Region Markers
Summary:
- Geometric region markers can be placed on the screen interactively
or via the XPA "regions" public access point. (Note that "regions" and
"markers" are used interchangeably throughout the SAOtng documentation.)
- To define a data region (by default, an "Include in Source" region):
- Click on the Cursor Pull-down Menu to select a region
shape. Circle, Rectangle, and Ellipse,
Polygon, Point, Line, and Text are supported.
- Move to the desired image location and click the left
mouse button. Optionally, you can drag the mouse with the
left button pressed to specify the initial size of the region.
- Move to the interior of the region, click and drag the left
mouse button to move to another image location.
- Move to the perimeter of the region, click and drag the left
mouse button to change the region size.
- Use the Shift key and left button together to rotate
ellipses, rectangles, and polygons.
- Use the Ctrl-l and Ctrl-r to lower and raise regions
which are contained within or contain other regions. The active
region gets a thickened border and can be moved, resized, etc.
- To change region type, move cursor to the interior of the region and:
- Type "Ctrl-b" to change from source to background region.
- Type "Ctrl-s" to change from background to source region.
- Type "Ctrl-e" to change from "include data with region" to "exclude
data within region".
- Type "Ctrl-i" to change from "exclude data with region" to "include
data within region".
- To delete region, move to the interior of the region and use Delete key.
Contents of This Section
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Regions provide a means for marking particular areas of an image
for further analysis. A common example is to mark a circular region
within which counts from an x-ray source are accumulated, and an
adjacent annular region within which background counts are
accumulated. Net source counts can then be determined by subtracting
the background counts, normalized to the source region area, from
source counts. Regions may have "include/exclude" attributes, meaning
include (or exclude) data in this region in the analysis. For example, an
annular region may be described as an "include" circle and an "exclude"
circle at the same location but with a smaller radius.
The following region descriptors are defined:
- +/-circle(x center, y center, radius)
- +/-box(x center, y center, width, height, rotation angle)
- +/-ellipse(x center, y center, a width, b height, rotation angle)
- +/-line(x start, y start, x end, y end, rotation angle)
- +/-point(x, y)
- +/-polygon(x1, y1, x2, y2, ... xn, yn)
- +/-text(x, y, text)
In all cases, "+" refers to "include" regions and "-" to "exclude"
regions. Coordinates are given in:
- int or float physical pixels of the current image
- int or float degrees, if a "d"is appended to the value
- WCS h:m:s and d:m:s if sexegesmal ":" syntax is employed
- WCS coordinates if a "format" comment is in the region header
N.B. The origin of the pixel coordinate system is
at (1,1), following IRAF and FITS conventions.
Regions may be created by clicking the left mouse button in the
display window, and repositioned by clicking and dragging the left
mouse button in the region interior. They may be moved on a fine scale
by the use of the l(eft), r(ight), u(p), and d(own) keys (one image pixel
per stroke) or the L,
R, U, D keys (5 pixels per stroke).
Closed markers (circles, ellipses, etc.) may be resized by clicking
and dragging the left mouse button on the region perimeter. Note that
for ellipses, dragging vertically or horizontally changes the aspect
ratio of the figure. Rectangles may be resized by clicking and
dragging the left mouse button while on a corner of the figure.
When the mouse is moved inside a marker, the right mouse button will
display a menu containing the following options for that marker:
- Set Name (and Color)
- Set the region name for this marker.
See Changing Region Names
for more information about the region name/color mapping scheme.
- Set Color
- Set the color for this marker. Note that not all colors
have corresponding region names.
- Set Shape
- Change the shape of this marker. Supported markers are:
- Circle
- Ellipse
- Line
- Point
- Polygon
- Rectangle
- Set Include/Exclude
- Set the include/exclude specification for this marker. This also
can be set with the "Ctrl-i" (for include) or "Ctrl-e" (for exclude) keys.
- Attach/Edit Text
- Attach text to this marker. When selected, a dialog box is
displayed into which you can type multi-line text (or edit existing
text). Use ^M to add a new line. Use ^P and ^N to move between
lines of text. The attached text will move with the marker.
- [Hide|Show] Text Display
- Turn on/off the text associated with this marker.
- Marker Analysis Tasks ...
- Display a menu of analysis tasks for this marker and this image.
Selecting on of the menu items will run the associated task.
See Marker Analysis For SAOtng for
more information.
- Display This Marker's Fix Params
- Display the current state of this marker's fix
parameters, which determine whether the marker can be
moved, resized, rotated, deleted, zoomed, etc.
See Fixing/Freeing Regions for
more information.
- Edit This Marker's Fix Params
Modify the state of a marker's fix params. A dialog
box is displayed that contains the current state of
these params. Edit the values in the dialog box, and
press [Return] to commit changes.
See Fixing/Freeing Regions for
more information.
- Fix This Marker Using Global Fix Parameters
- Reset the state of this marker's fix parameters
to match the global state set by the -fix command
switch or by the Edit Global Fix Params For New Markers
option in the Markers menu.
See Fixing/Freeing Regions for
more information.
- Free This Marker
- Unset all previously fixed parameters for this marker.
See Fixing/Freeing Regions for
more information.
- Zoom within Marker
- Zoom the image so that what is inside the marker is displayed in
the entire screen. (Why would you want to do this?)
- Destroy
- Destroy this marker. Also can be accomplished using the Delete key
within a marker.
By default, region have named attributes of "source" or "background"
and "include" or "exclude". The "source/background" region name
mapping can be changed modified easily; see Changing Region Names for more
information. Default attributes may be changed with the
Ctrl-s(ource), Ctrl-b(ackground), Crtl-i(nclude), and Ctrl-e(xclude)
keys, while the cursor is positioned in the region interior. Different
colors correspond to different region attributes: green for "source",
red for "background". Include makers are solid lines, exclude markers
are dashed lines.
Region definitions are not used within SAOtng itself. Rather, they are
communicated to external programs which understand them, either
through the X Public Access Mechanism, or via files. Therefore, they
must be output or converted to a format usable by the external
program. In particular, SAOtng regions follow the syntax
defined in the IRAF/PROS data analysis system.
Regions may be saved to files by selecting Save Regions from
the Markers Pull-down Menu or by using the "regions" public
access point. The region parameters as well as any attached text is
saved in the region file. Position values are saved in the
user-specified format but this can be overridden. See the "regions"
documentation in the XPA Access Points
for more information.
The text marker can be used to place text anywhere on the image. Use
the ^t (control-t) in the image window will bring up a dialog box into
which you can enter marker text. Multi-line text is available by using
^M to add new-lines to the text. Use ^P and ^N to move between lines
of multiple text.
You also can attach text to a marker, so that the text stays with
the marker when it is moved. Once a marker is created, the right mouse
buttons will bring up a menu with "Attach/Edit Text" as an option.
If you choose this option, a dialog window is displayed that allows
you to enter new text (or edit existing text). The resulting text will
be displayed near the marker. You can have multi-line text by using
^M to add new-lines to the text. Use ^P and ^N to move between lines
of multiple text. When saved to a file, the attached text is written
as a comment before the marker (and will be re-loaded as attached text
when the markers in the file are reloaded into SAOtng).
Last Updated July 6, 1998