Turn Opendata into Geodata with GeoWE GISWEB, create your own layers and maps from online free resources.

Nowadays there are a lot of free datasets on the Internet, and many of them are not geographic data. However most of the data from opendata portals are referred to the territory,  assigned to a location such as a village, city, country, etc.

In this article, we will geolocalize a data source using a geographical layer, by joining common attributes from both datasets referred to the same location by a code or name.

In other words, we will add thematic data to a geographic layer to create richer layers, so it can be used in geographic analysis or thematic maps.
Image 1: Create thematic Layers, USA Divisions

For this purpose, we are going to use GeoWE, a powerful geographic information editor. We are going to make an example of attribute data managing, without a specific target, just to show data join tool potential, so that each data manager can use it according to their needs.

Objetive

This is an example of how you can create new geographic layers and maps from non-geolocalized alphanumeric online data, easily, using online free resources.

It is proposed as an example to add its Division value to each geometry of the States of USA, to be able to make a map similar to that in the image1.

Steps in this example:
  •     Find, select, and load geographic base layer
  •     Center view layer
  •     Find, select, and join thematic data to geometries
  •     Rename and Save new layer
  •     Apply style to attached data
  •     Print layer on a map
Find, select and load geographic base layer

Using google and searching "usa states geojson", we find http://eric.clst.org/Stuff/USGeoJSON
For this example, we will use this layer: USA States, 500K, GeoJSON

Open GeoWE and load layer

To start working, we need to access the GeoWE platform, either through its website http://www.geowe.org, or directly at the following URL: http://map.geowe.org.

To load data, follow this Steps:
Press: Menu --> Layers --> Vector --> Add layer --> Vector--> URL

Use this values in New layer form:

Layer name : USA_STATES
URL: http://eric.clst.org/wupl/Stuff/gz_2010_us_040_00_500k.json
Projection : GWS 84
Data format: GEOJSON

Next, push OK button:

 
Image 2: load geographic data from URL in GeoWE
Check layer attributes

Once layer is loaded, we can also review its attributes by pressing Layers --> i (Info). We can see metadata of the layer and its attributes, in this case, "STATE" and "NAME" could be used to do the data union, either by a name or by a code.

Image 3: Layer info

Center view layer

In order to get focus on the geographical area of ​​the map (Continental United States), we will use the Extensión tool, we center the map with the zoom that we want to use, then:

Press: Extension --> Current --> Add to map

Image 4 : BBOX to zoom map

A layer with the map extension (also called BBox) is added in GeoWE, so that it is not shown, we will go to:  Menu -> layers, and uncheck BBox layer.


IMAGE 5: Uncheck BBox Layer

Whenever we want to center the map, we just have to click on the BBox layer, in the layer manager.

Find, select, and join thematic data to geometries

We will use data from the United States census.gov datasets, selecting a table within its dataset, that contains informatión of state name and its division, SCPRC-EST2016-18+POP-RES.csv

Taking a look at the data, we can see that "," is the fields separator,  and that dataset contains "division", thematic data field we want to add, and "state" as the join field .

IMAGE 6: Csv data structure

Join data

Next step is to go to the layer information section of "USA_STATES" again and click "Join data from csv" --> URL

We used this values in data add Form:

Separator: "," (default value)
URL: http://www2.census.gov/programs-surveys/popest/datasets/2010-2016/national/detail/SCPRC-EST2016-18+POP-RES.csv
Next, push: Load File

Now we can choose join fields from two data sources, in this example the join fields have the same name, this is not necessary:

Bindable attribute = "STATE"
Layer attributes = "STATE"

Next, push OK button:

Image 7: Add Thematic information to layer
Check join

To check the operation we can query the layer attributes again with the Info tool

Rename and Save new layer 

Now that we've created a new layer, we can save it to our hard drive, or to our Github repository (if we have it), we will first rename layer, and then proceed to save it.

Rename layer

In Layer Info form, we can push Rename, set a new name and then push Apply.


 Image 8: rename layer

Export layer

We will use the layer administration form to download the layer, by using the cloud with an arrow icon (Export layer).

Image 9: Export layer

Apply style to attached data

Now we will use the GeoWE style tools to label the states with their name, and show each division in a different color.

Labeling

Pressing: Layer --> Style --> label attribute --> Check ("Enable attribute labeling")
We select  Lavel Attribute = Name
Font size = 8
Next, push the Apply button:

Image 10: Laveling Layer

Apply thematic style to layer

Pressing: Layer --> Style --> Color theming --> Check (enable Color theming)
We select Lavel Attribute = "DIVISION"
Next, push: Apply

Image 11: Aply thematic Style to Layer

Now we can check results

Image 12: Usa States by división

Print layer on a map

GeoWE allows us to print the map that we have created, so we will click on the printer icon in the upper right toolbox.

 
Image 13: Print Map

We have to select the layer that we want to print on the map, add it,(by clicking "Add Layer") and type a title (push "Apply" to apply changes). Finally, when we push "Print", GeoWE open the printer manager of your computer, you can print to pdf (you need extra software), send to printer, etc.


If you have completed this mini tutorial, congratulations!!!!
You have created your own geodata, and put it on a map, on web, using online free resources !!! 
 

Comentarios

Entradas populares