Data Challenges

Is the map giving you the information you need?

This is a very important question. Maps are data visualizations, and just like a graph, they can be good or bad. When we ask a map a question, like "where are all the Brownfields sites on our reservation?" we want to make sure that the answer we get is good quality and in a useful format. So how do you judge the quality of a map?

To begin with, it is important to understand that when you look at a mapping tool such as EJScreen or CEJST, you are looking at a composite that consists of a base map, a user interface, and a database. You can do some quick quality checks on each of these components. 

Base Map

All mapping tools provide you with one or more choices of base maps that act as the canvas upon which you layer your data. The base maps may provide you with quite different information because they may or may not include such things as reservation boundaries, municipal boundaries, federal lands, names of rivers, and so on. If information that is important to your work is missing from the base map you may have to either switch base maps, if that is an option, or add a data layer to your map. You may also be given a choice between satellite imagery, topographic map, street map, gray canvas, or other styles that are useful for different purposes. Note that base maps created from satellite imagery or topographic maps won't have boundaries represented on them and you will have to add a layer if you want to include things like reservation boundaries.

Base maps may be controlled by the company or organization that designs the mapping tools, or they may come from other sources:

• Google curates it's own base map, so when you use Google Earth, My Maps, or Earth Engine, you are using a tool from the same company that controls the base map. 

• ESRI, in contrast, provides you with base maps that are developed and curated by other companies and organizations. So, for example, when you use a tool based on ArcGIS you may be using base maps from Microsoft, National Geographic, USGS, etc. In the case of ESRI-based tools, you will need to think about the fact that when you switch base maps you will get different information and it will vary in quality. 

• CEJST is built on yet another platform, MapBox, and CEJST uses a base map from OpenStreetMap.  

Below is a comparison of base maps available in EnviroAtlas that differ in the way they represent reservations. The USGS National Map shows the Cherokee Nation as a  single point with a street address; the Microsoft Bing Street Map does show the reservation boundaries, but they are very faint and difficult to see; the OpenStreetMap base map in EnviroAtlas shows the reservation boundaries in Oklahoma very clearly. 

GIS specialists spend a lot of time thinking about base maps, but for our purposes we just need to be aware that different tools offer different base maps, and that base maps differ in the information they give you. 

To determine if the base map you are using is of good quality and fits your needs you can ask the following questions:

• What is the resolution of the imagery and data? 

• How often is imagery updated?

• Can you access imagery from different dates or zoom levels?

• How well geolocated are data points? 

• Are quality control checks in place?

• Is 3D or 360 imagery available?

• Can you import your own imagery layers (for example, drone imagery) or imagery provided in a library such as ESRI's Living Atlas?

Changing zoom level can give you different options when using some mapping platforms. This can be especially useful for virtual visits to a property. Note that the imagery date for the aerial 3D view is at the bottom of the page on the Google Map on the left and the date for the drone view is in the information box on the upper left side of the image on the right; the two imagery layers are obviously from different dates.

As you can see in the screenshots from Google Earth Pro below (using the time slider) there can be considerable variation in imagery depending upon the technology available at different time periods.

Although you can't choose the date of the imagery when you are using tools like EJScreen, you can use the time slider in Google Earth Pro to access imagery from specific dates. This can be very useful for determining past uses of a property.

Check the bottom of the map for dates and sources of imagery, keeping in mind that when you move to different locales or different zoom levels the imagery date may change.

User Interface

The mapping tool's user interface is created by an agency or organization to give you the tools and output reports that you need for your work. These user interfaces may be custom built, or they may be created using an app builder or API. The important thing to note is that the user interfaces are set up to help you get the information you need from the tool.

There are two broad types of mapping tools that you might encounter; the first is a map that provides you with a series of tools that you can use to construct your own queries, the second is a dashboard that provides you with a series of pre-set analyses and reports.

The screenshot on the left below is from EnviroAtlas, a mapping tool that allows you to access a large amount of information and analyze it using many of the tools typically used by GIS specialists working on ArcGIS online. In contrast, the screenshot on the right from the CMRA tool gives you pre-set analyses and downloadable reports. Note that EnviroAtlas emphasizes the map while CMRA emphasizes the reports and analyses.

A good quality user interface will make it easy for users to find the tools and controls that they need and will give a consistent, easy to understand experience. Since mapping tools vary a great deal in what they allow you to do, make sure that you choose a tool to fit your needs. For example, the EnviroAtlas Change Analysis Tool will let you run scenarios based on different climate projections, but EnviroAtlas will also allow you to identify watersheds, measure elevation profiles, visualize urban tree cover, and a whole host of different tools and data layers needed to create complex analyses. In contrast, although the Climate Mapping for Resilience and Adaptation will allow you to run climate projections and provide you with detailed reports on the various climate risk categories along with an estimation of the community's ability to adapt and recover from climate impacts, it does not give you any tools to run your own analyses. Your needs and your skill level will determine which approach you prefer.

Some questions to ask when judging the quality of a User Interface are:

• What tools are provided in the mapping platform, and how easy are they to use? 

• Can you import your own data into the mapping tool?

• Can you export data from the mapping tool?

• What reports or analyses are provided?

• Are you provided with instructions or supporting materials to help you learn how to use the tool and interpret the results?

• Can you print the map and does the mapping platform provide a good quality legend?

Databases

The data used by mapping platforms such as the EJScreen, EnviroMapper, CleanUps in My Community and EnviroAtlas all come from the same federal databases. These tools use data that are standardized nationwide such as ACRES or NPL Superfund. As a quality control measure make sure you are acquainted with the limitations of the data and whether it might be preferable to use a mapping tool that is produced at the state or local level that may use better quality data for your area.

A good quality mapping tool will provide you with documentation on the data they draw on and links to sources. For example, CleanUps In My Community has extensive documentation, as do EJScreen  and CEJST. EnviroAtlas goes one step further and provides peer reviewed papers and fact sheets for the data layers.

Some questions to ask when judging the quality of the data are:

• Is there a way to provide feedback to correct problems in the data?

• Can you export the map in different file formats (CSV, SHP, KML, geoTIFF, etc.) and how easy is it to export a file with the data you need?

• Does the mapping platform provide access to the data table for different layers?

• Is there documentation for the data sources and quality?