Find and download an image

To find a Landsat image of Singapore, you'll use the GloVis app to explore the entire database of free Landsat imagery. You want a relatively recent image with minimal cloud cover. To download the image, you'll create a free account for the USGS Earth Resources Observation and Science (EROS) Center, which will allow you to download as much Landsat data as you want.

Landsat imagery can be large. The file you'll download has a size of approximately 900 MB. Ensure that you have enough disk space on your computer, and enough time to wait for the download, before proceeding.

Create an account

To download Landsat data, you need a USGS EROS account. The account is free, but it does require you to give demographic survey data and contact information.

Note:

If you already have a USGS EROS account, skip to the next section.

  1. Go to the EROS Registration System.
  2. Follow the onscreen instructions to proceed through the registration process.

    Once you complete your registration, a message is sent to your email address to confirm your registration.

  3. Click the link in the email to activate your account.

Locate Singapore

Next, you'll open GloVis and navigate to Singapore.

  1. Open the GloVis home page.

    This page explains some of the new features you can experience.

  2. Click Launch GloVis to open GloVis.

    Launch GloVis button

    Note:

    The GloVis site is frequently updated and may look different than the example images.

  3. If necessary, close the Would you like to take a tour window.

    The viewer opens to the default location in the center of the United States. The Interface Controls pane includes parameters to search for Landsat imagery.

    GloVis app

    First, you'll sign in.

  4. On the black toolbar at the top of the map, click Login.

    Login button

  5. In the EROS Registration System screen, enter your user name and password and click Sign In.

    Next, you'll locate your area of interest.

  6. On the toolbar above the map, click the Jump To button.

    Jump To button

  7. In the Jump To Location/Scene window, click Lat/Lng.

    Lat/Lng in the Jump to options

    You'll enter the coordinates for the center of Singapore.

  8. For Latitude, type 1.36. For Longitude, type 103.82.

    Latitude and Longitude parameters

  9. Click Jump to Location.

    The map extent centers on the city-state of Singapore.

    Map extent jumps to Singapore

    Most of the island is heavily urbanized, with a few open green areas on the western and central parts of the island. Although the viewer has a scale bar in the lower corner, at this extent, it's difficult to discern Singapore's size relative to other geographic features.

  10. Click the Zoom out button two or three times.

    Zoom out button

    You can now see the size of Singapore relative to the surrounding countries, like Malaysia and Indonesia.

    Singapore to other countries in Southeast Asia

  11. Use the Zoom in button six or seven times to zoom in back to Singapore.

    Zoom in button

    You can now see the island of Singapore in detail.

    Zoomed in to Singapore

    A country the size of a single city presents unique challenges for land use and urban development. Although Singapore has expanded its area by reclaiming land from the sea, its confines remain generally fixed, necessitating stringent planning. But proper planning requires quality data.

Find an image

A real urban planning project would use a variety of data types from many sources. The single image you'll download from the Landsat imagery database will serve as a starting point, providing a high-quality look at the entire city.

Landsat imagery is multispectral, meaning that a single image is in fact a collection of several image layers, each acquired at a particular wavelength band. The layers can be displayed in various combinations to emphasize features such as vegetation, coastlines, or man-made structures. The Landsat image will be a good reference to which you can add more specialized data.

To search for your image, you'll first select the specific type of imagery you are interested in.

  1. In the Interface Controls pane, next to Selected Data Set(s), click the Click to add a data set button.

    Click to add a data set button

    The Add Data Set window appears. GloVis contains many imagery datasets, each one produced by a different satellite or aerial photography program. For instance, it includes the output of several United States Landsat missions and European Sentinel-2 satellites, all covering the entire earth.

    Note:

    You can click the information button to learn more about each dataset.

    Information button

    You're interested in finding a Landsat 8 or 9 image.

  2. Scroll down the list of datasets and turn on Landsat 8-9 OLI/TIRS C2 L1.

    Landsat 8-9 OLI/TIRS C2 L1 turned on

  3. Click Add Selected Data Sets.

    Add Selected Data Sets button

    After a few moments, the Landsat 8-9 layer appears in the map.

    Landsat layer on the map

    Note:

    The image that appears on your map is the most recently captured Landsat 8-9 image and will probably differ from the example image.

    The Landsat 8-9 layer also appears listed in the Selected Data Set(s) section.

    Selected Data Set(s) section

    In the Selected Data Set(s) pane, it mentions that there are over 300 scenes (or Landsat 8-9 images) matching your criteria.

    Note:

    Because new images are added daily to the Landsat 8-9 dataset, your search may have returned more images.

    Next, you'll limit your search to a specific date range. You want an image captured in the last few years, so you'll define the range as 2018 to the present date.

  4. In the Interface Controls pane, next to Common Metadata Filters, click the Click to add a metadata filter button.

    Click to add a metadata filter button

    The Add Filter window appears.

  5. In the Add Filter window, for Filter Type, choose Acquisition Date. For Acquisition Date Range, set the range from 01/01/2018 to today’s date.

    Add Filter window

  6. Click Add Filter.

    The extent shown in a satellite image can be partially or almost completely covered by clouds, based on the weather conditions at the time of capture. This is particularly true in a location like Singapore, where the climate is equatorial, which means it is hot, humid, and rainy throughout much of the year. You'll limit your search to images with a low percentage of cloud cover: clouds should not be present on more than 15 percent of the image.

  7. In the Add Filter window, for Filter Type, choose Cloud Cover. For Cloud Cover, set the range from 0 to 15.

    Cloud Cover filter

  8. Click Add Filter. Close the Add Filter window.

    The filter is applied. The Selected Data Set(s) section updates. (The image displayed on the map may also update.) There is now a much smaller number of scenes matching the criteria you specified.

    Note:

    Because new images are added daily to the Landsat 8-9 dataset, the number you see might differ from the number displayed in the example image.

    Scenes identified in the Choose Your Data Set(s) section

    Next, you'll browse through the images to choose the one that will best work for your purpose. To browse the scenes selected more easily, you'll display the timeline pane.

  9. In the Interface Controls pane, click the Show Timeline button.

    Show Timeline button

    The Result Timeline pane shows how many scenes were selected for each year. The precise date of the scene currently displayed on the map appears at the top of the pane.

    Result Timeline pane

  10. In the Scene Navigator window, click Previous.

    Previous button on the timeline toolbar

    The next most recent scene appears on the map.

  11. Use the Previous and Next buttons to explore the available images.

    As you move through the list, the current year appears highlighted in red in the timeline.

    Year 2020 highlighted in the timeline

    Many images still contain some cloud cover.

  12. Move through the list until you reach the image captured on 2018-05-24.

    This image is of excellent quality and contains almost no clouds.

    2018 image of Singapore with no cloud cover

    You determine that the image from 2018 is the best one for you to download.

    Note:

    It's possible that a new image has been added that shows a more recent image of Singapore with low cloud cover. You may choose an appropriate, more recent image if one is available.

Download an image

Now that you've chosen an image for your development project, you'll download it.

  1. On the Scene Navigator window, click Download.

    Download button

    There are various options listed to download the image. You'll choose Landsat Collection 2 Level-1 Product Bundle, which is the most appropriate format for imagery analysis. It contains all 11 Landsat 8 multispectral bands and other associated files, allowing you to change how the image looks to emphasize different features on the ground. In this format, the imagery is georeferenced, so when added to a GIS application such as ArcGIS Pro, it will automatically appear in the correct location on the map.

  2. For Landsat Collection 2 Level-1 Product Bundle, click the Request Download button.

    Request Download button

    The file is downloaded.

    Note:

    The download may take a few minutes depending on your computer and internet connection.

You've used the GloVis app to search the large database of Landsat multispectral satellite imagery. You also located and downloaded an image that will be useful raw data for your planning project in Singapore.

Note:

In this tutorial, you reviewed Landsat imagery from GloVis, but there are many other satellites you can explore and use in GloVis and other services. Consider exploring other satellite imagery apps, such as LandsatLook and EarthExplorer. You can also explore the Copernicus Open Access Hub.

Next, you'll open the image in ArcGIS Pro and change its band combination to show Singapore more clearly.


Prepare the image

Previously, you downloaded an image of Singapore taken by a Landsat satellite. Next, you'll prepare the image for analytical use. First, you'll extract the image from the zipped file format it was downloaded as. Then, you'll add the image to a map in ArcGIS Pro and symbolize it by changing its band combination to better show Singapore's urban features.

Unzip the image

Raw Landsat images have large file sizes. The file size is large partly because you downloaded a zipped file that contains more than 10 images of the same area, each representing a different spectral band. These individual spectral band files can be combined to create a multispectral image. To view all this content, you must unzip the downloaded file. You'll also create a folder to store the data.

  1. Create a folder named Singapore Data in an easy-to-remember location on your computer, such as your Documents folder.
  2. Locate the downloaded file on your computer.
    Note:

    Most browsers download files to your computer's Downloads folder by default.

    Downloads folder

    The file is named by its identification code on the USGS website, which is a long string of letters and numbers. The file has the extension .tar, which is a type of compressed file. You'll need to unzip the content to view the images.

  3. Right-click the file and extract it to the Singapore Data folder.
    Note:

    The process to extract files varies depending on your file compression utility.

  4. Locate the extracted LC08_L1TP_125059_20180524_20200901_02_T1 folder in Singapore Data.

    Extracted folder

    Tip:

    It is possible that your file compression utility didn't create the LC08_L1TP_125059_20180524_20200901_02_T1 folder, and instead placed all the image files directly under the Singapore Data folder.

  5. Open the LC08_L1TP_125059_20180524_20200901_02_T1 folder and inspect its content.

    The folder contains a number of TIFF images along with a few other files.

    Extracted files

    Most of the images have the same name as the original file, completed with two characters, such as B1, B2, and B3. The B stands for band; each image shows a different spectral band of the same image. The Landsat 8 spectral bands will be discussed in more detail later in the tutorial.

  6. Double-click the image file that ends with B1 to open it in your computer's default image viewer.

    Band 1 image

    The image is mostly gray, with some visible clouds. Features such as landmasses and oceans are indistinct and difficult to distinguish. Images of a single spectral band tend to look like this, as they cover only a small range of light wavelength. To make an image that looks like what the human eye sees, multiple spectral bands are usually combined into a multispectral image.

  7. Close the image.

Open the image in ArcGIS Pro

To combine several individual bands and view them as a single multispectral image, you'll start a new project in ArcGIS Pro.

  1. Start ArcGIS Pro. If prompted, sign in using your licensed ArcGIS organizational account.
    Note:

    If you don't have access to ArcGIS Pro or an ArcGIS organizational account, see options for software access.

    When you open ArcGIS Pro, you're given the option to create a new project or open an existing one. If you've created a project before, you'll see a list of recent projects.

  2. Under New Project, click Map.

    Map under Blank Templates

    The Map template creates a project with a default basemap.

  3. In the Create a New Project window, change the project Name to Singapore Development.
    Tip:

    By default, the project is saved to the ArcGIS folder, located in your Documents folder. If you want to save the project elsewhere, browse to a different location.

  4. Click OK.

    The project opens. For now, it displays only the default basemap.

  5. On the ribbon, click the View tab. In the Windows group, click Catalog Pane.

    Catalog Pane in the Windows group on the View tab

    The Catalog pane appears. (It may have already been open.) It contains all the folders, files, and data associated with this project. You'll use this pane to establish a folder connection to the Singapore Data folder you created earlier.

  6. In the Catalog pane, click the arrow next to Folders to expand it.

    Expand button

    The default folder associated with the project is Singapore Development, a folder that was made when you created the project and that shares the project's name. The folder contains some empty geodatabases and toolboxes but no actual data.

  7. Right-click Folders and choose Add Folder Connection.

    Add Folder Connection option

  8. In the Add Folder Connection window, browse to and select the Singapore Data folder where you extracted your Landsat image. Click OK.

    In the Catalog pane, under Folders, the Singapore Data folder is now listed.

  9. Expand the Singapore Data and LC08_L1TP_125059_20180524_20200901_02_T1 folders.

    Image data folder

    Tip:

    If necessary, to view the file names in full, drag the side of the Catalog pane to widen it until the full file names are visible.

    The folder contains the 11 individual spectral bands (B1, B2, B3, etc), as well as several other files. The product metadata file (ending with MTL.txt) contains information on how to combine the spectral bands into a single multispectral image and how to configure them for optimal rendering.

  10. Right-click LC08_L1TP_125059_20180524_20200901_02_T1_MTL.txt and click Add To Current Map.

    Add To Current Map menu option

    Note:

    If a window appears asking to build pyramids or calculate statistics for the image, click Yes.

    The image is added to the map.

    MTL.txt file on the map

    The image appears colorful because several of its spectral bands are combined. The layer is also listed in the Contents pane.

  11. In the Contents pane, examine the rendering information provided under the Multispectral_LC08_L1TP_125059_20180524_20200901_02_T1_MTL layer.

    Image rendering information

    The Red, Green, and Blue bands (or bands number 4, 3, and 2) are currently displayed through the Red, Green, and Blue image display channels. This is the Natural Color band combination. Together, the Red, Green, and Blue bands make up the spectrum of light visible to the human eye. Combining these three bands approximates how the landscape would look to a person.

Change the band combination

The Natural Color band combination can be useful for some applications, but analysts often choose other band combinations based on the specific features they want to highlight. You'll now learn how to change the band combination.

  1. In the Contents pane, ensure that the Multispectral_LC08_L1TP_125059_20180524_20200901_02_T1_MTL layer is selected.

    Contents pane showing the selected layer

  2. On the ribbon, click the Raster Layer tab. In the Rendering group, click the Symbology button.

    Symbology button

    The Symbology pane appears.

  3. On the Symbology pane, review the content of the Primary Symbology section, which lists the bands used to display the image.

    Bands used to display the image

    Only three bands can be shown at a time through the Red, Green, and Blue image display channels. As you saw in the Contents pane, the Red, Green, and Blue bands are currently selected, forming the natural colors band combination. For urban development, a band combination that emphasizes features relevant to the city and contrasts them with vegetated areas may be more appropriate. The following table lists each band and what it shows best:

    NumberNameWhat this band shows best

    1

    Coastal Aerosol

    Shallow water, fine dust particles

    2

    Blue

    Deep water, atmosphere

    3

    Green

    Vegetation

    4

    Red

    Human-made objects, soil, vegetation

    5

    Near Infrared

    Shorelines, vegetation

    6

    Shortwave Infrared 1

    Cloud penetration, soil and vegetation moisture

    7

    Shortwave Infrared 2

    Improved cloud penetration, soil and vegetation moisture

    8

    Panchromatic

    Black and white imagery, sharper detail

    9

    Cirrus

    Cirrus clouds

    10

    Thermal Infrared 1

    Thermal mapping, estimated soil moisture

    11

    Thermal Infrared 2

    Improved thermal mapping, estimated soil moisture

    The Red band would emphasize the human-made objects of Singapore's urban environment, while the Near Infrared band would emphasize its coastlines and vegetation. The Shortwave Infrared 1 band would also be useful to highlight vegetation and minimize the appearance of the clouds in the image.

    You'll change the three bands displayed through the Red, Green, and Blue channels.

  4. In the Symbology pane, set the following parameters:
    • For Red, choose ShortWaveInfrared_1.
    • For Green, choose NearInfrared.
    • For Blue, choose Red.

    Band combination

    The image on the map changes automatically.

    Imagery file with new band combination

    The coastlines are much more defined, vegetation appears in bright green, urban areas appear as light brown clusters, and water bodies in black or dark blue.

    On the Contents pane, the band combination has also updated.

    Contents pane showing new band combination

    As a shortcut, you can also set this band combinations and several other common ones through the Raster Layer tab.

  5. On the ribbon, on the Raster Layer tab, in the Rendering group, click Band Combination and observe that Vegetation Analysis is selected.

    Vegetation Analysis band combination option

    This is the name of the new band combination you created. As its name indicates, this band combination is a good one to highlight vegetation. However, it also shows other features clearly, such as the built-up urban environment and water bodies. As a result, this rendering is quite versatile. Other band combinations like Natural Color are also available in that list.

  6. Try out several band combinations through the Band Combination drop-down list, and check in the Contents pane what bands they correspond to. Finish your exploration by choosing Vegetation Analysis.
  7. Close the Symbology pane.
  8. Zoom in to Singapore using the mouse wheel button.

    Final image

    This image gives a good overview of the whole island, with differences between urban and vegetated areas visible at a glance.

  9. On the Quick Access Toolbar, click the Save Project button.

    Save Project button on the Quick Access Toolbar

    The image is now ready to be examined visually, used as a background to display other data, or used in further imagery analysis workflows. While urban development projects require far more than only one image to plan for a city's future, this image provides a good starting point.

    Note:

    To learn more about imagery analysis, see the Learn ArcGIS tutorial Assess hail damage in cornfields with satellite imagery and other tutorials available in the Extracting Information from Imagery section of the Introduction to Imagery and Remote Sensing curriculum.

In this tutorial, you searched the large, 40-year database of imagery captured by Landsat satellites to find one showing the island of Singapore for a potential urban development project. After identifying the image, you downloaded it, opened it in ArcGIS Pro, and changed its band combination to better show the city.

Note:

An alternative to downloading imagery to your local computer, as you did in this tutorial, is to use an image service. This method allows you to view and, in many cases, analyze imagery that is hosted in the cloud, which can save time and disk space on your computer. Explore examples of Esri-hosted image services from the ArcGIS Living Atlas of the World imagery catalog.

To learn more about using a cloud-based image service to access imagery data, see the Learn ArcGIS tutorial Explore dynamic imagery of a volcano eruption.

You can find more tutorials in the tutorial gallery.