Monday, May 30, 2016

Open Source Cloud GIS System Setup with Amazon EC2 and Geoserver

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Follow these steps to set up the open source cloud based GIS mapping system.

1. Create an Amazon Web Services (AWS) account. You can find instructions for this step in the EC2 Getting Started Guide.

3. Create an Amazon EC2 instance. Instructions are also in the EC2 Getting Started Guide. When choosing an AMI make sure you choose a Windows server with IIS (and ASP.NET) already installed.

4. Connect to your Windows EC2 instance and install GeoServer. You can download GeoServer here. There are multiple setups available. Use the Windows installer. The instructions for the install are here.

5. Copy GIS data and configure map layers. The GeoServer user's manual will guide you through the steps of configuring GeoServer.

6. Start GeoServer on the EC2 instance server.

7. Seed the layers in GeoWebCache on the server. Instructions for this are here. Note that jpeg tiles are smaller than png and the default for base layers. Also png are better quality and will always be used for overlays because they can be transparent and overlays need to support transparency. Seed all layers for zoom levels 0 to 10 for EPSG:4326. If it is a base layer, seed it with jpeg files. If it is an overlay layer, seed it with png files.

Sunday, January 13, 2013

Popular GIS Books

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Books Pro Cons
It provides solid guide to how geospatial analysis work, particularly with respect to GIS. The book emphasizes conceptual workflows and with basic math which is helpful for creating own code and also getting an understanding of what's happening under the hood in contemporary GIS. It is better to have an update because lots of changes in GIS software over last five years.
This book is for typical GIS user aspiring to design good maps. It is illustrating GIS map software and throughout with map samples in color which is especially useful for those who has little prior training or experience in map making. This is acceptable book for beginners but very little information of advanced users. It hardly touches on advanced cartographic representations.
This book explains the computational geometry and algorithms concisely and very readable. It emphasis on describing algorithms and data structures theoretically. It presents pseudo code with lots of figures that is very easy to understand and follow.

It's also worth reading for all computer scientists and mathematicians who are working on geometry.

This is good text/reference book for graduate course.
Focused on geometric computation and algorithm, very complicated for beginners, who does not have prior computer programming knowledge.

The various algorithms and concepts often used in this book are triangulation, indexing, calculating intersection, shortest paths etc.
The book illustrates the most common cartographic deceptions, and provides some excellent color guides. If you want to learn how to make influential maps for a cause, this is the book!. The reader can learn what to look for and how to avoid the inadvertent or unintentional 'lies'. Worth the effort! Basically, the book as an introduction to the science of cartography and targeted for prospective cartographer or decision making authority.
The book details the use of freely available open source mapping software and tools such as MapServer, GDAL, OpenEV, and PostGIS to create web gis and web maps.

Mostly focused on UMN Mapserver for web mapping and building web gis.
Not much technical discussion on how GPS databases work, how to decode GIS information.
The book is fairly shallow. It will give you a couple of basic examples of how to use some pieces of software, but for anything more complicated, you have to look elsewhere.

Tuesday, January 8, 2013

Spatial Developer must keep in your shelf : Book Review

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One of my client’s requirements was to create and open source geospatial DBMS to hold utilities and city shape files. As looking through the internet, I found PostGIS is an open source software program that adds support for geographic objects to the PostgreSQL object-relational database.  As project reference, I choose PostGIS in Action, as project accomplished successfully I realized  my judgment was excellent.

PostGIS in Action is a very comprehensive introduction to PostGIS for developers of all levels of experience. Basically it is split into 3 parts:

Part 1- Nice and slow startup with PostGIS. You can skip this section if you have prior knowledge about any kinds of spatial databases and geometry data types.

Part 2- Put PostGIS in work. It contains technical details on proximity analysis, geocoding addresses, manipulating polygons and lines, and scaling and rotating geometries as well as efficient queries and how to tune your database and
selection of appropriate indexes and keys for your data.

Part 3- Use of PostGIS with other tools and frameworks. It describes manage raster datasets in PostGIS with PostGIS raster module, development of Web applications using PostGIS.

The Book will provide the much needed skills in building a spatial database, Application Server, Desktop GIS and Cartographic map renderer, Map tile server and Web map component using the following software: PostGIS/PostgreSQL, GeoServer, Apache/Tomcat, uDIG, Openjump, QGIS, GRASS GIS and Openlayers.

Thursday, July 19, 2012

Interactive Obesity and Rural Health Map

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An interactive maps shows the influences of landscapes in rural health using ExtJs,GeoExt,Openlayers,Geoserver,PHP,Jquery, JavaScript, and other opensource tools.
Check it out




Tuesday, June 5, 2012

Interactive West Nile virus incidence mapping using OpenGeo tools, Google APIs, & HTML5

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The Geographic Information Science Center of Excellence at South Dakota State University developed a web based West Nile virus (WNV) mapping application using Geosever, Openlayers, PostGIS,GeoWebCache, Jquery, Google visualization APIs, and, other open source technologies. This application allows users to pan, and zoom to visualize historical WNV patterns while using a slider bar to navigate through time. Users can click on counties to see -county level time-series graphs, case counts, and total population. The application also supports changing choropleth transparencies, choropleth classifications, and map backgrounds.

Methods:
A. OpenGeo tools:

i.     Open layers
ii.    Geoserver
iii.   WebGeoCache
iv.   PostGIS

B. Google APIs
i.       Google Maps API
ii.      Google Charting API
C.      HTML5

These are frequently refereed to as HTML5 technologies.
Javascript
HTML Canvas
WebGL
CSS3
Other CSS improvements such as flex boxes
Offline Storage
Geolocation
New events such as touch and orientation
Ajax
Websockets
Click here to visit the Application





Thursday, February 9, 2012

An Interactive Visualization using Geoserver & Openlayers

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From last couples of week, I have been involving to develop a interactive web interface for West Nile virus incidence dissemination across the conterminous US from 1999-2011.

The image on the right shows one of my accomplishment using
Geoserver,Openlayers,jQuery, PostgreGIS,and Google API. The project is about to launch online, then I will post a complete link of the project to let you guys play around it.

Click to visit: Web application


I am willing to help any one who is stuck with web maps/visualization and also seek constructive criticism on web stuffs.



Thursday, November 17, 2011

How to retrieve WMS GetFeatureInfo from Openlayers & Geoserver

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map.events.register('click', map, function (e) {
//alert(map.getExtent().toBBOX());
x1=parseInt(e.xy.x);
y1=parseInt(e.xy.y);
    var url = layerhost
      + "?REQUEST=GetFeatureInfo"
      + "&EXCEPTIONS=application/vnd.ogc.se_xml"
      + "&BBOX=" + map.getExtent().toBBOX()
      + "&X=" + x1
      + "&Y=" + y1
      + "&INFO_FORMAT=text/html"
      + "&QUERY_LAYERS=" + layername
      + "&LAYERS="+layername
      + "&FEATURE_COUNT=50"
      + "&SRS=EPSG:900913"
      + "&STYLES="
      + "&WIDTH=" + map.size.w
      + "&HEIGHT=" + map.size.h;
    window.open(url,
      "getfeatureinfo",
      "location=10,status=10,scrollbars=1,width=600,height=150"
    );
  });

I got  X and Y points due to floating point error while retrieving GetFeatureInfo . In order to prevent those errors I parse e.xy.x and e.xy.y values into integer, and it works for me.

Wednesday, May 25, 2011

Choropleth mapping techniques for Web2.0

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For my recent project, I have to display county wise time series data of disease pattern in web map for the conterminous United States for 20 years. In addition, I have to use Google maps as base layer and should overlay images on the top of it.  The concept sounds easy, and it was also similar with choropleth or thematic mapping. However, it should be in the Web 2.0.

I tried to figure out what are the possible ways to achieve this, I tried and few of them. Here I am going to share the pros and cons of these methods in a real quick and dirty style.

Choropleth with GFT
1) Google Fusion Tables

Pros:
Easy, No understanding of computer programming needed. Upload small or large data sets from spreadsheets or CSV files. Visualize your data on maps, timelines and charts. Pick who can access your data; hide parts of your data if needed. Merge data from multiple tables.

Cons:
Not much flexible and you can’t tweaks easily according to your needs. 

Choropleth with Cartographer.JS and Google API
2) Cartographer.js and Google API

Pros: It generates choropleth maps directly from database or other standard data handlers. Fast for small area mapping.

Cons:
Understanding of JavaScript is needed. It supports only US (County and State level data). I got performance is worst if we map entire 50 states. I recommend it to use to map few states only. Although cartographer.js's documentation claims browser friendly, it is horrible with IE, works so so with Firefox and chrome. 

 

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