What's Your Vector?
NASA Worldview vector layers bring a wealth of additional information about thermal anomalies, dams, nuclear plants, and more.
Josh Blumenfeld, NASA EOSDIS Science Writer
If a wildfire starts in the woods and no one is around to see it, how do you know when it started? Thanks to vector layers in the NASA Worldview data visualization application, the time an active fire or other thermal anomaly was first detected by an orbiting sensor – along with the approximate latitude and longitude of the anomaly, the fire radiative power, the brightness temperature, and much more – is only a mouse click away.
The release of Worldview version 3.8.2 expands existing vector capabilities to include fire and thermal anomalies layers created from Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared and Imaging Radiometer Suite (VIIRS) sensor data. These vector layers join existing vector layers for dams, reservoirs, nuclear power plants, and settlements created from datasets available through NASA’s Socioeconomic Data and Applications Center (SEDAC). A total of 19 vector layers currently are available.
A vector layer is different from an image layer. Image layers represent locations through a grid of cells or pixels with associated color values that, when combined, form an image. Vector layers, on the other hand, identify locations using points, line segments, or polygons. More importantly, vector layers have attribute information that can be examined when a vector feature is clicked. For example, when a vector point is clicked in the Dams layer, a table of attributes appears, including the dam name, river, main use, and representative capacity.
Just because a vector layer is loaded into the Worldview Layer List doesn’t mean the vectors being displayed are active or clickable. If you see the blue pointer icon next to the vector layer in the Layer List on the left side of Worldview, you should be able to click on a colored vector dot to open a window with attribute information associated with that vector.
If you see a gray pointer with a red X over it, however, you are zoomed out too far and the vector layer is being rendered as an image. Simply zoom in until the red X changes to a blue pointer, indicating you can click on the vector dot to open the vector layer attribute information.
Adding vector layers to the Worldview Layer List is easy. You can access vector layers by clicking the orange “+ Add Layers” button at the bottom of the layer box on the left side of the main window (number 1 in the image at right). This opens the imagery layer category panel. Select the Featured tab along the top row of the Layer Picker (2), then select vector layers listed under Fires and Thermal Anomalies (Vectors) or Socioeconomic Data (Vectors) (3). You also can access vector layers by simply typing “vectors” into the search box.
Once you add a vector layer, colored dots appear on the Worldview map indicating the vectors you can select (remember, you might need to zoom in to make the pointer on the vector layer turn blue, indicating that the vector dots are clickable and not part of an image layer). Clicking on a vector brings up a box with the vector information.
While the latitude and longitude information provided in the dams, reservoirs, settlements, and nuclear power plant vectors is the exact location of the feature, the location information provided in fire and thermal anomalies vectors is an approximate location of the detected thermal anomaly. Each MODIS thermal anomaly represents the center of an approximately 1 square kilometer (1 km2) pixel flagged as containing one or more thermal anomalies (for VIIRS thermal anomalies, the location given for the thermal anomaly is the center of an approximately 375 square meter pixel).
Want to add NASA Worldview vector layers to your own client system? Since all NASA data are free and open, the code is yours to use. Check out NASA's Global Imagery Browse Services (GIBS) API for Developers: Vector API documentation and visit the gibs-web-examples GitHub repo to find some live examples.
Thanks to NASA Worldview vector layers, a wealth of information about specific wildfires, dams, reservoirs, and other features is only a click away. See for yourself, and start exploring all the new features of NASA Worldview.
Published November 19, 2020
Page Last Updated: Nov 19, 2020 at 9:13 AM EST