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GIS Defined

A Geographic Information System (GIS) is a system for capturing and manipulating data relating to the Earth. A common use of GIS is to overlay several types of layers (for example, aerials, elevation data, street maps) to analyize useful data about a given geographic area. Geographic data combines and links graphic representations of "features", or "events" found on the earth with corresponding tabular data, which is also called attribute data.

The advantages of digital versus analogue data
are outlined in the table below:

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Imagine you have to keep track of pruning a tree. How would you keep track of and communicate information about this tree to other people so they know the tree has been pruned? You might use a database to keep track of what species it is, if it was pruned, what year it was pruned, how old it is, how tall it is, how healthy it is, and any other attributes that are important. This tree is one record in a database. We call each category (i.e. tree type) a field. Now imagine a whole street or development of trees that you need to keep track of attributes for. Because we are now dealing with more than one tree, it becomes relevant where each tree is so we know what information relates to which tree. We map the location of each tree and identify which attributes belong to which tree and sometimes color code the map based upon these attributes. This is the foundation of GIS. A GIS tells us where something is and what it is. Computers are synonymous with GIS, and using a computer we can have hundreds of fields (different attributes) for millions of records (trees).

You will be able to examine the attributes of features as you navigate NORM maps.

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We can also have other layers of information in our GIS. Our information on trees would constitute one layer of information. We could also have a layer with streets and a layer with property lines. Any information can be represented as a layer. Each layer is represented by a different graphical type feature & table. Vector layers represent features in one of several ways:

Points: A point is good for representing information in which it is necessary to show where a feature is, but its physical shape is not important (i.e. trees in the old growth tree layer). Lines: A line is suitable to represent many real world features (i.e. the streets in the street layer). Polygons: Don't be intimidated by the name. It is really just a solid multi-sided shape. When you see a polygon, remember that everything inside the boundary has the attributes associated with the record. (i.e. parcel numbers in the property layer) You might hear people talk about coverages, themes, or shapefiles. All these terms are other names for layers of information. With individual layers we can conduct analysis between layers and only display layers of interest. Data for GIS applications can include: Scanned or Digitized Data Databases GPS field sampling of attributes remote sensing and aerial photography

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Metadata is the Who, What, When, Why, & Where of GIS. This step documents the work done and the reasons behind the methodlogy of collection so others may use the data appropriately. For example, a person might create street data for a statewide inventory with an accuracy level of +/- 100'. This data created with this accuracy is appropriate for this study because the margin of error is marginal on a statewide level. What Metadata includes: With metadata, a user can quickly asses the data and determine is it is appropriate for use in their project. Who created the data? What type of data is it? When was the data created? Why was it created? For what purpose? Is there any copywrite issues? And where is the data stored?

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What can a GIS do?

Who uses GIS?

Web based GIS

GIS on the Web is an inexpensive method for reaching a vast audience. In addition, the easy-to-use browser-based format lets anyone use the Web to access maps and GIS-based data--sophisticated GIS applications become usable by everyone over the Internet. Applications for web mapping & web GIS: Ranger/First Responder Maps Trail Guides Birding Locations Geo-caching Natural Resource Management Property Acquisition PR, Education & Outreach… Back to Top Understanding the NORM web map viewer All web browsers involve a few symilar items. A Mapping Window Tools to manuver around the mapping window A Legend A way to querry the information Toggle Toggle Live Legend Select this tool to toggle between the folder view of the legend and a static legend of the current map. Overview Map Toggle Select this tool to toggle on and off the Overview Map (located in the upper left hand corner of the map). Pan and Zoom Zoom in [DEFAULT BUTTON] Zoom in to a specific location on the map. Use the mouse to either select on the map where to zoom in (by single clicking onto the map) or drag a rectangle around the area to zoom in. Zoom out Zoom out from a specific location on the map. Use the mouse to either select on the map where to zoom in (by single clicking onto the map) or drag a rectangle around the area to zoom out from. Full View Zooms out to the full viewing area (the 4 counties of Phase 1 study area). Zoom Previous Zooms to the previous views (10 previous views maximum). Zoom Forward Undo for the Zoom Previous (10 previous views maximum). Pan Move (re-center) the map. Click on the map, hold down the button and move the map into the direction desired or, for slight pans, click onto the map to re-center to that point. Map Features Identify Gets information about ONE specific layer's features on the map. Before using this tool, select the LAYER by clicking onto the layer name in the legend list on the right - you might have to open up the folders to view the layer you want. Then click the item on the map that you want information about. Identify All Gets information about ALL Layer's features on the map. Click the location on the map that you want information about. A pop up window will display the information about all the layers (you may have to scroll through other layers to get your information). Make sure that your browser has popups enabled. Query Selects items from the selected layer based upon selected criteria. Before using this tool, select the LAYER by clicking onto the layer name in the legend list on the right - you might have to open up the folders to view the layer you want, also zoom in until you see the layer you want to query. Then, click the query tool, a menu will show up at the bottom of the map - displacing the legend (you can click "Legend in Another Window" to view the legend). Select your query criteria - make sure you click "Add to Query String" and then "Execute". A table is shown displaying your selections. You may zoom to each record, or select "Zoom to these records" to zoom to all selected (by default the map will zoom to all queried items). Find Will search the entire database of layer to find case-sensitive material. Before using this tool, select the LAYER by clicking onto the layer name in the legend list on the right - you might have to open up the folders to view the layer you want, also zoom in until you see the layer you want to use Find for. Then, click the Find tool, a box will show up at the bottom of the map - displacing the legend (you can click "Legend in Another Window" to view the legend). Select your find criteria - then click "Find String". A table is shown displaying your selections. You may zoom to each record, or select "Zoom to these records" to zoom to all selected (by default the map will zoom to all queried items). Measure Use this tool to draw on map and measure what you drew. Measurements are calculated in total feet, segment feet and square feet. Lines do not print. Select by Rectangle Use this tool to select multiple items in a specific layer. Before using this tool, select the LAYER by clicking onto the layer name in the legend list on the right - you might have to open up the folders to view the layer you want, also zoom in until you see the layer you want to use Select for. Then, click the Select by Rectangle tool and with your mouse, draw a box containing the items you want information about. A table is shown displaying your selections displacing the legend (you can click "Legend in Another Window" to view the legend). You may zoom to each record (by clicking the Rec #), or select "Zoom to these records" to zoom to all selected (by default the map will zoom to all selected items). Select by Line Use this tool to select multiple items in a specific layer. Before using this tool, select the LAYER by clicking onto the layer name in the legend list on the right - you might have to open up the folders to view the layer you want, also zoom in until you see the layer you want to use Select for. Then, click the Select by Line tool and with your mouse, draw a line passing through the items you want information about. A table is shown displaying your selections displacing the legend (you can click "Legend in Another Window" to view the legend). You may zoom to each record (by clicking the Rec #), or select "Zoom to these records" to zoom to all selected (by default the map will zoom to all selected items). Clear Selection Clears the selected features highlighted in color on the map and listed in the table. Printing Print Opens a page for printing the map with a general map title and legend. Print to Scale Opens a dialog box displacing the legend (you can click "Legend in Another Window" to view the legend) that enables you to create a preformatted page as a pdf, tif, jpg, or Illustrator file at either a specific resolution or scale. Select the type of file, DPI or Scale (in feet) then click the Create Layout button. A link will be displayed enabling you to download your print. Book Marks Save Bookmark Enables a user to save (via your computer's cookies) the view extent of the map. Then using the Open bookmark tool, the user can return to that saved map. Open Bookmark Enables a user to open (via your computer's cookies & popup window) saved bookmarked views. You can also delete bookmarks in this window. Help Help Opens the tutorial for NORM. This tool list is at the bottom of page.