Viewing Window
From JMARS Wiki
The Viewing Window displays the visual information contained in the open layers and consists of two views: the Main View and the Panner View.
- The Main View is the primary display for the visual data contained in the open layers. By adjusting the transparency of the layers in the Layer Manager, multiple layers can be displayed simultaneously. Users can navigate in the Main View by clicking and dragging with the center mouse button.
- The Panning View is a wide-angle view of the area displayed in the Main View and provides the user with a sense of context. Users can navigate in the Panning View by either clicking and dragging with their center mouse button or by left-clicking on the map. Clicking in the Panner view will re-center both the Main and Panning Views on that point.
The Viewing Window also displays numerous parameters of the data being displayed:
- Resolution: The "zoom" of the visual data being displayed is given in units of pixels per degree (ppd) and can be set to a variety of values between 1 and 8192.
- Latitude and Longitude: The Viewing Window gives the latitude and longitude of two different locations. On the top-left of the window, the latitude and longitude of the center of the Main View is given. The user can also navigate to other locations by manually entering the desired values. On the bottom-left of the window, the latitude and longitude of the cursor location is given.
- In both cases, the location is given as East Longitude and North Latitude. West Longitude and South Latitude can be entered either with a negative sign or by specifying "W" or "S" after the numerical value. (Ex: 10 West Longitude can be entered as either "-10", "-10E" or "10W".)
The Viewing Window has many other functions that can be accessed using the menu options at the top of the window.
- Under the "File" Option:
- Save, Save As - saves the current JMARS session to a session file. For more information, see the Session Files wiki page.
- Capture to JPEG, Capture to PNG - takes a screenshot of the current Main View and saves it to a file.
- Exit - exit the JMARS application
- Under the "View" Option
- Layer Manager Checkbox - when checked, the Layer Manager window will be displayed
- Layer Manager Tabs - allows users to "Dock All Tabs" (returned all separated focus panels to the Layer Manager), "Show the Main tab" in the Layer Manager and bring any of the open layers to the front of the layer manager.
- Tool Tips - allows users to enable/disable all mouse tool tips or the tooltips for specific layers that are currently open.
- Navigation - these options give users the ability to jump North, South, East or West and to Zoom In and Out
- Default Time Format - changes the format JMARS uses for displaying times and allows users to specify times according to other spacecraft clocks; for more information of time formats, see the Time Formats wiki page.
- Re-Center the Projection - allows users to re-center the current map projection in the Main and Panning Views. For more information about re-centering projects, see below.
- Under the "Help" Option
- About - displays information about the current JMARS version
- Help - displays the JMARS user's manual
The Viewing Window also gives users the ability to re-project the maps being displayed. By default, JMARS opens with the maps centered and projected at 0E,0N. This means the map will appear correctly proportioned at this point, as well as any point directly east or west of it, but will become distorted at points north and south of it. (This Cylindrical Projection is the same type of projection used to create rectangular maps of the Earth.)
- Re-Center the Projection: Users can re-project the maps with the center of the Viewing Window as the new center-point. This will eliminate any distortion and present the given area as it should really appear. To do so, click on "View" -> "Re-Center Projection" in the Viewing Window.
- Return to the Default Projection: To return the Viewing Window to its default projection, type "0E, 0" into the "Lon,Lat" box and then re-center the projection at that point.
- Below are screenshots of 0E, 80N. The left screenshot is what the location looks like when the map is projected about 0E,0N and the right screenshot is how the location looks when the map is re-projected about 0E,80N. You can see there is much less distortion in the re-projected image.
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