Control / Information Windows
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Color Control
All the standard functionality is available for controlling the details
of the display. Data stretching can be based on absolute values or
percentiles of the data itself, and the user can switch easily between the
two. Color stretching can be either to specific values or done
interactively.
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Zoom/Pan
Zoom/pan functionality is provided through a pop-up which presents
a small version of the whole image plus an outline of the portion
currently displayed in the main window. Fractional zoom factors
(e.g. 1.75) are allowed.
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Layer Control
Data overlaid on the images (source maps, coordinate grids, contour
plots, etc.) are handled as a set of map layers and
controlled through the Layer Control window. From here, for instance, the
user can modify symbol sizes, etc. for map overlays. They can
also ask that the tables that were used to make the map be shown.
Sources selected in the table can be highlighted on the image (and
vice versa).
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FITS Header Display
Oasis will display a summary of the information in any FITS file
(including extensions). This tool will be eventually be used to
allow access to extension data and planes in data cubes, though
this capability is not yet available.
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Request Management
All data requests (whether from the Oasis custom archive search functionality,
data references in tables, or from third-party services) are handed off to a
centralized request manager. Since our current services are simple URL data
requests, this is instantiated in a File Transfer Manager front-end through which
the user can monitor all outstanding data requests and control (cancel or redirect)
their progress.
There is an active project at IRSA to implement a more involved Request Management
service (for handling lengthy processing jobs among other things) and another to build
an integrated Data Collection interaction environment. When these and Oasis are
integrated together, the functionality here will be greatly expanded.
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Show Image History
Users frequently wish to quickly switch back and forth
between two or more different images. Oasis provides an
"image history" window which lists the various image files
which have been viewed and remembers the details of the
display in each case.
For example, if the user first displays a DSS image of M31
adjusting the color table, stretch, zoom, etc. then displays a
2MASS image of the same region with a different color table,
stretch, zoom, etc., the image history will remember and reset all
the display details as the user switches back and forth. This
works for any number of images.
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Show Selected Source Info
Oasis maintains and can display many source tables as overlays
to the current image. When a user selects a location on the
sky or region, all of the sources in that region are marked in
their respective tables. With many tables, however, the screen
rapidly becomes too cluttered for this to be effective so Oasis
does not display tables unless asked.
Instead, a special "source info" window pops up. In this window
the user can see all of the information for a single table record
(arranged vertically as field=value pairs rather than horizontally)
and can step forward and backward through this list.
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Data Layer Interaction
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Catalog Table Display
The table retrieved through the catalog search form and controlled using
the Layer Lontrol window is shown at left. The details of how it is
rendered can be set through Layer Control.
When the user selects a location on the display or an area of interest,
the system interrogates all active layers. In this case the area of
interest is being set through an area examination window. Information
about the image for this region is shown, but since the table map layer
is also active, all the sources covered by the circle are also marked
(both on the image and in the table).
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Map Symbol Control
From the Layer Control window, once a table layer has been selected,
the way in which the map is constructed (symbol color, shape, size,
etc. can be specified through this window (brought up through
the "Edit" button on Layer Control).
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Layer Feedback
When the feedback mode is set to area, or when a position is specified (via the
Feedback pulldown or the area examination button) and an area defined,
all layers that are selectable (e.g., the background image and
all active tables) are queried for information. For the image, the
result is area flux statistics (shown at left). For the tables, all
appropriate sources are marked in the table (the highlighted
records in the table above) and on the map (the black and white boxes
overlaying the source symbols on the main window).
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Rescale Overlay Grid
For effiency, the coordinate grid is only computed for the region
of the image which is currently displayed. As the user zooms or
pans, this tool (under the Display menu) allows them to recompute this overlay on demand.
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Active Table Feedback
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NED Basic Data Table
For basic catalog searches, the table cells are simple data
measurements. For other tables, certain cells can represent links to
additional data. In the case of the NED basic source data (shown
at left) some of the columns are encoded in such a way as to indicate
that they are external links, in this case to either the NED detailed
source data or to the ADS abstract server.
Activating either of these links causes a browser to come up and to which
is passed the URL in question. The results for a specific object are
retrieved and displayed.
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NED Detailed Data (Browser)
The NED detailed data for the source highlighted in the above table
is shown at left.
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Data References
Other table references are to additional data files (images, source
catalogs, spectra, etc.). In these cases (based on the MIME
type of the returned information), the data is either added to the
existing display (if an image or source table) or sent to some other
renderer, as in the case of the AAVSO lightcurve shown.
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