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- What is GIS?
The term Geographical
Information System (GIS) is now used generically for any computer-based
technique for the manipulation of geographical data. GIS is a broad field of
endeavor, and incorporates the related fields of
remote sensing and
photogrammetry, as well as
Global Positioning Systems (GPS).
GIS includes not only hardware and software, but also the special devices used
to manipulate geographic information to conduct spatial analysis and to create
map products, together with communications systems needed to link various
elements.
For more information, check out http://www.gis.com
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- What is Spatial Data?
GIS data is often referred to as “spatial data”
or “digital geospatial data.” The term “geospatial” is derived from “geo”
relating to the Earth, and “spatial” relating to location in space. Two broad categories of spatial data are
known as “vector” and “raster”. Beyond
these main categories, other GIS-related data types include tabular data (database
tables) and image data. All of these are discussed below.
Vector
data layers are
comprised of points, connecting lines and polygons are recorded digitally using
X-Y coordinates. Such images are fully scalable meaning they can be enlarged
and reduced in size for display without sacrificing detail. Most map layers in
GIS are expressed as vector images in order to conserve digital storage space,
accelerate retrieval and minimize work involving analytical processing.
Raster data layers are comprised of picture elements (pixels) that may be assigned a
color value and intensity. An example of such images is a television picture. Raster images
lose resolution (detail) as they are enlarged or reduced in size. These images
usually occupy more storage space than vector images of the same area and
require compression and expansion in use to conserve file space. Raster images
usually result from the scanning process and in GIS are typically used for
digitizing aerial photographs and background maps.
Tabular data, often referred to as attribute data, because it is information that describes the
attributes of features in a data layer, is stored in database tables. Rather than describing location, tabular
data provides the descriptive information about the features in a layer.
Image data or Digital Imagery is stored as
raster data in a GIS and often provides an image as a backdrop to a vector data
layer. Examples of image data include
digital aerial photography, satellite imagery, scanned maps and photographs. Another term for image
data commonly used is digital raster graphics (DRGs). USGS
quadrangle topographic maps are often called
USGS DRGs. Additional information on
image data can be found in the Digital Imagery FAQs.
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- How is NJDEP using GIS to accomplish its mission?
The use of
GIS technology is integral to much of the work done at NJDEP. The use of GIS
technology is the focus of the Bureau of GIS and is now used by many programs
within the Department in order to make better environmental decisions.
Read more about us.
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- What other government agencies are using GIS?
Many agencies at all levels of government are now using
GIS. Check out our Links Page
and/or try performing a Search of the Internet using a browser search engine
(such as Google). Links to other agencies who use GIS are grouped by
Other New Jersey GIS Agencies, those from
States Bordering NJ and
Federal GIS sites.
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- Where can I get information about NJDEP GIS standards?
The NJDEP
has developed GIS standards to assist staff and other users of the Department’s
data. The Mapping and Digital Standards document can be found on the
Standards page.
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- What GIS data has NJDEP made available?
Most of
NJDEP's GIS data is now available for download. The data layers are
available as compressed (zipped) files that contain the GIS data in ESRI
shapefile format
along with metadata (data documentation).
NJDEP GIS Data layers are
organized as follows:
Once the file is downloaded it must be unzipped in order to use the data.
An evaluation version of WinZip is available to download for free at
http://www.winzip.com/
The Departent also has
GPS base station data available.
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- What do I need to use NJDEP GIS data?
Any
GIS software that can read standard ESRI
shapefiles can view NJDEP’s GIS data layers. Staff at the NJDEP use the
ArcGIS suite of GIS software
produced by ESRI, Inc.
However, NJDEP's GIS data can be viewed without
having to purchase GIS software to run locally on a PC. One option is to
download ArcGIS Explorer
from ESRI's web site. When connected to the Internet, ArcGIS Explorer becomes a Web-enabled
client allowing users to perform basic GIS tasks such as: panning and zooming
data layers; displaying data using classifications, symbols, and labels; and
identifying and querying geographic and attribute data.
The second option is to view the ESRI MapObjects
and ArcView powered Internet Map Server applications found on the Interactive Mapping page.
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- Can I redistribute NJDEP data?
The NJDEP requires that permission be obtained prior to
redistributing the Department’s data, and that the NJDEP Data Distribution
policy be adhered to. For details, read the
NJ Data Distribution Agreement
or review the NJDEP Mapping and
Digital Data Standards document.
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- Can NJDEP produce a map for me, or furnish customized data
retrievals from the NJDEP GIS database for my study?
While NJDEP cannot fulfill individual maps
requests, we can provide quality data (on-line) and
interactive mapping applications that
may enable you to produce the information you are looking for.
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- Can anyone make a map online using NJDEP data?
Yes, by using i-MapNJ, NJDEP’s online interactive
mapping application, anyone can use NJDEP GIS data without the need for
downloading specialized software or data layers. i-MapNJ runs in a
browser and can be used to prepare maps you can print on your local printer.
Plenty of online help and tutorials are available so that even those who are
new to GIS should be able to use the i-MapNJ applications.
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- Can I get training for i-MapNJ?
Yes. NJDEP offers i-MapNJ
training classes for the public. Check the i-MapNJ
training page for dates.
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- What other GIS training is available?
NJDEP has made available on the web several
PowerPoint presentations for individuals to access at their convenience.
For other GIS training opportunities take a look at the
GIS Educational and Training links.
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- My DEP Permit Application Form requires NJ State Plane
Coordinates for the location of the subject property. How do I obtain these
coordinates?
This information can be obtained by using the
i-MapNJ DEP interactive mapping application
which displays NJ State Plane map coordinates at the lower left-hand corner of
the screen:
In this example, Map: 400482.11, 563650.06 denotes NJ
State Plane Coordinates in feet. The
first number is the X-coordinate (the easting) and the second number is the
Y-coordinate (the northing). In order to be confident in the accuracy of the
coordinates at the mouse cursor, you should zoom-in close enough that the
location can be easily identified using the aerial photography and other base
map layers.
If you prefer, you can also telephone the GIS Help Desk at 609-777-0672 to obtain
this information.
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- Where may I find historical aerial photography, base maps,
etc.?
Historical aerial photography (not in digital
form) can be viewed at the NJDEP Tidelands Management Program aerial photo
library. Appointments can be made by calling 609-292-2573. For information on
New Jersey base maps, view the GIS Technical Mapping Standards document and/or
visit the NJDEP
Maps & Publications web site.
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- What are map projections and coordinate systems and why are
they important?
All geographic data
layers store locations in a particular
map projection or
coordinate system. Map projections and coordinate systems are important
because, in order for data layers to overlay correctly, they must be stored in
the same system. Examples of coordinate systems include
Latitude and Longitude,
Universal Transverse Mercator (UTM), and NJ State Plane. These systems relate to the
way locations on the Earth are stored in a data layer, and the need to make
adjustments when translating locations from a sphere-shaped Earth to a flat
map.
Additional information
on map projections and coordinate systems is available at the
USGS Map Projections web site.
Information on the
NJ State Plane system can be found in the
NJDEP GIS Digital Data Standards document.
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- Where may I obtain a coordinate conversion utility?
The
New Jersey Geological Survey provides a
coordinate conversion utility for
converting coordinates from Latitude/Longitude to NJ State Plane feet and visa
versa.
The US Army Corps of Engineers'
Corpscon utility also allows coordinate conversions but has more input and output
options and will handle datum conversions as well. The Corpscon utility along with other software
is available for free download at the web site of the
National Geodetic Survey (NGS).
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- The i-MapNJ application isn't responding when I ask it a question. What is the problem?
It could be that you have a Pop-up blocker turned on. To momentarily bypass the effects
of Pop-up Blocker where it would otherwise conflict with the operation of i-MapNJ, hold down the [ctrl] key
on your keyboard as you click on the desired function (Find or Identify, etc.). If you're using
Internet Explorer, you can turn off Pop-up blocker by going to the Tools menu and selecting Pop-up Blocker > Turn Off Pop-up Blocker.
Remember if you load Google.Earth or Yahoo (or any other tool bars) they have Pop-up blockers on as the default and these
must be turned off. If this does not work for you, please contact the GIS Help Desk at (609) 777-0672 for assistance.
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