file |
Minimum
| 0.0
(exclusive)
|
Inclusions
|
|
Output Map Ground Range:
DEFAULTRANGE
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 overide 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.
Type
| string |
Default
| COMPUTE |
Option List:
|
Option |
Brief |
Description |
COMPUTE | Compute default range from input cube |
This option will automatically determine the mininum/maximum
latitude/longitude from the input camera model cube specified
using the FROM parameter.
|
MAP | Read default range from map file |
This option will read the mininum/maximum latitude/longitude
from the input map file. All four values are expected to be
defined.
|
|
Output Map Ground Range:
MINLAT
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.
Type
| double |
Internal Default
| Use default range |
Minimum
| -90.0
(inclusive)
|
Maximum
| 90.0
(inclusive)
|
Output Map Ground Range:
MAXLAT
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.
Type
| double |
Internal Default
| Use default range |
Minimum
| -90.0
(inclusive)
|
Maximum
| 90.0
(inclusive)
|
Greater Than
| MINLAT
|
Output Map Ground Range:
MINLON
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.
Type
| double |
Internal Default
| Use default range |
Output Map Ground Range:
MAXLON
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.
Type
| double |
Internal Default
| Use default range |
Greater Than
| MINLON
|
Affine Correction:
TOLERANCE
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.
Type
| double |
Default
|
1.0
|
Minimum
| 0.0
(exclusive)
|
Affine Correction:
ITERATIONS
Description
If the tolerance has not been met in the number of iterations
specified, then the pixel is not mapped to the output.
Type
| integer |
Default
|
10
|
Minimum
| 1
(inclusive)
|
Interpolation:
INTERP
Description
This is the type of interpolation to be performed on the input.
Type
| string |
Default
|
CUBICCONVOLUTION
|
Option List:
|
Option |
Brief |
Description |
NEARESTNEIGHBOR | Nearest Neighbor |
Each output pixel will be set to the pixel nearest the
calculated input pixel.
|
BILINEAR | Bi-Linear interpolation |
Each output pixel will be set to the value calculated by
a bi-linear interpolation of the calculated input pixel.
|
CUBICCONVOLUTION | Cubic Convolution interpolation |
Each output pixel will be set to the value calculated by
a cubic convolution interpolation of the calculated input pixel.
|
|