At the Esri UK user conference I did a hands-on training session which showed attendees how to create a map journal based story map describing the effect of wind turbines on the landscape of the Lake District. Attendees were able to create a story map in the space of 30 minutes – the finished story map can be found here:
The story map is based on the map journal template and shows some of the things which can be included within it, such as text, video, photographs, links to other websites and, of course, ArcGIS Online web maps and 3D Scenes.
The visibility analysis was performed using ArcGIS Online – no desktop GIS software was used at all to perform the study, but due to time constraints it was not possible for attendees to create this dataset within the session.
So this article will show you how to create this missing piece of information which is an important part of the story map.
To perform the analysis you will need to get access to an ArcGIS Online Organisational Account.
It is possible that you already have access to one so it is worth checking with your GIS co-ordinator. If you don’t then you can create your own 60 day trial account from this link. https://www.arcgis.com/home/signin.html
Follow the instructions; add your details and you will be off and running very quickly.
The links at the end of the article provide some good resources for activating your trial subscription.
The visibility analysis used a single point layer which represented the locations of operational wind turbines from 2011.
1: Open up a browser and go to sharegeo.ac.uk
2: Type “wind” into the search box and download the “Windfarms in Great Britain – 2011” dataset.
3: Zip up the operational windfarms shapefile. ArcGIS Online will then be able to read the zipped shapefile as a single entity and display it within a web map.
Now you will add the windfarms into a web map which will be used to perform the spatial analysis.
To add the shapefile into the web map you should:
4: Create a new web map
6: You may wish to change the symbology of the layer from the default brown colour to some other colour, such as red.
Now that you have your organisational account and your source dataset you can start to perform some spatial analysis using ArcGIS Online.
Let’s do some spatial analysis in “The Cloud” using ArcGIS Online
Now you can perform the visibility analysis using the criteria which has been defined for you. Let’s make some assumptions about the wind turbines and the height of the observer… let us assume the turbines are 80 meters high and that the height of the observer is 1.5 meters. We will also assume that the maximum viewing distance is 30 km. Your analysis will be based around the nearest 15 points to the Lake District boundary.
1: Click on the drop down arrow to the right of your windfarm layer and choose Perform Analysis
2: Then choose Find Locations > Create Viewshed.
3: Fill in the variables in the Viewshed dialog:
- We will say that all the turbines are 80m – this is a generalisation
- We will calculate the viewshed for objects 1.5m above the surface to mimic the average person’s eye-level
- We will set the max distance to the maximum (30km)
This visibility analysis will cost 0.017 of a credit. A bargain!
5: Press the RUN ANALYSIS button to perform the visibility analysis.
It will take a few moments for the analysis to be performed. The resulting layer will be created using the name you specified in the designated location. The resulting visibility layer will be added to the web map:
6: The final thing you need to do is save the web map! This means that any content you have in your web map will be available when the web map is referenced within the story map.
So, in this short blog entry you have seen how easy it is to perform some advanced spatial analysis which is normally the preserve of desktop GIS. The beauty of performing this analysis in “The Cloud” using ArcGIS Online means it is so easy to share your results to other people or organisations using intuitive and accessible client applications such as a story map.