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Click here for more information about the GLG Map Server.
||The GLG Map Server can render millions
of points in every map requested by the user. This
allows the Map Server to render many vector features such as
roads, populated areas, lakes and rives, shorelines and a
variety of other GIS data with an exceptional level of
The map server automatically switches layers based on the layers' zoom thresholds and the current zoom factor, and it uses a tile cache for faster rendering.
|As the user zooms into an image the vector
data will always appear crisp and precise regardless
of the resolution of the image. The vector data is ideal for
representing elements such as cities, towns, roads and
streets, populated areas, political boundaries, as well as
other landmarks and areas of interests in a map image. A
variety of vector formats are supported.
The image displays the Digital Chart of the World (DCW, VMAP0) vector data overlayed on top of the NASA's Visible Earth raster image.
| A preprocessed Open Street Map (OSM)
dataset is available for use with the GLG Map Server
and can be obtained from Generic Logic. This 100 GB dataset
contains vector data for the whole Earth down to the street
level and buildings details (100 GB). The dataset is
preprocessed into a hierarchical tiled layout for optimum
performance with the Map Server and includes a complete set
of setup files.
|The map server provides support for an unlimited number of layers. Layers are used to group various geographic features so they can be toggled on and off together in the map image. For example, roads and political boundaries are two possible layers. In addition, the attribute matching feature of the map server enables display of only the features inside a layer that have certain attribute values, allowing virtually unlimited customization.|
|A smaller 10 GB US Census/Tiger data set contains
GIS data for the entire US down to the street level details.
It contains vector GIS data for states, counties, roads and
streets, railroads, populated areas and other detailed
The Map Server's label layout negotiation ensures that labels do not obscure each other, and that labels with higher priority are not obscured by less significant labels.
||When vector data is
insufficient or detailed satellite imagery is available for
a specific area, the raster image data may be used.
Raster image data can greatly enhance the look and
sophistication of a map image by providing vivid and
colorful details to compliment the additional vector data
(roads, etc.) overlaid on top of the image. The map server
supports raster image data in a variety of raster image
The image displays the US 0.5m Aerial Images dataset that provides high resolution (0.5 meters per pixel) aerial data for the United States. The dataset is available on per-state basis (approx. 100 GB per state).
|The Map Server can import the NITF and CADRG raster formats,
which are often used for storing scanned maps and chart
images. Setup files for hierarchically tiled datasets may be
generated automatically using provided utilities.
The picture shows an example instance of Command and Control Technologies' C3I Surveillance Toolkit (C3iSTK) providing a Common Operating Picture for tactical surveillance and interdiction. Built with the GLG Toolkit and Map Server, it provides real-time tracking and geo-referencing of targets of interest, as well as point and click control and monitoring for a network of sensor systems. Click here for more CCT application images.
|Elevation data is
a special case of the raster image data which can be used to
display elevation as color-coded
thresholds or shaded
relief image. It may also be used to query
elevation of a particular point on the map. All major
elevation data formats can be imported.
In the picture, the shaded relief image generated from the elevation data in the DEM format is combined with the raster earth image to provide visual elevation feedback. The shaded relief images may be used with both raster and vector datasets.
The NASA's Visible Earth raster data shown in the image are projected on the fly to the orthographic projection to display the globe.
|When the map server is used with the GLG Toolkit, dynamic icons can be
easily added on top of the map display. The Toolkit handles
real-time updates of
icon positions, selecting
icons with the mouse, icon
tooltips, changing icon shapes depending on the
zoom factor and changing icon colors to show icon status.
The map server is integrated into the GLG drawing as a GIS
object, which can be edited with the GLG Graphics Builder
for rapid prototyping.
|The GIS Object may also be
embedded in a bigger GLG application to handle the GIS
portion of the graphics as shown in the second image. It
shows a sample instance of the Command
and Control Technologies' RangeNet control system.
Click here for more CCT application images.
||The NIMA's Digital Chart of
the World (DCW VMap0 / VPF) dataset is a compact (2 GB) dataset
that provides country, shoreline, political boundary, vegetation, roads, railroads
and other data for the whole world.
In the image, the world cities data are displayed on top of the Digital Chart of the World, and the NASA's Visible Earth raster image is used as a background.
||In order to provide a
visually pleasing and flexible look, the GLG Map Server
supports 3 different alpha-blending modes and transparency.
The use of alpha blending in map images can produce visually
appealing transparent and partially opaque effects. For
example, alpha blending can be used to render partially
transparent weather and
cloud maps on top of other vector or raster image
data. Alpha blending can also be used to create transparent
overlays over more important data.
||When merely a simple change
of color is not enough to satisfy the customization needs of
a user, the GLG Map Server provides a unique system of attribute
thresholding. Attributes of vector data can be
automatically changed based on the actual data. For example,
the size and color of a city marker can change based on the
city's population. The label rendered next to the marker can
include the city's name, population, lat/lon coordinates and
any other attributes as shown in the image. Another popular
example is the changing of line width and color of a road
based on its type.
||While many other available
map servers on the market utilize complex relational
databases and intricate setup procedures, the GLG Map Server
provides a sophisticated hierarchical tiling mechanism
for both image and vector data that is easily configured
using ASCII setup files. When tiling is used, the Map Server
loads only the tiles that are required for rendering a
requested map area. The Map Server provides tiling utilities
that may be used to automatically generate setup files for
tiled datasets. The user can easily select which subsets of
data will be used for a particular setup, using aliases to group sets of
layers to be displayed.
The picture shows a tiled raster image with a verbose tile diagnostic output.
||Many map server enabled
applications will need to handle requests on both a global
and small high detail scale. When a requested image
includes raster image data, large amounts of data may be
required in order to fulfill a request encompassing a large
area. In order not to read and process an unnecessary amount
of data, the GLG Map Server provides fallback layer
support. When zoomed out sufficiently, a smaller image can
be used instead of a more detailed one in order to optimize
map server performance.
The GLG Map Server can operate both as a web-based GIS Map Server or stand-alone library API. In the stand-alone mode, the map server can be used as a library linked with a C/C++ program; this mode may be used for real-time applications installed on local machines that want to avoid using an Internet connection to access maps. In the web-based server mode, the map server can be used to provide images to a Java, C/C++/C# or ActiveX clients without a need to install GIS data locally. The web-based map server complies with the OpenGIS standard.
||The GLG Map Server utilizes
its own engine for rendering primitives such as images,
polygons and text. As a result, map images generated on
various platforms are guaranteed to be identical. Also, due
to its independence of the underlying windowing system, the
map server runs on both Unix/Linux
platforms, and can be used on any headless server.