This is a land cover change visualization and data download tool. Visualize change by making selections from the menu panel on the left. The following instructions serve as a brief guide to its operation.
In order: Chrome, Opera, Firefox
Base layers
Pressing the "Select Base Layer" button on the menu panel reveals a set of map base layers that provide context, including place names, roads, topography, and aerial imagery. One layer is visible at time and selected by activating the radio button corresponding to the desired layer. These layers are made visible by reducing the opacity of the overlying data layer using the vertical slider position at the upper left corner of the map.
Data layers
Pressing the "Select Data Layer" button on the menu panel reveals a set of map data layers describing attributes of land cover. One layer is visible at time and selected by activating the radio button corresponding to the desired layer. The opacity of these layers can be reduced to show underlying base layers using the vertical slider position at the upper left corner of the map. A question mark icon to the right of each layer can be clicked to load a page with metadata.
Download Tile
Pressing the "Select Download Tile" button on the menu panel reveals a set of vector overlays to help with selecting regions for download. Double click in the map display to select a tile for download, and click once on a selected tile to remove that tile from your download list. Once a tile is selected the region will become opacity, and the download button under "Select Download Tile" will display the number of tiles selected. Pressing the download button will open a download form where all that is needed is an email address and your choice of datatype(s). Note that while the feature callout option is active, time series plotting by left mouse click is disabled.
Zoom
You can zoom in and out by using the mouse wheel or zoom to a box size by pressing the shift key then clicking and dragging on the map.
Pan
You can pan around the map by holding left mouse click and dragging.
Time Series
You can view a time series plot of the data displayed on the map by left clicking on a location of interest. The time series is an annual interval. Hovering on a time series line will display data value and year at each observation. Note that while the feature callout option is active (described above), time series plotting is disabled. The first time that you plot a time series, you might be waking up the drives, which will delay drawing the plot, subsequent requests for plotting will be near-immediate.
The default data view is the most current year of data for biomass. At any time you can display the data legend by clicking on the legend icon at the bottom of the button group along the upper left side of the map - the legend toggles on and off with a left mouse click on the legend button. Time series plotting with left mouse click works with all views.
View Single Year
Pressing the "View Single Year" button activates a single map view of selected data (the default view). A horizontal slider allows you to change the data year displayed.
Compare Years | Flicker
Pressing the "Compare Years | Flicker" button activates a single map view of selected data that will flicker between two years of data for easy identification of change. Two horizontal sliders allows you to change the data years displayed. Press the "Start Flicker" button to begin flickering the data years, press it again to stop. At any you can change either year slider, which will automatically stop the flickering. You can also change data layer opacity as well as base and data type at any time - flickering will not stop. Change the flicker speed using the "Flicker Speed" slider - units are milliseconds.
Compare Years | Split
Pressing the "Compare Years | Split" button activates a side-by-side map view of selected data that shows the top slider year data on the left and the bottom slider year data on the right. The map zoom and pan are synced, as is the cursor - the main cursor is an arrow while the synced cursor is a red circle.
Compare Years | Swipe
Pressing the "Compare Years | Swipe" button activates a side-by-side map view of selected data that shows the top slider year data on the left and the bottom slider year data on the right. Left click and drag the map swipe handle side-to-side to alter the year overlays.
Select Base Layer
Select Data Layer
Select Download Tile
View Single Year
Compare Years | Flicker
Flicker Speed (ms): 300
Compare Years | Split
Compare Years | Swipe
Data is available as tiles defined by the USGS ARD grid. A list of these grid tiles can be seen under "Region Selected". Please select the desired datatype(s) and enter your email address to receive data. Requested data can be accessed through download links shortly after submitting the request. Data will be available for one week.
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