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Click on thumbnails to see bigger images.
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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 details. 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. |
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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. |
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The US
Census/Tiger data
set contains
a
complete set of 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 information. 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. |
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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
formats. The NASA's Visible Earth raster data shown in the image are projected on the fly to the orthographic projection to display the globe. |
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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. |
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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. |
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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. |
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The NIMA's
Digital Chart
of the World
(VMap0,1,2 / VPF)
data sets provides GIS
information for the whole world and contains
GIS
data for countries, provinces, cities and populated areas, road and
rail
roads, bodies of water and other details. 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. |
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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. |
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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. |
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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. |
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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. |
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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. |
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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.
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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 and Windows platforms, and can be used
on any headless
server. |
