This button allows the user to select an image (of up to three
bands) to be loaded. A File Selector panel is
displayed containing a list of images (*.img files) in the
current directory. There are several options at this point:
- The user may select one of the images listed by
clicking the left mouse button on the choice, and
then clicking the OK button,
or by simply double clicking the left
mouse button on the choice.
- The user may select an image from another directory
by typing the directory specification into the box below
the label "File Filter:" and pressing Enter
(or clicking on the Filter button),
or by simply double clicking on the choice
in the box below the label
"Directories". This displays a list of files from the
directory specified.
- The user may also select an image (by clicking the left
mouse button on the choice) and then enter a window and/or
band specification. The image name selected appears in
the text box below the label "Selection:". The window
and/or band specification may then be entered by clicking
the left mouse button in the text box and entering the
specification using standard LAS syntax
(i.e., image_name(sl,ss,nl,ns:b1,b2,b3)). Finally, the
user may type a LAS image name directly in the text box
below the label "Selection:".
Each band of the selected image is loaded into a separate
memory plane and is subsampled, if necessary, to fit into the
defined size of the memory plane. A scale and offset are also
calculated and applied to the image data if the input data
is not byte data.
All of the bands of an image required during a TIEPTS session
should be loaded at the same time. Switching from one band to another
during the session is accomplished by changing planes in the Show
panel, which is much more efficient since any subsampling or rescaling
does not have to be repeated. The Load button is not disabled
after the user has begun selecting points, which is intended to allow
loading another band of the same image. Loading a second image after
tie point files have been opened and selecting has begun will cause problems.
TIEPTS has been designed to work with both 24-bit and 8-bit
color displays. In order to display a 3-band color image
on an 8-bit color display (pseudocolor visual), the 24 bits
of image data must be compressed to 8 bits. The color
compression algorithm used is a median cut color compression
algorithm taken from code developed for NASA JPL by the
California Institute of Technology in 1989. This algorithm
produces an image with the specified number of colors along
with a colormap used to display the image. TIEPTS actually
reduces the image to 200 colors (rather than 256) in order to
reserve 56 colors for other operations. Single-band black and
white images are also reduced to 200 gray level values.
Display of images on 24-bit displays (directcolor visual)
requires less compression of the image data but still
requires some compression in order to reserve a number of
colors for other operations. Each band of a color image is
essentially reduced to 7 bits resulting in a 21-bit (rather
than a 24-bit) image. As described for pseudo-color displays,
a single-band black and white image is reduced to 200 gray
level values for output to a 24-bit display.
- OK
- This button accepts the currently selected image
and proceeds with loading the image.
- Filter
- This button applies the currently selected
filter, resulting in a new list of files to select from.
- Cancel
- This button closes the panel without loading an image.
This mapping function allows the user to interactively adjust the brightness
and contrast of the displayed image using slide bars. The Red,
Green, Blue, and All radio buttons allow the user to
select which of the mapping components to adjust. Each displayed image has
three separate mapping components: one for the red, one for the green, and
one for the blue portion of the mapping.
- Red
- This radio button selects only the red component of the mapping to be
adjusted. The green and blue components will not be changed.
- Green
- This radio button selects only the green component of the mapping to be
adjusted. The red and blue components will not be changed.
- Blue
- This radio button selects only the blue component of the mapping to be
adjusted. The red and green components will not be changed.
- All
- This radio button (the default) selects all components
of the mapping to be adjusted equally.
- Brightness
- This slider adjusts the slope of the linear map.
- Contrast
- This slider adds a constant intensity value to
the entire image.
- Linear
- This button removes the current adjusted mapping,
and replaces it with the original, or identity, mapping.
- Dismiss
- This button saves the current adjusted mapping and closes the panel.
This function displays line/sample values in both image
and file coordinates and displays a matrix of gray level values
surrounding the point of interest. Optionally, the user may
choose to display:
- Projection coordinates
- Latitude/Longitude coordinates
- Unscaled gray level values
This information may be presented for any displayed image
window (e.g., main image window, full resolution image window,
or zoom image window) by using the mouse to move the cursor
into the appropriate window. Single-stepping the cursor is
also provided for precise movement through a keyboard interface.
The "h", "j", "k", and "l" keys are special
and are used to move the cursor left, down, up, and right one pixel
respectively, in addition to the four arrow keys. Using the shift key in
combination with a special or arrow key moves the cursor ten pixels
in the corresponding direction.
- Gray Level Matrix:
- This matrix box shows a 3X3 matrix of gray level values
(or pixel intensity values) for the red, green, and blue components
of the image. For grayscale images, the information is repeated
three times. The center value is the gray level value of the
current cursor position and the remaining matrix values are the
values immediately surrounding the center pixel.
- Line/Sample:
- This text field displays a one-relative coordinate
which is calculated from the upper left corner of the displayed
image. Therefore, the upper left coordinate will always be
1,1, and the lower right coordinate will be the size of the
displayed image.
- File Coordinate:
- This text field displays a one-relative line and
sample coordinate which is calculated from the upper left corner
of the original disk image. This coordinate may differ from the
line/sample coordinate described above by the window loaded,
the subsampling, and/or the zoom factor applied.
- Projection Coord:
- This text field displays a coordinate which
represents the X/Y position of the cursor in the coordinate
space defined by the map projection of the image. The corner
coordinates, as well as the units these coordinates are specified
in (e.g., meters), must be stored with the image for this
option to function. An error message will be displayed
if the appropriate information is not available.
For LAS images, this information is stored in the image DDR.
- Lat/Long:
- This text field displays a coordinate which represents
the latitude/longitude position of the cursor. TIEPTS uses the
geometric transformation package GCTP to calculate this position.
Therefore, the corner coordinates (in projection coordinates) of
the image, as well as 15 projection parameters defining the projection,
must be stored with the image for this option to
function. An error message will be displayed if the
appropriate information is not available. For LAS
images, this information is stored in the image DDR.
- Unscaled:
- This text field displays values which represent an approximation
of the original red, green, and blue gray level values
of the current point. This option applies only if the original
image data was two-byte integer, four-byte integer, or floating
point data which requires the image data to be scaled at load
time. These values are only approximations since the original
values are not read from disk but are calculated based on the
scale and offset applied to the data when the image was loaded.
- Dismiss
- This button closes the panel.
TIEPTS is designed as an interactive production tool. To avoid complexity,
very few panels are present at any given time. While capabilities such as
viewing image segments at full resolution and zooming are intuitive, some
user-definable parameters are required to better utilize these capabilities.
In addition, there are system parameters, such as the pathnames of the input
and output tie point files, that need to be defined. To provide
user-definable parameters, yet minimize the number of panels, the
Parameters panel was designed.
The panel varies slightly from one TIEPTS mode to another, since each
mode requires specific options (for example, the Digitizer Port is
only required for Image to Map mode). However, certain parameters
are common to several or all modes.
- Accept
- Apply
- Values entered in the panel are not applied until
the Accept or Apply button
is pressed. The Accept button applies
the updated parameters and removes the panel. The
Apply button applies the updated parameters
but keeps the panel
active. This is convenient for analyzing the effect of modifying a
given parameter.
- Cancel
- This button resets any updated parameters to their previous
values and closes the panel. Updated parameters are
those which have been modified since the last Apply
or Accept.
2.4.1 Common Parameters
- Ref Input TPS
- Search Input TPS
- The reference input tie point file is a file from which
previously selected reference points are to be loaded.
The Ref Input TPS button
provides a File Selector from which the existing TPS file may
be selected. The selected TPS file pathname will be displayed
in the text field region below the button. Optionally, the
name of the TPS file may be typed directly into the text field.
The search input tie point file is a file from which
previously selected search points are to be loaded. This
file should correspond with the reference input tie point
file. The functionality of the Search Input TPS
button and text fields are the same as the Ref
Input TPS.
If the source of the tie points in a TPS file is an image, the name
of that image is included in the TPS file. In IM2IM mode, the
source of both the reference and search input TPS files is an
image. If both input TPS files are specified, the corresponding
image(s) will automatically be loaded when the Select
button is pressed. Once tie point selecting has begun, any changes
to these parameters is ignored.
- Ref Output TPS
- Search Output TPS
- The reference output tie point file is the destination for
all points selected from the reference frame. Similarly,
the search output tie point file contains the line and sample
locations of the selected points from the search image.
If output tie point file names are not entered here, default
filenames are generated based on the image name, and the user
is requested to confirm or change these names when the
image(s) are loaded. Once tie point selecting has begun, any changes
to these parameters is ignored.
- Zoom Method:
- When an image is zoomed, the output space is defined first, then the
pixel values in that space are determined by finding their
corresponding location in the input image. The pixel location
in the input image is a floating point value; i.e., it can fall
between pixels. A method of interpolating a brightness value
for that pixel location is therefore needed. The options listed
below range from the fastest but least accurate to the slowest but most
accurate method. The default is Cubic Convolution,
which is the most computationally intensive but produces the smoothest
output. This options works well for most applications. As
Zoom Factor and Zoom Size increase,
however, the default may be too time consuming to be useful,
- Nearest Neighbor
- Uses the brightness value of the pixel closest to the calculated
floating point pixel. This the fastest method of the three, but will
result in 'blockier' looking images.
- Bilinear
- Uses a 2x2 block of input pixels which surround the
calculated floating point pixel value to determine the output
pixel brightness value. This method is the middle of the three, in both
speed and accuracy.
- Cubic Convolution
- Uses a 4x4 block of input pixels which
surround the calculated floating point pixel value to determine the output
pixel brightness value. This is the slowest method but gives the
smoothest looking output images.
- Alpha:
- Parametric cubic convolution alpha parameter. This value is used with
Cubic Convolution in generating the zoomed image window.
Commonly used values are -1.0 and -0.5; values -3.0 through 3.0
produce reasonable results.
- Zoom Factor:
- Defines the factor to be used when zooming image data. This
value may be modified by typing directly into the text
field or by using the arrow buttons adjacent to the
text field. The zoom factor is limited to 2 through 16.
Larger zoom factors will require more time to calculate and
more memory to store the zoomed image data.
- Zoom Size:
- Defines the size of the region in the image to be zoomed. The valid options
are 64x64 and 128x128 pixels. The size of the zoom window containing this
region will be the
zoom size times the zoom factor. By default, the zoom size is set
to 64x64 and the zoom factor is 4, resulting in a 4*(64x64) = 256x256
zoom window.
- Full Size:
- Defines the size of the full resolution window that appears when
a point is selected. The selected point is the center of this window.
The default size is 256x256 except in IM2MAP mode, where it is 512x512.
- Cursor
- This button defines the color of the cursor in all windows. The
color of the cursor changes immediately; it is not dependent on the
Accept or Apply buttons.
- Order:
- Defines the degree of the polynomial
(see Transformation,
and Rough Transformation).
This order affects the accuracy of the transformation (it
has no effect on the value of the selected points). A transformation
using a first degree polynomial cannot be performed until at least
4 points have been selected or defined from the image DDR. If a
second degree polynomial transformation is selected, a first degree
is actually used until 7 points are defined.
- Ref Size
- Defines the horizontal and vertical size of the image chip that surrounds
each selected point. These values are written to the output TPS files
and used by other LAS applications.
- Search Offsets
- Defines the horizontal and vertical search offsets for each
selected point. These values are written to the output TPS files
and used by other LAS applications.
- Elevations:
- Defines whether or not the user will be required to enter an elevation
value for each selected point. If set to Required,
the elevation text item is blank, and the user is required to enter
a value or the point cannot be accepted. If set to
Not Required, the default elevation value is set to 0.0. This
value is written to the output TPS file and used by other LAS applications.
2.4.2 Image to Map Parameters
The following parameters are specific to Image to Map mode.
- Entry Mode:
- Defines the method by which map coordinates will be entered. If
set to Digitizer, points will be sparked on a digitizer and
passed through the Digitizer Port. If set to Manual,
a panel will appear for entry of map coordinates.
- Digitizer Port:
- Defines the serial I/O port that the digitizer is connected to.
2.4.3 Image to Vector Parameters
The following parameters are specific to Image to Vector mode.
- Vector Data Source:
- Defines the type of vector data to be loaded and displayed. Once
selected and displayed, the data type should not be changed during a
TIEPTS session. Doing so will cause the program to fail. This parameter
also affects the appearance of the Vector panel. Vector data currently
supported include:
- DCW - Digital Chart of the World
- DLG - Digital Line Graph
- WDB - World Data Bank II
- CD Pathname:
- Defines the root directory of mounted Compact Disks. CD's are
typically used for DCW and DLG data.
This function allows the user to select which plane numbers
are to be displayed in the red, green and blue channels or to
select which plane number is to be displayed as a black and
white image. The Red, Green, Blue, and B/W
radio buttons allow the user to select which channel the selected plane
is to be displayed in.
- Red
- This radio button indicates the user is currently choosing the plane number
to be displayed in the red channel. Once the corresponding plane number
has been selected, the label changes from Red to the plane number selected.
- Green
- This radio button indicates the user is currently choosing the plane number
to be displayed in the green channel. Once the corresponding plane number
has been selected, the label changes from Green to the plane number selected.
- Blue
- This radio button indicates the user is currently choosing the plane number
to be displayed in the blue channel. Once the corresponding plane number
has been selected, the label changes from Blue to the plane number selected.
- B/W
- This radio button indicates the user is currently choosing the plane number
to be displayed as a black and white image. Once the corresponding plane
number has been selected, the label changes from B/W to the plane number
selected.
- Plane List
- This button shows the user a list of plane numbers that contain valid image
data. The user chooses the plane numbers to be displayed in the selected
channels from this list (see description of radio buttons above).
- Apply
- This button displays the selected planes in the appropriate channels. On
8-bit displays, displaying a color image with the show function implies the
selected planes must be sent through the color compression algorithm.
- Dismiss
- This button closes the panel.
This function allows the user to begin selecting points in
the displayed image(s). It checks to make sure that image(s) have
been loaded, makes sure that output tie point selection files have
been specified, and opens the tie point files. If input tie point
selection files have been selected, their contents are copied to
the output files at this time.
All existing tie points are displayed in the graphics plane,
the Rough Transformation
is calculated, and the cursor is placed into the appropriate window.
Because files have been created and opened at this point,
the Load and Select buttons
are disabled. No changes or additions to image and/or tie point
file names may be made after Select has been clicked.
If changes are required, the user must Exit the TIEPTS
program and run it again.
This function displays and allows editing of the
selected points. A typical use of the Edit
panel is to review the currently selected points, and experiment
with disabling suspicious (high residual) point(s) to see if
the residuals of the remaining points become better or worse.
Current editing functions are:
- Disable
- This button disables the selected point (the point is selected by clicking
the left mouse button on the line of text describing the point).
The transformation recomputes the residuals of the remaining
points. The disabled point is not
physically removed from the display. If in IM2VECT mode, the
full resolution overlay vectors will be redrawn using the new
transformation.
A disabled point is re-enabled by selecting the point and clicking
on the Disable button again.
- Reselect
- This button updates the full resolution and zoom windows for the
selected point, allowing reselection of the point.
- Delete
- This button removes the selected point from the output tie point
selection files.
- Dismiss
- This button closes the panel.
This function allows modification of the tie point graphical
representations. Tie points are displayed on the reference and
search image windows. The color used to display these points may be
modified using the Color button. The display
of the points may be toggled Off/On for both the reference and
search image windows.
This function displays a graphical plot of residuals, which may be useful
in analyzing their distribution. Residuals are represented by lines
starting at coordinate (0,0) and extending to the residual (line, sample)
value. All endpoints are then connected. Ideally, the diagram
should appear "flower-like" meaning the residuals are evenly
distributed.
Figure 1.8.1: Rose Diagram