Spatial data related to voucher specimens are fundamental for research. Spatial data come in many formats, from textual descriptions of locations to latitude/longitude coordinates or Well-Known Text (WKT) representations of coordinate reference systems. Curators and managers of museum collections incorporate spatial data when cataloging new specimen records, and validation of such data is essential for ensuring and improving data quality and discovery. Below we share some workflows for viewing, validating, and cleaning locality data prior to integration into Arctos. Specifically, we present ways of cleaning Excel spreadsheets (e.g., when coordinate data are in variable formats), and how to use open-source GIS tools to map and validate locations.
- Excel or any spreadsheet program
- Quantum GIS (QGIS) – available here: https://download.qgis.org (if you’re not sure which version to download, try the Long Term Release for the most stable version. We use 3.4LTR for our examples)
Excel or any spreadsheet program; these steps work in Google Spreadsheets!
First we’ll start with filtering our long spreadsheet of specimen records to unique localities. This can be done with filtering on column values.
- First, make a copy of your sheet in Excel. (Right-click on the tab name and choose Move or Copy sheet. Choose Copy.) We will make our changes to the copy sheet. Rename it.
- Highlight the Locality field or simply the entire first row and click on Data–>Filter or on your Toolbar
- You will be able to select and delete redundant data. Delete fields that are not relevant or useful for Locality validation. Choose at least Site name, latitude and longitude in Degrees, Minutes or Decimal Minutes and Seconds, Datum, Higher Geography fields and Verbatim Locality.
Next we will convert the different geo-coordinate formats to decimal degrees (DD.DDDDD), which is the only format that maps geometry in GIS. Common formats for Latitude and Longitude (either from GPS units or topo quads) may be Degrees Minutes Seconds (DD MM SS.SS) or Decimal Minutes (DD MM.MMM).
- Use Data–>Text to Columns to separate out a single column of latitude into separate columns for degrees (DD), minutes (MM) and seconds (SS).
- Use this formula in an Excel field: =DD+((MM/60)+(SS.SS/3600)) where the DD, MM, SS refer to corresponding cells in Excel, eg, A2, B2, C2 for Degrees, Minutes and Seconds of Latitude and Longitude.
Quantum GIS [Coming Soon!]
We’ll assume that you have a fresh Installation of QGIS. We choose to install the Long Term Release or LTR version, currently at 3.4
- Note the Toolbars (Toggle Manage layers toolbar)
- Control which Panels are visible →right-click on the Tool bar region
- Find the Browser panel to navigate datasets on your local drive or services; Layers panel to control datasets in your Map View, draw order etc.
- Plugins to install–> Open plugin manager(top menu bar);we will use functions from these three plugins:
- Spreadsheet Layers
- OpenLayers Plugin or HCMGIS Plugin (newer one)
- LatLon Tools
Further Reading and Documentation – QGIS Users Guide