How to download free Landsat imagery with USGS Earth Explorer?
Downloading Landsat Imagery using Earth Explorer. Remote Sensing Analysis. ArcMap Environment. Download Landsat imagery to your computer as a preliminary step for analysis to extract. (now Landsat 8) launched in February, 2013.
The USGS Earth Explorer is a similar tool to the USGS Global Visualization Viewer (GloVis) in that users search catalogs of satellite and aerial imagery. The USGS Earth Explorer is the new and improved version.
The USGS Earth Explorer gives some extra capabilities:
- Downloading data over chronological timelines.
- Wide range of specifying search criteria.
- A long list of satellite and aerial imagery to choose.
Explore one of the largest databases of remote sensing data and create some of your own land cover classification.
User Interface
The USGS Earth Explorer interface uses Google Maps. You can zoom in and out with the mouse wheel as if you are in Google Maps. Google street view is also enabled, where you can drop a marker and get a real view of the location.
First, you’ll have to create an account with USGS. In the top-right corner, click the Register button. As it’s a pretty painless process, you’ll receive instructions to activate your account.
In order to download data from USGS Earth Explorer, here are the four steps you’ll need to follow:
- Set your search criteria
- Select your data to download
- Filter out your data
- Check your results and download
Step 1 Set your area of interest in the “Search Criteria” tab
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Users can double-click the browser to create regions of interest. The region of interest (ROI) is the geographic boundary that limits the search to acquire data.
Pro Tip: The easiest thing to do is just to zoom into your area of interest. If you want to download free Landsat imagery for Hawaii, zoom into that area. Now, select the Use Map button. Immediately after, zoom out a bit and you can see that you now have an area of interest in your map.
Alternatively, you can use one of these options to create a region of interest:
- Using an address to search
- Importing a shapefile (in a zip file) or KML
- Or you can just double-click the map to make your ROI
You can also set a timeline for aerial and satellite imagery downloads in USGS Earth Explorer. You no longer need to search through a long list of acquisitions to find the correct date. This is a powerful tool that narrows down your search and saves you time.
Step 2 Select your data to download in the “Data Sets” tab
The Datasets tab answers the important question: What satellite or aerial imagery are you looking for?. The USGS Earth Explorer remote sensing datasets are plentiful: aerial imagery, AVHRR, commercial imagery, digital elevation, Landsat, LiDAR, MODIS, Radar and more.
It depends on the date and time for which Landsat scene you can download. In the Landsat Archive group, the most recent Landsat imagery is L8 OLI/TIRS and L7 ETM+.
The differences between the collections are based on data quality and level of processing. USGS will be classifying images into tiers based on quality and processing level.
Now that we’ve identified our area of interest of Hawaii in step 1, you can select a checkbox in the Landsat Archive category. On-demand means that you will be notified by email where you can download surface reflectance products from a separate interface for processing and data delivery.
Step 3 Filter your data in the “Additional Criteria” tab
90% of people go into the “Additional Criteria” tab to easily filter out scenes with too much cloud cover. Now, you aren’t able to filter to obtain the perfect cloudless image everyone wants. But you can set the cloud level to less than 10%, and this is what most people want… unless you’re into meteorological studies.
Here’s a brief explanation what each set of criteria does:
- Set the Landsat scene identifiers which is a unique way for naming convention and includes WRS path and row within it
- Filter the temporal condition of the scene as a day/night acquisition or nadir/off-nadir
- Specific the quality of the scene with Level-1 (L1) data products being the best available processing level. The Processing Software Version is what was used to generate that L1 product.
For the average user, you won’t need to set a lot criteria. Other than cloud cover, you can move onto downloading your satellite imagery.
Step 4 Download free Landsat imagery in the “Results” tab
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Now that the date range, type of data and additional criteria are defined, the search results tab will populate with data sets that match your query.
In the “Results” tab , you select the specific data set you want to download. But it’s good to check the footprint for exactly where that scene is located. You can also preview the data, which can be good to see exactly where clouds are in the image.
Download the data by clicking the “Download” button. If you are going to performing analysis on the Landsat data, the Level 1 GeoTIFF data product is probably the one you’re after, which will be the largest file size.
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Let’s Recap:
The USGS Earth Explorer gives a quick and intuitive way to download free aerial and satellite imagery. This tool gives a wide range of options. You can define the time period, geographic extent and imagery type. Test it out for free downloads of remote sensing imagery and more.
Steps to Download USGS Earth Explorer Data:
- Set region of interest and time period
- Specify the type of data you want
- Filter out the data that you don’t want
- Search data sets and download.
A big part of the USGS Earth Explorer is the data available from the Landsat mission. We tell you exactly what are the spectral bands, spatial resolution and temporal information for its incredible +40 year history. Landsat Program: Satellite Imagery Data and Bands
What’s Next?
Well, you downloaded the satellite data for some reason, right? What can you do with satellite imagery once you have it?
Satellite data like Landsat is made up of several spectral bands. These bands have combined to create a true color composite or false color composite. We have a guide to do this just for you. How To Combine Spectral Bands with the ArcGIS Composite Bands Tool
Landsat 8 Data
Need to classify the imagery? You can use supervised, unsupervised and object-based image analysis. Don’t know the difference between them? No problem. Image Classification Techniques in Remote Sensing
If you want more satellite, this list of 15 free satellite imagery sources should quench your thirst.
On a side note, USGS Earth Explorer now warehouses Sentinel-2 data. This is really your best option for crisp 10-meter continous coverage of the planet.
When downloading Landsat 8 OLI/TIRS Land Surface Reflectance from the USGS earthexplorer service, the usual archive has the following files in it :
For some scenes (e.g. LC82270652013236LGN00) though, we get the following
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The data stored in the .tif files is very different. When the _MTL.txt file is present, we have band 3 values from 6000 to 10000 for a scene in the amazonian forest. But when the .xml file is present, the values range from 0 to about 1500 (also for an amazonian forest scene which should have similar histogram).
All of the Landsat 8 information I could find assumes we get the _MTL.txt file and I was unable to find any information about the other one. There doesn't seem to be any option in earthexplorer to control which type of data you want to download.
Does someone know how to convert between the two ?
1 Answer
The difference that you see arise from having a mix of 'surface reflectance' data, and 'uncorrected' / 'raw' data.
The scenes with a MTL.txt are 'uncorrected' while the ones with the xml files are 'surface reflectance'.
I am uncertain as to why you have a mix of the two data types, but something must have gone wrong in the ordering or the processing of data.
It should be noted that when downloading the 'surface reflectance' product, you are supposed to get the xml files. The scenes where you have a MTL file are not atmospherically corrected, and will at times be difficult to compare over time or between different path / rows.