The first question you typically ask yourself when you want to start using geospatial data is where to find it. There are different approaches to this, one is just to google it by combining the topic you are interested in with words such as GIS data or map data. Another approach is to use a metadata server. Metadata data servers typically allow you two different search approaches namely either search by predefined topics, here the most common topics are the ISO topic list or the EU INSPIRE themes. You can read more about these topics in the post Locating data by Topic. The other search mode allows you to combine different keywords and free text search in a more specific search.
Many organisations including RUC have such metadata servers. You can learn more about searching for geo-spatial data, including a list of the metadata servers I know of in the post “Searching for geospatial data”. Once you have located the data you are looking for you will typically be presented with a series of ways to access the data as seen below
Exactly which choices you are presenting with depends on the software running the metadata server and which ways of access are available for the data you have located. In relation to accessing the data you typically have two main options, either download the data or access it as a service. Both options often support different standard data formats.
If you wish to access the data as a service, i.e. let the data stay at the original location and access it online, the most common standards are WMS and WFS. WMS is typically used for ready symbolized data like digital versions of paper maps or images, while WFS is more suitable if you want to do your own symbolization or even do analysis. You can read more about the different standards for data services in the post “Data and service standards for geospatial data”
If you wish to download the data to your local computer there is a host of formats for this. The most common formats for downloading data to your computer are GML and GEOjson although others such as “shp” files and “geopackages” are also often seen. Again you can read more about the different standards in the post “Data and service standards for geospatial data”.
The choice of downloading the data vs. accessing it as a service is not trivial. The obvious advantages of downloading data are:
- You don’t have to be online
- The data won’t disappear
- It is typically faster in analysis
The advantages of accessing data as a service are:
- The dataset might be huge and not fit onto your computer or you might only need a limited part of the data.
- You will always be using the current updated version and especially administrative data is typically updated frequently.
- You don’t have to hassle with storing the data on your computer.
You can find a description of how to load data into a series of selected software systems in the post “loading geospatial data”