source: main/adopters/nj/branches/3.0/src/main/webapps/doh-shad-content/xml/html_content/home/MapDownloadJSON.xml @ 25268

Last change on this file since 25268 was 25268, checked in by GarthBraithwaite_STG, 3 months ago

nj - s&r view requests to content file. Cleaned out 2.3 content dirs. added 2.3 _topic.css as a temp solution for home page icon formatting.

File size: 4.5 KB
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1<?xml version="1.0" encoding="ISO-8859-1"?>
2
3<HTML_CONTENT xmlns:ibis="http://www.ibisph.org">
4
5        <ibis:doc>
6                <name>resource/MapDownloadJSON</name>
7                <summary>Page describing process for downloading map data, geojson, and using it in ESRI products</summary>
8        </ibis:doc>
9
10
11        <TITLE>Downloading and Using GIS</TITLE>
12        <CONTENT>
13                <br/>   
14                <h2>Downloading GIS data from NJSHAD</h2>
15                <ul>
16                        <li>To download GIS data from NJSHAD, first create a query that produces a map. In the upper right-hand corner
17                        of the map view, open the "Layers Control" menu <img src="contentfile/image/home/layers.png" 
18                        title="Layers Control icon" alt="NJSHAD Map Layers Control icon"/> if it is closed.
19                        A blue "Download Layer" button <img src="contentfile/image/icon/16/download_blue-box.png" title="Download Layer icon" 
20                        alt="NJSHAD Map Download Layer icon"/>  will be visible next to the map layers that are available for download.<br/><br/></li>
21                       
22                        <li>Clicking the 'Download' button opens another browser window displaying a wall of text. This text constitutes
23                        an array of feature definitions and coordinates that make up a GeoJSON file. GeoJSON is an open-source
24                        geospatial data interchange format based on JavaScript Object Notation (JSON).<br/><br/></li>
25                       
26                        <li>To save the GeoJSON text as a file, right-click and choose Save As...<br/><br/></li>
27                       
28                        <li>The resulting .json file can be viewed and manipulated in GIS desktop software. ESRI's ArcMap is a widely
29                        used product, and the free, open-source program QGIS is another popular choice. Slightly different procedures
30                        are necessary to use a GeoJSON file with these programs.<br/><br/></li>
31                </ul>
32
33                <h2>Using a GeoJSON in ESRI ArcMap</h2>
34                <ul>
35                        <li>GeoJSON files from NJSHAD cannot be directly opened in ArcMap; they must first be transformed into the ESRI
36                        shapefile format (.shp). Several options are available, but one easy method to transform GeoJSON files into
37                        shapefiles is to use the free, open-source, on-line transformation tool available here:
38                        <a href="http://ogre.adc4gis.com/" target="_blank">http://ogre.adc4gis.com/</a>.<br/><br/></li>
39
40                        <li>Copy and paste the entirety of the .json text into the interface window. Download and unzip the resulting
41                        shapefile to your directory of choice, and load into ArcMap as usual.<br/><br/></li>
42                </ul>   
43               
44                <h2>Using a GeoJSON in QGIS</h2>
45                <ul>
46                        <li>QGIS is a free, open-source GIS program licensed under the GNU General Public License. It runs on Linux,
47                        Unix, Mac OSX, Windows, and Android, and supports numerous vector, raster, and database formats and functionalities.
48                        The program can be downloaded at: <a href="http://www.qgis.org/en/site/" target="_blank">http://www.qgis.org/en/site/</a>.
49                        <br/><br/></li>
50
51                        <li>After installation, two main GIS programs will be available: QGIS Browser and QGIS Desktop. QGIS Browser is a GIS
52                        file explorer (similar to Windows Explorer, but only displaying GIS-related files). QGIS Desktop is the program
53                        where data are displayed, symbolized, and analyzed.<br/><br/></li>
54
55                        <li>In QGIS Desktop, the "Manage Layers" toolbar contains an "Add Vector Layer" button. Using that interface,
56                        navigate to the folder containing the .json and open the file. QGIS Desktop can open the .json directly,
57                        with no preliminary transformation being necessary. The .json can then be transformed to a different GIS
58                        file type (including shapefile) by right-clicking the layer name, and using the "Save vector layer as" command.
59                        <br/><br/></li>
60                </ul>
61
62                <h2>Important Note About Downloaded NJSHAD GIS Data</h2>
63                <ul>
64                        <li>The boundaries of all the GIS layers that are displayed and downloaded from NJSHAD represent slightly generalized
65                        versions of the actual geographic areas. Using simplified polygons reduces overall file sizes, which helps keep
66                        the NJSHAD web-mapping service operating smoothly and responsively. These generalized geographies are perfectly
67                        suited to viewing data distributions at the map scales that are available in the online NJSHAD maps.<br/><br/></li>
68
69                        <li>However, downloaded NJSHAD GIS boundaries are generalized, and do vary slightly from official US Census GIS data,
70                        for example (only on the order of several feet, in most cases). Hence, if more precise GIS spatial analysis and
71                        presentation is required, fully detailed GIS files will need to be found from an alternative source.<br/><br/></li>
72                </ul>
73        </CONTENT>
74</HTML_CONTENT>
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