The primary benefit of Earth OnDemand is the ability to quickly and easily search across multiple catalogs of imagery data.
Search in Earth OnDemand is designed to enable iterative refinement. At a high level, the process for searching is:
- Specify Area of Interest
- Filter Results
- Select a image footprint
- Select a result
Step 0: Navigate to the Earth OnDemand Website
Step 1: Specify Area of Interest
All searches in Earth OnDemand start with specification of an Area of Interest.
- Click on the green "Draw Bounding Box to Search" button at the top left of the page.
- Draw a bounding box on the map around the area you are interested in searching across.
At this point you see green boxes pop up under your search. These are the footprints for the dataset you have selected. By default, Landsat 8 is selected so these are the footprints for the Landsat 8 scenes. Depending on the size of your Area of Interest, you may see one or multiple scenes. If you zoomed in and selected an AOI that is smaller than the image footprint, your whole screen may appear green like this:
Zoomed In Zoomed Out
This is expected - if you zoom out, you will see the footprint more clearly.
Choose your own adventure
At this point, you have three options. If you wish to refine your search further, you can continue to Step 2. If you wish to change the Dataset, jump to Step 3. If you want to view all the available imagery for the currently selected dataset (likely Landsat 8), continue to Step 4.
Note on image footprints
Different satellite missions have different purposes. Many of the public data sets such as Landsat, Sentinel, MODIS, and NAIP have a regular collection pattern. These platforms are typically focused on a general mapping mission across the entire globe. Other platforms, including many of the high resolution sensors, are tasked. These images do not collect all areas in a regular pattern. This also is the case with private data. If the data you are searching is not collected on a regular pattern, each image will appear with its own footprint on the map. If this becomes visually overwhelming, try filtering a more narrow date range or a smaller area of interest.
Step 2: Filter your results
Frequently, users wish to filter the results they receive by date and cloud cover.
- Select a start date for your search
- Select an end date for your search
Additionally, it is useful to filter out images with too many clouds.
- Adjust the setting to the maximum acceptable amount of cloud cover allowable in your search.
The cloud cover filter is based on the total cloud cover percentage provided in the metadata along with the image data. The percentage is based on the total area of the image scene - not the subset of the area in your AOI. If your AOI is smaller than the image footprint, you may wish to preview the images with higher cloud cover to see if the area you are analyzing has cloud cover.
Step 3: Select your Dataset
EarthAI provides access to numerous catalogs of data. By choosing from the different datasets, you can compare the coverage of the different data providers. Their coverage varies in both spatial extent and temporal density so be sure to look at the result histogram to see how much data is available over time.
For more information on the various datasets offered in Earth OnDemand, see the Overview of Datasets.
Step 4: Select a footprint
- The right panel contains previews of all the images that satisfy your search criteria. As you hover over these scene results, the corresponding grid footprint will be highlighted. Likewise, as you hover over grid footprints, the related scene result will be highlighted in the right panel. Click on a grid footprint on the map that you wish to analyze.
- Clicking on a grid footprint filters the scene results to that footprint. You can deselect the grid cell by clicking on the cell again or clicking the "Reset Grid" button in the scene results header section. To view an image, click on the preview in the right panel. Earth OnDemand will generate a RGB image and overlay this image on the map. This make take a moment as the computation is done on-demand.
Step 5: Iterate
You can continue to refine your search parameters in the left panel and inspect results in the right panel.