TNTatlas Client Help

MERLIN and Other Sample Atlases

Opening an Atlas

Java applet for the TNTclient

Work Area

Work Area Icons

Atlas List

The Atlas List panel occurs only in the standalone client.  You enter the path to the TNTserver with the atlas(es) you want to view, and once connected to the server, you choose the atlas you want to view from those available. You can return to this panel and pick a new atlas or TNTserver for continued viewing.

Layer Controls	The Layer Controls panel lists all the layers and groups for the layout in the atlas presentation area. This list scrolls if the number of groups and/or layers in the layout is large, as it is for the MERLIN atlas. This panel lets you change the visibility of the layers in the display area and expand or collapse the list of layers for individual groups. You can also elect to view metadata for a layer or zoom to its extents using the popup menu for each layer.
	Open Folders		When a layout is first displayed, the folders are automatically open. Clicking on the Open Folder icon for a group removes the listing of individual layers for that group from the Layer Controls panel without affecting whether those layers are visible in the atlas viewing area. The icon changes to the Closed Folder icon.
	Closed Folders		If the folder has been closed, you may click on the Closed Folder icon to provide the list of individual layers for that group in the Layer Controls panel. The icon changes to the Open Folder icon.
	Show/Hide  checkbox		Clicking on the Show / Hide checkbox toggles display of a layer or group on and off. If the checkmark is present, the layer or group will be shown when the atlas viewing area is displaying the corresponding part of the layout. When a layer is shown, it appears in the Legend panel. If the checkmark is absent (box is empty), the layer or group will not be shown in the atlas viewing area and it will not appear in the Legend panel.

The first entry in the layers list is the name of the LEVEL followed by the name of the first GROUP that is part of the level, and then the LAYERS in the first group (if the group folder is open). If there is more than one group, the group name and all of its layers will be listed after the layers of the first group. The number of layers and whether they are hidden or shown is determined by the atlas designer. All layers are listed by default, but you can list only the groups if desired by clicking on the folder icon to the left of the group name. The MERLIN atlas has nearly 50 layers arranged into almost 15 groups at the SPOT and quad grid level for Anne Arundel County, which is the atlas level shown in the Java applet for the TNTclient illustration. Nearly all of these layers are hidden. This design allows for simplicity and speed of initial display. Many atlas users will bypass display of any more detail at this level and navigate straight to the next level. There is no reason to require users to wait for the acquisition of data that they have no desire to view any way.

In addition to the Open/Close Folder icons and the Show/Hide checkboxes, there are popup menus for the layers, groups, and levels (layouts) in the Layer Controls panel. Simply click on the text for the name of a layer, group, or the level as a whole and the appropriate menu will appear. The choices on the layer menu let you view the layer's metadata or zoom to the layer extents in the atlas viewing area. The Metadata on Layer option is dimmed if the layer has no associated metadata. These options are available for all layers whether they are shown or hidden. The group menu lets you show or hide all layers in the group in one step, or zoom to the group extents in the atlas viewing area. The level menu lets you show or hide all groups or expand or collapse all groups in a single step.

Level, Group, and Layer Action Menus

Legend

The Legend panel is a simplified version of the Layer Controls panel. It provides the layer information for currently visible layers only and does not provide the means to alter what is shown. The Layer Control versus Legend Panel illustration, which follows, shows the difference between the Anne Arundel County SPOT level in these two modes. In order to get to the Base Maps group in the Layer Controls, you have to scroll through many other groups. The Base Maps group is all that is shown in the Legend panel because it is the only group with layers turned on for viewing. The Submit button is absent in the Legend panel because you cannot change the layers selected for viewing and, therefore, there is no need to submit requests to the server.

Layer Control versus Legend Panel

InfoTips

InfoTips provide information about the location you click on in the atlas viewing area. Instructions for the use of the InfoTips panel are provided in the lower portion of the panel. InfoTips are set up in the atlas to provide information from a selected database field.

InfoTips Panel

Measurements

The Measurements tools let you make measurements over the displayed geodata that are as accurate as the resolution of the displayed data and your drawing skills. Tools are provided to measure straight line length, curved line length, rectangular area, circular area, and irregular area. Instructions for use of the selected tool are provided at the bottom of the panel. You can also change the units in which the measurements are viewed before or after the measurements are made. There are four length units and six area units from which to choose.

Measurements Panel

Segment	The segment, or straight line, tool reports the distance between its ends. Either end of the tool can be repositioned by dragging when the cursor changes to a crosshair as you near the end of the line. The entire segment is moved when the cursor assumes the 4-point arrow shape.
Polyline	Use the polyline tool to measure any linear distance that is not a straight line between two points. You can either hold the mouse button and drag as you trace along the line you want to measure, or you can click at each vertex of the line. (A vertex is the point where a line changes direction.)
Rectangle	Use the rectangle tool to measure rectangular areas. Clicking on this tool presents an initial rectangle that can be repositioned when the cursor is the four-pointed arrow shape or resized when the cursor is near one of the edges or a corner and the cursor becomes a two-headed arrow.
Circle	Use the circle tool to measure circular areas, such as fields irrigated by center pivot. Clicking on this tool presents an initial circle that can be repositioned when the cursor is the four-pointed arrow shape. You can resize the circle when the cursor is near the edge and is shown as a crosshair.
Polygon	The polygon tool lets you measure irregular areas. It works just like the polyline tool except the start and end of the line are automatically connected (once you have at least three vertices) to enclose an area.
Clear  Measurement	Clicking on the Clear Measurement icon removes the polyline or polygon tool from the atlas viewing area and sets the reported measurements to zero. Use this function to begin measuring another feature in the image. To measure another feature with the segment, rectangle, or circle tool, you reposition and resize the tool. (There is always an initial tool present when you select these latter tools.)

Zoom  the View		Clicking on the Zoom the View icon pops up a menu with the following zoom choices: Full View (entire level layout sized to fit atlas viewing area), Full Resolution (1-to-1 correspondence between screen pixels and raster cells), In 4X, In 2X, Out 4X, Out 2X, and various width specifications in ground distance (1 km, 2 km, 10 km, 1 mi, 2 mi, 10 mi). With these last six choices, the view is zoomed such that a square with sides the distance specified (plus 10%) is fully visible within the viewing area. Thus, if you choose 1 km, an area of the image 1.1 km on a side will be shown plus any additional area needed to fill the atlas viewing area if it is not square. When the viewing area is wider than it is tall, the distance specified (plus 10%) is shown in the vertical dimension, and the horizontal distance will be greater. When the viewing area is taller than it is wide, the distance specified (plus 10%) is shown in the horizontal dimension. Making your selection initiates redisplay of the atlas image in accordance with your choice. As you become familiar with the MERLIN atlas you will recognize that full view is the default setting for the SPOT level (first data level) of the atlas. The image will also be updated to reflect any group or layer hide / unhide actions not yet submitted when you make your zoom selection.
Back up  View	The Back up View icon and popup menu let you return to the previous contents of the viewing area up to 9 views back. Clicking directly on the icon takes you back to the last previous view. Clicking on the arrow to the right of the icon pops up a menu so you can choose the number of views back you want to go. You create a new view each time you submit a request to the server to zoom in or out, unhide or hide layers, scroll, or navigate down or laterally. The last view before the current view is cached in memory for instant redisplay (Undo 1 view). All other steps back require a trip to the server. Only as many Undo options as your number of previous trips to the server are enabled. If you pick an undo option greater than one back, the intermediate undo options are no longer available. Subsequent undo options are available but are renumbered. For example, if you have up to 6 Views that you can undo and you choose Undo 4 Views, there will be two undos left on the list. The image that was originally Undo 5 Views becomes Undo 1 View and what was originally Undo 6 Views is Undo 2 Views. The Undo choices greater than 2 are dimmed. If you now zoom or navigate, what was the current view becomes the 1 view option and the 1 and 2 views options from the last step are now the 2 and 3 views options, respectively. If you click on the Home icon, the Undo list is cleared.
Reload	The Reload icon submits a request for redisplay of the layout in the same position with the current hide / show status of layers. It is equivalent to clicking on the Submit button.
Stop	Clicking on the Stop icon halts any current requests to the TNTserver. The image displayed will be unchanged. If you are waiting on one or more requests and have decided you want to view something else, you can click the Stop icon to end the previous request(s), then submit your new request.
Home	Clicking on the Home icon takes you back to the starting screen of the atlas. The back up list is cleared when you use this function.
Print Image	The Print Image icon lets you print what is currently showing in the atlas image area. There are no printing security issues if you are running the standalone client, and clicking on this icon brings up the standard Windows Printer dialog. If running the TNTclient from your browser, the print function in your browser will not print the Java applet so the Print Image icon is provided in the applet window. However, unless you have enabled printing for other Java applets, you will likely encounter the browser message "Security manager disables printing" the first time you click on the Print Image icon. Printing can be enabled in Microsoft Internet Explorer by choosing Internet Options from the browser's View menu. Click on the Security tab and set the security level for the zone you use for TNTserver to Custom (for expert users). Next click on the Settings button, which becomes active when you choose the Custom security level. Scroll down to the Java entry in the Security Settings list and click on Custom under Java permissions. This action causes a new button to appear at the bottom of the Security Settings window. Click on this new Java Custom Settings button, then on the Edit Permissions tab. Scroll down to Printing and click Enable. Click on OK buttons until all associated windows are closed. If you had launched the applet prior to making these changes, you will need to close it and launch it again before printing is enabled. You cannot print the atlas image area using Netscape Navigator. Netscape Navigator will not print unsigned applets, and currently this Java applet is unsigned. You can also capture the client and current image using the Print Screen key (command-Shift-3 on a Mac), which places the full screen image into the clipboard (a PICT file is created on the Mac).  You can paste this clipboard image or PICT file into a word processor, graphics, or other software package where you can edit the image as desired.

There are three modes of operation for left mouse button actions over the atlas viewing area, which you select by clicking on a mode icon. The mode icons are, from left to right: Navigation, Zoom Box, and Zoom at Selected Point. The currently selected mode is also listed in the field to the right of the mode icons and includes the zoom mode chosen if Zoom at Selected Point is active.

The zoom functions are quite important when using TNTserver because there are two types of atlases: hierarchical and single layout. With hierarchical atlases, you use the Navigation mode to travel through the inverted tree structure. With single layout atlases, you use the zoom modes to reveal new levels of detail that are initially hidden and set to display when you reach a certain map scale. The MERLIN system is a hierarchical atlas. Other hierarchical atlases at MicroImages atlas test site include the Precision Farming and San Francisco atlases. The Nebraska Statewide, NPA World Data Set, and Scotts Bluff County atlases are single layout atlases. The Navigation mode does not display any new levels with a single layout atlas. Instead you get a message that says either "No Child" or "No Navigation," as when you click in an area without links in a hierarchical atlas.

The directional arrows, which are found at the corners and midpoints of the image area, change in color to indicate their current state. If an arrow is gray, the button is disabled, which means there is nothing to scroll to in that direction. If an arrow is blue, it is enabled for use. If the arrow is green, the cursor is paused over the arrow and the client message line shows a DataTip about the arrow's function. If the arrow is yellow, that button is pressed. Five of the eight arrows are active in the following illustration; the arrows along the left edge are inactive because the edge of the map has been reached and there is not another quad map to the east.

Active (left, center) and Inactive (right) Scroll Arrows

The arrows have two functions: scrolling and lateral navigation, which is really just extended scrolling into an adjacent object or layout at the same level of the index. You can tell the function of an arrow when it is enabled (shown in blue) by consulting the DataTip in the client message line when the mouse is paused above the arrow.

A typical DataTip when more of the image is available for viewing in the indicated direction is "Scroll Left and Up" (over the arrow in the upper left corner). You scroll about 90% of the image area when you click on one of these arrows, such that if you scroll left, what was originally seen in the left 10% of the image area is then seen in the right 10% of the image area with a previously unshown area to the left. If you come to the edge of the image before scrolling this far, you will find the image does not shift the full 90% in the indicated direction. If you are at an edge of the image or at Full View, an active arrow indicates there is a lateral link to another object at the same level of the atlas in the direction of the arrow. This direction may be geographic direction or it may be relative position of the link on the parent object.

The DataTip shown in the TNTclient message line when you have reached the edge of a level layout and there is a lateral link tells the direction you will navigate in and provides the description of the object that exists as a lateral link in that direction. A typical example of such a DataTip when the mouse is paused over the middle right arrow is "Navigate Right: Gibson Island USGS Topographic Quad and DOQQ." Clicking on the arrow submits a request to the TNTserver for display of the topographic quad map to the east of the map in the current layout, which will be displayed centered in the image area.

The Atlas Settings window lets you set some parameters to customize the appearance of your client window. The settings apply to the work area panel. Click on the Atlas Settings icon, which is to the right of the mouse mode icons, to change the current font, font size, or the percentage of window width devoted to the work area panel.
 

Atlas Settings window

The Work Area Width determines the percentage of the total Client window width devoted to the work area panel. You can pick from widths in 10 percent increments up to a maximum of 50%. The best width for you depends on a number of factors, but mostly you want to be able to interpret the contents of the Layer Controls or Legend panel without having to scroll horizontally for most entries. If you are making measurements, you'll want the width to be sufficient to view the results without scrolling. Of course, these factors are also affected by font size.

The Font Name choices are Monospaced, Serif, and SansSerif. Your choice applies only to atlas choices in the Atlas List panel and layout, group, and layer names in the Layer Controls and Legend panels. The font used in other panels and for style descriptions in the Layer Controls and Legend panels are controlled by TNTserver. All characters are the same width in a monospaced font. Monospaced fonts are often less attractive than other fonts but the alignment frequently makes sets of numbers more readable. Courier is a common monospaced font. A Serif font is one that has additional lines associated with terminal strokes of a character. A common serif font that is not monospaced is Times New Roman. A SansSerif (literally, without serif) font does not have these character adornments. Helvetica and Arial are common sans serif fonts.

There are six Font Size choices ranging from 8 to 18 pixels in 2 pixel increments. A number of factors will affect the best size for you. A primary factor is your display resolution. The distance you sit from the screen and the amount of information to be displayed are also important.

The three buttons across the bottom of the window are OK, Cancel, and Apply. Clicking OK means you accept the current settings. Clicking Cancel keeps the settings in effect as they were when the Atlas Settings window was opened or after the last time you clicked on Apply. The Apply button lets you see the affect of the current settings without first closing the Atlas Settings window. Thus, you can try out a number of settings and pick the one that is best for you without having to repeatedly open and close the window to see the effect. Remember, the Atlas List,  Layer Controls, or Legend panel must be active to see font settings changes. You can, however, change the active panel after opening the Atlas Settings window.

The Submit button is at the bottom of the Layer Controls and Atlas List (standalone client) work area panels. You can click on the Submit button or on the Reload icon whenever you want to submit changes in the Layer Controls panel to update the image shown. You click on the Submit button in the Atlas List panel to view the atlas highlighted in the list. 

The area for viewing the selected atlas is a function of the dimensions of the client. Resize the window as necessary to provide the desired viewing dimensions. However, the larger the viewing area, the longer the server will take to compute the requested image and send it. The atlas viewing area also contains the scrolling / navigation arrows.

Atlas Viewing Area

You control the area of the image shown and its scale with the icon buttons, mouse click modes, and arrow buttons. You can take the image to Full View (sampled to fit entirely in the image area) and zoom in on the desired area in the Zoom at Selected Point mode. You can zoom out once or twice from 1X View and scroll around to find an area of interest. You can stay in one place (or move around) hiding and unhiding different layers. In short, whatever the atlas designer has made available for viewing, you can get at one way or another in the viewing area. The image shown for the Atlas Viewing Area is obtained by navigating down one level in the MERLIN atlas and choosing to show the composite color DOQQs.

When the cursor is over the viewing area, the client message line will report the georeference system and coordinates for the current cursor position. The coordinates for the center of the image area are reported when the cursor is elsewhere unless some other DataTip is called for.

There is a text field immediately below the atlas viewing area between the Submit button and scale bar that provides the coordinates for the cursor when positioned over the atlas viewing area. Messages concerning communication with the TNTserver and DataTips and HelpTips for the TNTclient appear in a separate message line that extends across the bottom of the TNTclient window.

Cursor Coordinate Line

The message line that runs across the bottom of the TNTclient window (just above the applet warning line if running as an applet from your browser) provides messages concerning communication with the TNTserver and context-sensitive tips for the client as well. The message line has a gray background when the information reported concerns communication with the selected TNTserver. When you pause your cursor over any of the icons in the toolbar,  the arrows in the atlas viewing area, or entries in the Layer Control panel, a ToolTip identifying the function of the button appears in this line with a yellow background. When a mouse click brings up a popup menu, instructions for proceeding (a HelpTip) appear in the client message line with a light blue background. The TNTserver and TNTclient Message Line illustration provides an example of all three message line functions. The DataTip shown in the illustration (yellow background) appears when you pause the mouse over a layer name in the Layer Controls panel and the HelpTip shown (blue background) appears when you click the mouse in the same location.

TNTcient has a scale bar near the bottom to the right of the cursor coordinate line. The default units for the scale bar are meters. You can cycle through the available units by clicking on the scale bar. The units available are meters, feet, kilometers, and miles.

Changing Scale Bar Units

When you are viewing the starting screen of an atlas, for example the San Francisco atlas, you may notice the scale bar reads 0 at both ends, which it will do if the object viewed is not georeferenced or if the scale is such that the minimum scale bar length is less than one of the chosen units.