Tag Archives: GIS

QGIS 2.8.1 Released

Today the next stable version of QGIS was released. It is being called QGIS version 2.8 ‘Wien‘. Wien is German for ‘Vienna‘ which was the host city for the QGIS developer meetings in 2009 and 2014.

QGIS2.8_splash

QGIS 2.8 Splash Page

Recently a new version of QGIS has been released every four months. This rapid pace of development has its pros and cons. On the plus side, the software is rapidly growing and improving. On the con side it has made it difficult to maintain documentation. It has also been an issue for people working on large projects. They have had to deal with the software changing every four months.

QGIS 2.8 is a special release because it is the first in a series of long-term releases (LTR’s). The idea is that one release per year will be an LTR. This means that the LTR release will be supported and available for download for one year. This way people needing stability can use this until the next LTR is released a year from now.

Some of the highlights are:

  • Numerous bug fixes and stability improvements
  • QGIS Browser is more responsive
  • Ability to select the units in the Measure tool
  • Improvements to editing: better control of snapping and a new suite of Advanced Digitizing tools
  • Improvements to the Map Composer such as better control over coordinate graticules and map rotation.
  • Symbology improvements such as filling polygons with raster images, ability to have multiple styles per layer.

The detailed list of new features can be found here: http://www2.qgis.org/en/site/forusers/visualchangelog28/index.html

Visit the download page and take the new version for a spin. Remember you can install it on Windows, Mac and Linux!

 

Noise Pollution and Health in the Urban Environment: A Pilot Project

In October 2013, the Seattle Indian Health Board’s (SIHB’s) Urban Indian Health Institute (UIHI) completed a noise pollution pilot study. The goals of this project were: 1) to evaluate the feasibility of community data collection and analysis via a low cost GPS/GIS workflow, and 2) to offer recommendations on the feasibility and next steps for scalability to the larger Urban Indian Health Organization (UIHO) network. The collected data could additionally illustrate community health needs when merged with health or other contextual data for analysis, but these analyses were not the primary focus of this pilot. We chose to look at noise pollution because it is an environmental health concern that has been linked to a variety of health conditions in both occupational and community studies and it is easy to measure with portable devices.

For field data collection, we used an iPad Mini with the GISPro and Decibel 10th apps. For mapping and spatial analysis, we used the open source desktop GIS software QGIS (www.qgis.org). While GISPro is a paid iPad app, the other programs are free. Data collection participants were staff recruited from the SIHB’s administrative, clinical and UIHI departments. We selected participants from this pool because they are representative of the staff at UIHOs who likely have limited experience with data collection and GIS. UIHI project staff trained seven participants in the iPad workflow and data collection process. This workflow consisted of five steps: 1) collect noise data with Decibel 10th, 2) export noise data via email, 3) take a site picture, 4) collect GIS data with GISPro and 5) export that GIS data.

Select pictures of data collection sites, taken by study participants using an iPad Mini; Seattle, WA

Select pictures of data collection sites, taken by study participants using an iPad Mini; Seattle, WA

When the volunteer participants were finished with data collection, project staff compiled and analyzed the data using QGIS and Stata. Data were merged with socioeconomic indicators from the American Community Survey by zip code. Participating staff were asked for their feedback about their experience and the usability of the tools.

Average decibel reading at the 17 data collection sites and per capita income of zip codes, location of the Seattle Indian Health Board indicated by yellow star; Seattle, WA; October 2013

Average decibel reading at the 17 data collection sites and per capita income of zip codes, location of the Seattle Indian Health Board indicated by yellow star; Seattle, WA; October 2013

That feedback, combined with the experience of project staff, suggested that the GIS software tools were user-friendly and highly effective. Thus, they are likely to be attractive to organizations with limited technology budgets. However, some of the other resources necessary for this project (i.e. the GISPro mapping app, the iPad and general GIS software expertise) are expensive and may be limitations for many UIHOs. In the future, the UIHI would like to use these tools to better understand the health of the community, as well as assist UIHOs in conducting similar projects in their service area.

For more information about this project, view the project brief at http://www.uihi.org/wp-content/uploads/2014/08/GIS-Project-Brief_20140604.pdf.

The UIHI is a division of the SIHB and is one of 12 Indian Health Service tribal epidemiology centers (TECs). Unlike the other TECs that focus on geography-specific tribal populations, the UIHI is national in scope, focusing on American Indians and Alaska Natives (AI/ANs) living in urban areas. The UIHI supports the efforts of Urban Indian Health Organizations (UIHOs) nationally, as they serve the health and social support needs of their urban AI/AN communities.

The Center for Public Service Communications and the National Library of Medicine provided funding for the UIHI to complete this project.

Display and Share Your Maps Online via GIS Cloud  

The third step in the workflow (outlined in the Introduction) is to share your maps online via GIS Cloud.  This is an online mapping platform. You can sign up for a free account, upload your data, and share your maps with others. The maps will be dynamic, meaning you can do things like pan and zoom, turn layers on and off and identify features.

GIS Cloud Homepage

GIS Cloud Homepage

Pricing

Your free account comes with a Map Viewer and Map Editor and gives you 100Mb of space in your cloud account. If you require more space you can upgrade to Premium subscription which offers 1 Gb of space. Premium accounts cost $55/month.

Data Upload

GIS Cloud accepts all common GIS file formats and the data upload section is very intuitive. You can zip all your data and just upload the zip file and GIS Cloud will take care of the rest. You can even drag and drop files anywhere in the browser and they will upload to your account. Once uploaded it offers a nice range of options for symbolizing your data.

GIS Cloud Symbology Options

GIS Cloud Symbology Options

Map Editor

Here you have a variety of tools available including those for data editing, feature selection, basic analysis, table joins, geocoding addresses. It even has a database manager. You can create new layers in your cloud account and edit them here. With the analysis tools you can compute areas, measure proximity of one feature to another, buffer a layer by a certain distance, and create density maps.

GIS Cloud Map Editor Toolbars

GIS Cloud Map Editor Toolbars

Map Viewer

Here your data can be viewed against basemaps such as Google and OpenStreetMap. Your map can also be shared and published. There are several ways to share your maps. The two easiest methods are to provide the link to your map, or embed the dynamic map in a web page. Clicking the Share and Publish button opens the window below. Here you are provided the url to your map viewer and the javascript for embedding the map into a webpage. I would have embedded a dynamic map here,  however, WordPress does not allow bloggers to post JavaScript on WordPress.org blogs. You can also share your map with other GIS Cloud users by Publishing the map. Click on the image below to open up the ENHIP Schools in a GIS Cloud Map Viewer window.

GIS Cloud Map Viewer

GIS Cloud Map Viewer

Resources

Our Resources page has a GIS Cloud document that covers uploading data, styling data and sharing a map.

There are additional online mapping platforms such as CartoDB and MangoMaps. We found GIS Cloud to be the best combination of being intuitive yet powerful. However, all three options have free licensing levels. So you can try them yourself and decide which works best for you. These other options will be covered in future posts. Happy mapping!

Map and Analyze Field Data with QGIS

After community field data collection, the next step typically involves bringing the data into a desktop GIS. This is the middle step in the workflow outlined in the Introduction. Here the data can be viewed against basemaps such as Google or OpenStreetMap, and combined with other organizational data. This is where analyses can be conducted. Presentation quality maps can also be generated in this step.

The software we found to be the best fit is QGIS. This is an open source desktop GIS software. It has many strengths:

  • It can consume many kinds of data, including all the data that would come out of the field data collection apps.
  • It is both intuitive and robust.
  • It has a large suite of geoprocessing tools for analyzing data.
  • It will run on Windows, Mac, or Linux.
  • It is free to download and install.
  • It is well documented.
  • There is a large user community.
  • New functionality is being continuously added. New stable versions are being released every 4 months!

 QGIS Browser:

QGIS has two main applications: QGIS Browser and QGIS Desktop. Browser allows you to preview your GIS data. It is similar to Windows Explorer, or Mac Finder, but is designed to work with GIS data. It has a File Tree, a main Display Window, Database Connections and Display Tabs (See figure below). It allows you to view basic information about a GIS layer and preview both the spatial features and the attributes. Data can be dragged and dropped from QGIS Browser to QGIS Desktop.

QGIS Browser

QGIS Browser

QGIS Desktop:

Desktop is the program for conducting analyses and making maps. It comes with tools for editing and manipulating GIS data. The main interface is similar to well known proprietary GIS packages with a Table of Contents along the left side. This shows your data layers and the symbol applied to them. The majority of the space is taken up with the Map Window (See figure below). Buttons along the left side allow you to add data to a map. Buttons along the top allow you to pan and zoom into the map. There are additional editing and data analysis tools available from menus.

QGIS Desktop

QGIS Desktop

With QGIS Desktop you can perform analyses such as calculating distances to resources, characterizing communities with socioeconomic data from the U.S. Census (NOTE: you will need to obtain data from the U.S. Census to do this), or generate new data like density surfaces.  The sky is the limit.

QGIS Desktop also comes with a Print Composer (See figure below). This opens in a separate window and allows you to craft a publication quality map. Common map elements such as a title, legend, scale bar, north arrow, logos, and text can be added. The final map can be exported in a variety of common image formats such as: jpg, png or tif. Maps can also be exported as pdf’s. If you want to do additional design work in a program like InkScape or Adobe Illustrator the maps can also be exported as svg files.

QGIS Print Composer

QGIS Print Composer

Resources:

While fairly intuitive, GIS work can still be rather complicated and full of jargon. There is a learning curve involved. To help with this we have resources that explain how to install QGIS and bring in data from the three recommended field data collection apps.

For more complete GIS training with QGIS there is the newly created FOSS4G Academy. This is a five course curriculum teaching GIS principles via QGIS. The material is available for free here: http://foss4geo.org/. The courses include:

  • GST 101 – Introduction to Geospatial Technology
  • GST 102 – Spatial Analysis
  • GST 103 – Data Acquisition and Management
  • GST 104 – Cartography
  • GST 105 – Remote Sensing

QGIS also comes with thorough documentation.

Download it today and try it out!

FOSS4G Academy Launched

For the first time there is a complete GIS curriculum based on free and open source (FOSS4G) software! Better yet the material are freely available to everyone. The curriculum consists of five courses:

  • GST 101 – Introduction to Geospatial Technology
  • GST 102 – Spatial Analysis
  • GST 103 – Data Acquisition and Management
  • GST 104 – Cartography
  • GST 105 – Remote Sensing
Examples of FOSS4G Academy QGIS Labs

Examples of FOSS4G Academy QGIS Labs

The courses were developed via the National Information Security and Geospatial Technologies Consortium (NISGTC), under the leadership of Phil Davis (Del Mar College). Kurt Menke (Bird’s Eye View), and Dr. Richard Smith (Texas A & M – Corpus Christi), authored the material which includes: theory, lecture, labs, data and task oriented video tutorials for each lab exercise.

The courses are aligned with the Department of Labors Geospatial Technology Competency Model (GTCM). The GTCM  was published in 2010 and will be revised in 2015. It describes the complete set of knowledge, skills, and abilities required by GIS professionals. It is designed around a hierarchical tiered model of knowledge and promotes use of open source technology.

GTCM

Geospatial Technology Competency Model

QGIS is the featured software for all courses. When appropriate other FOSS software’s are also included such as GRASS and InkScape.

The vast majority of US based colleges and universities use a single vendor’s proprietary GIS software, making this series of courses very unique. In fact it is the first national attempt at a completely open source GIS curriculum. By their very nature of open source software, there is no marketing engine promoting them. This has slowed the adoption and overall use of open source GIS. One hope is that this material will entice people to learn about the same low cost mapping workflows that the Community Health Maps program is promoting.

The targeted audience is broad and includes:

  • Secondary school educators and students
  • Two and four year college educators and students
  • Students in need of GIS skills
  • Workers seeking to broaden technology skills
  • Anyone desiring QGIS and open source knowledge and skills

The courses are available online at the FOSS4G Academy. Over 2,500 students have already enrolled for these courses demonstrating how in demand these materials are. Visit the FOSS4G Academy now and explore the material!

FOSS4G Academy

FOSS4G Academy

 

How Accurate is the GPS on my Smartphone? (Part 1)

Historically field data collection was a daunting task reserved for geographic information specialists (GIS) professionals, and the technical savvy crowd. This was largely due to the learning curve involved in operating mapping grade Global Positioning System (GPS) receivers. However, smart phones and tablets have changed that. They offer an amazing array of functionality in a portable, intuitive and ever more familiar interface. Think about all the technology packaged into one of these little devices:

  • GPS
  • Camera
  • Network connection (3G, 4G, WiFi…)
  • Email
  • Internet
  • Apps

They’re actually better than the Tricorders we used to see on StarTrek!  They have a slimmer profile, probably weigh a lot less, have touch screens, bigger displays and can be used with thousands of available apps.

iPhone vs.Tricorder

iPhone vs. Tricorder

One big question when considering smart phones or tablets for field data collection is, “How accurate are they?” A related question that must be answered is, “What kind of accuracy will meet the needs of my project?” You need to answer both of these questions to determine whether or not this technology will work for you. Usually survey grade GPS accuracies (sub meter or sub centimeter) aren’t necessary for public health mapping. Getting within 10 meters is more than adequate to map facility locations, patient addresses, potential sources of disease or wellness.

 How Does GPS Work?

The Global Positioning System (GPS) is a U.S. Department of Defense (DOD) system. It utilizes a constellation of 24 satellites orbiting the earth at an altitude of 12,000 miles. GPS devices compute your position by determining the distance between the GPS receiver and a minimum of 4 GPS satellites. The satellites transmit radio signals to the GPS receivers, allowing the calculations to occur. Initially GPS was established as a military guidance system, and I doubt anyone foresaw the popular use it has today.

The iPhone has been equipped with an onboard GPS since the iPhone 3, and Android phones became GPS enabled at about the same time. Typically people use GPS to find restaurants and street directions. However, there’s no reason these same devices can’t be used for public health data collection!

More About Smart Phone Locational Services 

Smart phones in fact use more than GPS to locate you. They employ a hybrid locational system combining three separate technologies:

  1. Assisted GPS (A-GPS)
  2. WiFi positioning
  3. Cellular network positioning.

These three technologies are used in combination as they are available. A-GPS is the most accurate of the three, and cellular positioning the least accurate. The figure below shows an example of the accuracy of each of these locational services.

Accuracy of iPhone Locations

Zandbergen, P. A. (2009). Accuracy of iphone locations: A comparison of a) assisted gps, b) wifi and c) cellular positioning. Transactions in GIS, 13, 5–25.

GPS Accuracy

There are a number of factors that affect accuracy no matter what GPS receiver is being used. The GPS radio signals encounter differing conditions while travelling through the atmosphere, causing signal delays, and therefore affecting accuracy. The geometry of the satellites being used will also vary. The GPS will have a wider array of satellites to choose from if you’re out in the middle of a big field, versus being on 6th Avenue in Manhattan. You will get better positions if the satellites you’re locked onto aren’t clustered in one part of the sky. Therefore the more sky view you have, the more accurate your GPS will be. In addition to blocking your view of the sky, urban canyons can also cause multipath effects, where the GPS signal bounces off of buildings or other objects reducing accuracy.

In part 2, I’ll discuss each of the three pieces of the hybrid locational system individually, and discuss exactly what kind of accuracy you can expect to achieve.