DeLorme Professional Weblog

XMap’s data synchronization tool was designed to facilitate the transfer of GIS layers from a central Enterprise database to multiple XMap users. Typically these users spend a lot of their time away from the office without continual access to their corporate network so they need a local database whose contents match the Enterprise version.

Setting up synchronization involves the establishment of a connection between each user’s local database and the central database within which all of the layers are stored. This connection is initiated through the distribution of a simple executable file that is created by the GIS manager using XMap’s Database Manager. The assignment of the required layers for each individual or group is determined using simple check boxes and can be updated or modified at any time.

For most GIS managers, providing access to data means allowing these field workers to view the required data layers on their version of XMap; to turn on or off layers as needed; to uncover all of the attributes pertaining to each object in a layer; and, if necessary, to submit notes or redline corrections using the same synchronization process. More often than not, protecting the integrity of the data is paramount, so the idea of enabling remote data editing is one that requires careful consideration.

There are several features within XMap that can be employed to allow remote data editing:

Check-out/in
Initiated by the GIS manager, this tool is used to copy a geographic subset of a layer and assign it to another XMap user for the purpose of remote editing. During the time that the selected area is checked out, the corresponding area in the original layer is locked for further editing. After the edits are complete, the modified data is checked in and the remote edits are applied to the master layer.

Redlining
As previously mentioned, redlining is an integral component of the synchronization process and was developed to allow field observations to be annotated and submitted to a GIS manager. It can also be applied as a tool for geometric data collection because any of the lines, points, or polygons that are created and submitted as part of a redline layer can be appended to the original GIS layer by the GIS manager using the Draw tab’s Copy to… GIS Layer function.

XMap Forms
XMap’s innovative GIS data collection tool allows point data and any accompanying attributes to be collected or edited using a handheld Earthmate PN-Series GPS receiver or using the Professional version of XMap via synchronization. Utilized in this way, XMap Professional is transformed from being a data viewing tool to one that allows direct input into the contents of central GIS database.

Synchronizing to XMap GIS Editor
The normal implementation of the XMap synchronization process automatically creates a locked database on the recipient’s computer. Control over the content of this database is administered by the Enterprise manager both in terms of the availability of specific layers and the editing or updating of features in that layer. For the majority of organizations or companies utilizing synchronization, this workflow offers the best approach as it simplifies the distribution process and eliminates the possibility of someone in the field inadvertently modifying elements of the data and, though synchronization, applying these edits to the central database.

Nonetheless, there are occasions when individual XMap users need to collaborate on the updating of certain GIS layers but are unable to concurrently access the same database. Often the accepted solution in these cases is to export a copy of the layer or layers in question, import a copy into each remote user’s version of XMap, and work independently. The challenge in this approach is manually appending all of the updates into a single layer after the editing process is complete.

A more workable solution to this problem is to set up synchronization with each user given access to a single master database. Instead of assigning the customary role of XMap User to each subscriber, those tasked with remote editing are assigned the role of XMap Administrator. As with the conventional synchronization process, layers can be individually selected for each subscriber or group. A subscription file, typically distributed through email, transfers this database role to each user and enables the synchronization tools in the recipient’s version of XMap.

The first thing that the subscriber with elevated editing privileges will notice is the absence of the lock icon next to each record in the attribute table, which for XMap User level synchronizers, indicates that the layer is for viewing only. Using either the Editor or Enterprise versions of XMap, the geometry and the attributes of the subscribed layers are available for editing or new records can be added. After reconnecting to the corporate network on which the Enterprise database resides, the synchronization button in the toolbar is clicked to automatically apply the edits to the master layer.

There are a few considerations that that should be taken into account before adopting this concurrent editing workflow, especially if multiple XMap users are involved.

• All remote edits are applied to the master database after editing, so if is an object is deleted remotely, it will be deleted from the original as well.
• If more than one XMap user modifies a specific object, the changes made by the last one to synchronize will be applied to master database. For example, if subscriber A and B are both remotely editing the same layer and subscriber A deletes a record and clicks the Synchronize button, the object will be removed from the master layer. If subscriber B alters the same object by either moving it or editing one or more of the attributes and synchronizes after subscriber A, the object will be added back into the layer in its new location or with updated attributes.
• Synchronization is initiated by the subscriber, not by the GIS manager so unlike the check-out/in process, there is no way to review the modified layer before its changes are applied to the master layer.

XMap’s synchronization process optimizes the distribution of GIS data across a remote workforce and ensures that every subscriber has access to the latest version of all applicable layers. By assigning an appropriate role to specific XMap GIS Editor users, it also serves as a powerful collaboration tool allowing simultaneous editing of selected layers and automatic integration of these edits into a single database.

While it is conceivable that one could effectively employ XMap without ever clicking the Draw tab, the Route tab, or even the GIS tab, it is implausible that anyone could operate the software in a productive manner without addressing Map Data. In short, Map Data is the essential tab. At a superficial level, it is a fairly straightforward component of XMap, its primary function being to allow a map view to be saved for later retrieval. That said, there are a number of less obvious features that can allow you to do some very interesting things within the Map Data tab.

Dual Map Display
Perhaps the dual map display is one of the more obvious features of the Map Data tab, but it is a very powerful function nonetheless. The two separate windows in the tab area provide an opportunity for the contents of both the primary and secondary maps to be customized. For instance, you can display imagery on one side and the topographic map data in the adjacent window by simply selecting or clearing the appropriate check boxes next to each dataset. The dual map windows can also be used to render maps at different zoom levels, simultaneously providing a local map and a regional perspective.

Customizing the Contour Interval
The contour interval, as represented on the Control Panel to the right of the map window in XMap, is the difference in elevation between adjacent contour lines on the map. Contours are generated dynamically and the interval decreases as the map display is zoomed. For example, at data zoom level 11, the contour interval is 100 feet while at level 14, it is 20 feet. This ensures that the concentration of contours is appropriate for each display level or scale. There are occasions when the contour interval at certain zoom levels might need to be adjusted. For instance, in a mountainous area, the contour interval may need to be increased to unclutter the map, while in a lowland area you might choose to space the contours closer together to emphasize the terrain.

The contour interval can be adjusted using the following procedure:

• In the Primary Map window in the Map Data tab, click the plus sign next to Reference Data and then click the plus sign next to Topography.
• Right-click Contours and select Properties
• The resulting dialog box offers a drop-down list from which Default, High Density, Low Density, or Custom can be selected. High Density decreases the contour interval across all zoom levels; Low Density increases the interval; while custom allows the precise spacing at each zoom level to be manually configured.
• If Custom is selected, the next window in the sequence provides the opportunity to determine the contour units in feet or meters, the number of major (labeled) contours per minor, and the overall contour spacing for each selected zoom level range.
• After clicking Next again, you can adjust the overall zoom level range within which contours will appear on the map by sliding the arrows back and forth.
• Finally, you can select the map windows in which contours will be displayed before clicking the Finish button.

Note that a custom contour configuration is saved as a component of the current XMap project, which ensures that you will not need to repeat this process each time you use XMap. In fact, if you need to continually adjust the contour interval, it is a good idea to establish several contour configurations and save each as its own project file.

Adjusting the Shaded Relief Pattern
XMap’s topographic shaded relief provides a shadow effect derived from the underlying digital elevation model that visually enhances the terrain on the map. By default, this shadow effect is based on a hypothetical light source emitting from the northwest at an inclination of 40° above the horizon.

In the Map Data tab, Shaded Relief is listed under the Topography section of the Reference Data, just below Contours, which was described above. Accessing the properties of the shaded relief pattern using the same right-click process as before offers the ability to adjust the bearing of the light source, the inclination value, and the brightness of the shadow effect. For example, you could display a map showing the terrain at sunrise by changing the bearing value to E (for east).

Raster Layering
A raster map is one that is represented by an array of different colored pixels, the same as in a conventional digital photograph. A vector map is made up of geometrical points, lines, and polygons which are used to represent geographic objects stored in a database. The XMap North America Topographic Data is an example of a vector map dataset.

When displayed in XMap, raster map layers, such as aerial imagery or scanned USGS quad maps, will appear on top of the corresponding vector map, which usually obliterates the view of the vector features. The Map Data tab in XMap offers a way to adjust this layering hierarchy so features such as roads or contours can be rendered on top of a raster layer.

Follow these steps to adjust the layering properties of a raster layer:

• In the Map Data tab, click the plus sign next to the appropriate data type (for example, Color Aerial Imagery) and then click the plus sign next to specific file name. This will reveal the format of the raster layer (such as Color DOQQ).
• Right-click this data format name and select Properties. Usually the first dialog box offers the option to select a transparent color. It is usually not necessary to adjust this setting.
• The next dialog box is used to adjust the layering of the selected raster layer relative to the underlying vector dataset. From the Raster Data Position drop-down list, select the component of the vector data that you want to display on top of the raster layer (such as roads). Note that whatever feature is selected, each of the items above it in the list will also be pushed to the top of the layering hierarchy. Make sure to click the Add/Change button before proceeding.
• It is possible to establish a different layering sequence for selected zoom level ranges. For example, the Raster Data Position setting could be configured in such a way as to display just the aerial imagery until data zoom level 15 and overlay the roads from levels 16 to 20.
• Click the Next button to set the data zoom level range within which the selected raster layer will appear and click Next again to determine which map windows will display this data.
• Finally, if your current project contains more than one instance of the selected data type, you will be prompted to configure each of these raster datasets with the same parameters in the selected layer.

This raster layering process is often used in conjunction with the Map Features function in the Options area of XMap to simultaneously filter the display of vector features and overlay this modified data on an aerial image.

Displaying a Coordinate Grid
Reading this article, you will have noticed that most of the configuration options in the Map Data tab are accessed by opening the properties dialog box for each component. The coordinate grid function continues this trend. By default, grids are not displayed in XMap; however, they can be turned on from within the Map Features tab in the Options window or using the check box next to Grid Lines in the Map Data tab. The grid lines feature is accessed by clicking the plus sign next to Reference Data and then clicking the plus sign next to Grids and Zones.

By right-clicking Grid Lines and selecting Properties, you can adjust the data zoom level range within which the coordinate grid will appear as well as the map window within which the grid will be displayed. Latitude and Longitude is the default format; however, UTM, State Plane, the Military Grid, or the U.S. National Grid can be selected from the Display tab in the Options area of XMap.

All of the datasets listed in the Map Data tab can be customized in certain ways. By selecting the properties option while right-clicking a particular layer or feature, you can often create a thoroughly unique map that accentuates the display of whatever data layers you have imported or created in XMap.

It has been estimated that 10,000 miles of new roads are added each year in the U.S. That’s an average of nearly 30 miles of pavement per day! Because of this, ensuring that maps are up-to-date is a constant challenge for any map publisher or spatial data management company. Immediately after a product is released, work must begin on the next version.

As is evident in the 2011 release of the XMap North America Topographic Data, DeLorme’s data management team produces a remarkably thorough, accurate, and up-to-date database of roads and other geographic features; however, it is inevitable that there will be roads that are not included in the base map database. This might be because a new subdivision or neighborhood has just been added; the roads in question are not publicly maintained, such as those in industrial facilities or private developments; or the road in question happens to be your driveway.

Several years ago, DeLorme software engineers developed a tool that has become a key component of all Delorme software products, including the current versions of XMap. The Routable Road tool allows you to create your own searchable and routable road networks that are integrated with the vector base map. This feature is accessed from the Draw tab and all of the roads that are created are stored within a Road Layer that can be easily shared with other XMap users.

There are several methods for adding new roads in XMap:

Freehand Road Creation
After selecting the Routable Road tool, type a name for your new road in the Road Name field and position your cursor at the point on an existing road where the new road begins. A yellow diamond will indicate that the road will be snapped to that point. Either draw the new road in freehand form by clicking and holding with your left mouse button or click repeatedly to create shape points that define the alignment of the road. If the end of the new road intersects with an existing road, position the final shape point at the point of intersection, look for the yellow diamond as before, and either double-click the map or click the Done button on the Draw tab.

You can also use this freehand method to trace a road from an aerial image or raster topographic map. In this case, use the secondary map window to display this reference map while the primary map shows just the existing roads to ensure that connectivity is established.

Creating Roads using Coordinate Geometry Input
This method of road creation ensures that the precise dimensions of the road can be transferred from some source information into XMap. After selecting the Routable Road tool and clicking the point of origin for the new road on the map, select the Distance and Bearing (or Angle) option and type the appropriate values. Repeat this process for each line segment and, when finished, click the Apply button.

Creating Roads from a GPS Log or Track File
The most accurate method for creating new roads is to drive along the road while recording a GPS track or log file. This file can then be converted into a routable road in XMap. Track files are recorded using a handheld GPS receiver, such as the PN-Series receivers from DeLorme, while log files are generated within XMap. In either case, it is a good idea to disable the default logging or tracking function on the device or in the software until you reach the starting point of the new road. As you begin to drive along the new road, enable the logging or tracking function and stop recording and save the file when you reach the end of the road. This ensures that the log or track is limited to the required road segment.

Before creating a road from a track, the track file must be downloaded from the handheld GPS device using XMap’s Exchange function. After this is complete, each individual track will be listed in the File area of the Draw tab. To convert a selected track to a routable road, right-click the track name and select either Copy To or Move To and choose an available road layer. If this option is not available, click the New button to the right of the tab area to create a road layer.

A GPS log file is generated by XMap when a GPS receiver is connected to the computer, GPS is activated, and logging is enabled. Log file recording, and playback functions are accessible by clicking the GPS Log button in the GPS tab. To convert a recorded file into a routable road, click the File button in the Draw tab, click import, and browse to the GPSlogs folder in your DeLorme Docs folder. Make sure to select Road under the Save as Type drop-down list.

To ensure that roads created from GPS data are connected and therefore routable, click the Select button in the draw tab and move the first and/or last shape point so it snaps to an existing line.

Creating Roads from Third Party Files such as Shapefiles
Any linear object in XMap, whether it is included in the base map dataset or imported as a GIS layer, can be easily converted into a draw object and then copied or moved to a road layer as outlined above. You can then use this function to create routable roads from any data format supported by XMap.

After importing the required layer, simply right-click the line object, select Manage Draw and choose Copy to Draw Object.

Sharing Road Layers with other XMap Users
As with other draw objects, roads are stored in an .an1 file that is saved in the Draw folder in your DeLorme Docs folder. To send your road updates to another XMap user, simply attach this file to an email. Upon receiving the .an1 file, the recipient can display the new roads by adding the .an1 layer to their current project using the Data > Add… function in the Map Data tab.
An alternative to the manual .an1 file transfer process is to create a transfer file in the Map Data tab and send this to other XMap users. This function creates an identical version of your XMap project in the recipient’s copy of XMap, allowing you to simultaneously send multiple layers and to stipulate a specific zoom level and map center location.

In a connected environment, it is also possible to store the roads layer on a server and have each XMap user view this one copy. This ensures that everyone has access to the latest road updates as they are added by the administrator. In this situation, it is crucial that only one person is tasked with updating the layer. Simultaneous edits by multiple users will inevitably lead to problems with new edits overriding older changes.

The Routable Road tool enhances the functions of XMap in many ways:

• When viewing a map onscreen or after sending the map to a printer, the added road looks identical to those in the original base-map—even its label looks the same.
• You can search for added roads by name using either the QuickSearch or Advanced Search options in the Find tab.
• You can use added roads to create a route, and, if tracking with GPS, the road name will be included in the onscreen and spoken directions.
• An address database imported using XMap’s geocoding functionality will correctly place the appropriate points on an added road.

Even for novice users, the Routable Road tool significantly alters the focus of the software by transforming it from simply a map-viewing application to a map-making one. Additionally, it offers a means to ensure that your version of the XMap base map data is as current as it can be.

XMap users run the gamut, from large corporations to standalone GIS enthusiasts. The former usually have a well structured I.T. infrastructure to facilitate the central management and distribution of data. The latter don’t need to concern themselves about central data management; their data is locally managed by the SQL server conveniently installed on their hard drive during the installation of XMap.

The target of this article is for those XMap users who fall somewhere in the middle: organizations that are large enough to realize the importance of sharing data among their workforce but small enough to get away with not hiring a full-time I.T. manager. Judging by the calls that are received by XMap technical support and product specialists, this group represents a sizable percentage of XMap users.

Sharing GIS data often involves the simple act of exporting, delivering, and subsequently importing Openspace layers. Under this scenario, each user of XMap is their own data manager and their local version of SQL acts as a single-user data repository.

While the export/import process is a reasonably effective data distribution solution in situations where data is shared on an occasional basis, it does have its limitations and potential drawbacks if layers are continually changing hands:

• It is time-consuming and inefficient
• It requires the action of the data host to physically extract the data; if that person is unavailable, others cannot access the data
• Multiple versions of a particular layer might accumulate in each user’s database causing confusion and possible storage capacity issues
• Most importantly, edits made by each individual user will not be reflected in other users’ versions of the layer

An obvious solution is to develop a more collaborative working environment in which a single version of each layer is maintained and updated in a universally accessible location. A prerequisite for developing this type of data management model is to have all of the required users on some sort of network. This network does not have to be overly complex and for small organizations, it can be easily set up using off-the-shelf hardware.

Once the network has been established and the required users have been granted the appropriate access, a shared XMap database can be created. For this process, there are two possible approaches:

• All users can be given access to an existing XMap database on an individual’s computer
• A new instance of Microsoft SQL can be installed on a dedicated computer or server.

The benefit of the first option is that no additional hardware needs to be purchased and no additional databases need to be built and maintained. The shortcoming of this approach is that it doesn’t solve the problem of accessing data when the owner of the host database is away from the office.

If it is feasible, dedicating a continually accessible computer to act as a central SQL server is a much better approach. How is this instance of SQL installed and how is the requisite XMap database created? Thankfully this part is easy.

As previously mentioned, all versions of XMap include by default, an instance of Microsoft SQL on the same hard drive on which the software was installed. During the installation process, SQL is installed before XMap itself. This version of SQL is freely distributed by Microsoft so there is no limitation or license restriction applied to its distribution. Therefore, the simplest way to install SQL on the server is to insert the XMap disc in an available DVD drive and allow the installer to run the prerequisites. After a few minutes, the installer will ask for an XMap license number at which point, the installation can be terminated using the Cancel button. The XMap-ready instance of SQL remains, in spite of the fact that the software itself was not installed.

Using any connected version of XMap, a database can now be created and access granted to all XMap users. The simplest way to create a database on this new server is to create, import, or copy an existing layer. Instead of adding the layer to a local database, choose New under the Target Database dropdown list, type the name of the server (usually [computer name]\XMap7) and type a database name.

Other XMap users can then access the layers in this database by selecting Manage from the Layers menu in the GIS tab and choosing Other from the Source Database dropdown list. After typing the server name as noted above and clicking the Connect button, a list of available databases on the server will be displayed. Back in the Manage Layers window, the available layers can now be added to the Workspace.

This collaborative environment requires a certain level of workflow management to ensure that multiple users are not trying to simultaneously edit the same records. In such cases, the edits performed by the last user to click the Commit button will be the ones applied to the layer. Thankfully XMap includes several tools to help administer this workflow process.

The Database Manager, which is accessed from a button in the Workspace in XMap, allows the administrator to offer database permissions and assign roles (Server User, Database Creator, or Server Administrator) to each user. It can also be used to initiate the database synchronization process that allows GIS layers to be automatically delivered to the local database on each user’s computer so they can work in a disconnected environment.

The layer Check-out/in process can be utilized to assign data within a specified geographic area to an individual user who can subsequently edit, add, or delete records within the limits of that area. While this data is checked-out, the corresponding area in the original layer is locked for editing ensuring that multi-user concurrent editing is avoided.

If an individual user simply wants a copy of a centrally stored layer to work on independently or to take into the field, the easiest way to achieve this is to create a duplicate version of the layer in a local database. To do this, select the required layer in the Workspace, click the Layers button, click Create, and choose Copy Layer. In the resulting window, make sure the local database is selected from the Target Database dropdown list.

Setting up a shared working environment is not a difficult process for small companies or organizations. For XMap users, the benefit of being able to effectively share data and centrally administer key GIS layers results in a more efficient workflow.

For more detailed information on XMap from the I.T. perspective, read the XMap Admin Guide.