What is georeferencing?
According to the U.S. Geological Survey (USGS), “georeferencing means that the internal coordinate system of a digital map or aerial photo can be related to a ground system of geographic coordinates. A georeferenced digital map or image has been tied to a known Earth coordinate system, so users can determine where every point on the map or aerial photo is located on the Earth's surface.” (source)
In the world of mySidewalk, it means that you can take your data and assign it to a geographical boundary that mySidewalk maintains. This will allow you to use a known and easy to find geography when creating visualizations.
When should I assign a mySidewalk geography?
First and foremost, if you don’t know how to assign a geography any other way, then use the mySidewalk georeference tool. This will help you to upload data without directing you to a third party tool or gathering latitude/longitude coordinates that don’t really relate to the visualization you are trying to make.
Another great time to assign a mySidewalk geography is when you know the boundaries line up. There is no need to create a shapefile if you already have a CSV that references zip codes, cities or states (or any of the 16 feature classes we maintain) that are already mapped in mySidewalk. If the boundaries already match up, might as well use ours!
Pro Tip: think about the other metadata you want to include when uploading (like time) and organize your data accordingly. Learn how to get the most out of your data in mySidewalk.
When to NOT use a mySidewalk geography
Do not use a mySidewalk geography if it doesn’t represent the spatial boundary you want to reference. A park or school district boundary might not be represented in the mySidewalk geographies, so go ahead and make your own custom geography in that instance! (More on custom geographies here.)
What can I do once I have assigned a mySidewalk geography?
Once you have uploaded data (assigned to a mySidewalk geography or not), you now have a Layer. You can use your Layers in any visualization by choosing “Your Data”. You can also change the name of your layer or add tags in the Layers library.
Learn more using these links:
The first step of any data upload is to clean the data and ensure that it is ready for uploading to mySidewalk. (read more here).
First, we can remove all of the rows that we do not want to upload
Next, we need to make sure the first column is a 'label' column as it will not upload as data values, only labels.
When using a Single Feature - this should be a date/time reference.
When using Multiple Features - this should be a boundary.
Finally, we need to ensure that there is only one header column row (access a sample file in the cleaned format here)
Save the cleaned file as a .csv
1. Navigate to Layers and Add a Layer
Access the Layer library from the home page or the menu bar and then click Add Layer
2. Choose Upload and Georeference
Select “Upload and Georeference”.
Drag or choose a CSV file to upload.
3. When you only have one feature (Single Feature)
The Single Feature option allows you to assign all of the data in your file to one MySidewalk maintained geography. This can be any of the feature classes we support (e.g. state, county, place, zip code). Census tract and census block group are excluded.
Single Feature is very valuable when you can incorporate a time element to it. Your times should be the row headers and your indicator names (variables) should be the column headers.
Pro Tip: if you aren’t sure what to choose, assigning to your default geography is an easy choice that allows the data to be uploaded and used fairly easily by the majority of components.
4. When you have Multiple Features
The Multiple Features option allows you to assign a different geography to each row in the uploaded table. Every row must be assigned and duplicate geographies are not allowed (if you put the same zip code in two rows, only one row of data will load).
5. Manage and Use your layer
A successful upload will result in a layer being created and move you to the layer management page. On this page, you can update the name of your file, add tags, add a description and change the label of your file. It will also reveal if you have uploaded time in a way the system can recognize (this example does not have time included).
Pro Tip: choose a field to assign as the label - geography often makes the most sense
From here, you can click “New Report” to start building visualizations or choose Reports from the menu and choose an existing report. The Layer you built will be accessible from components if you choose “Your Data”.