Retrieve historical imagery
First, you'll locate the area of interest (Samut Songkhram province, Thailand) and add Landsat satellite imagery from ArcGIS Living Atlas of the World. NASA's Landsat satellites have been taking pictures of the planet for almost 50 years. As satellite imaging technology has improved, so have the quality and types of data collected. This massive archive of images has been compressed into one data layer that can be viewed on ArcGIS Online.
Locate the study area
You'll locate Samut Songkhram province on a map in ArcGIS Online.
- Sign in to your ArcGIS organizational account.
If you don't have an organizational account, you can sign up for an ArcGIS free trial.
- Click Map.
Map Viewer opens. The map extent is set to the default extent of your organization.
- In the search box to the upper right of the map, type Samut Songkhram, THA. Click the matching location when it appears below the search box.
The map changes to show Samut Songkhram city. A pop-up automatically appears and confirms the location.
- Close the pop-up and use the zoom tools in the upper left corner of the map to display the whole province of Samut Songkhram.
Add administrative boundaries and Landsat data
Every map starts with a basemap, which provides geographic context for the data you want to display on the map. Since you'll be adding satellite imagery to the map, the basemap and administrative boundaries won't be visible. You'll add a layer of administrative boundaries so you can show the extent of Samut Songkhram province while also showing the imagery. Both of the layers you add can be found in Living Atlas. Living Atlas is the foremost collection of authoritative, ready-to-use global geographic information ever assembled. The themed and publicly shared content in Living Atlas can be accessed using ArcGIS Online map tools. Next, you'll add Living Atlas data to your map.
- To the upper left of the map, click Add and click Browse Living Atlas Layers.
The Living Atlas pane appears. It shows a list of all Living Atlas layers. You can filter the list by specific categories to more easily find the layer you want.
- Click the Filter button.
- In the Filter pane, click Only show content within map area.
- Click Categories, and in the menu, select Boundaries.
- For World Boundaries and Places (careful not to pick Alternate), click the Add button.
The layer is added to the map. The name of the layer is added to the Contents pane and the Living Atlas pane remains open. Next, you'll add the Landsat imagery layer.
- To close the Filter pane, click the X located at the upper right corner of the pane.
- In the Living Atlas pane, in Search for layers, type Multispectral and press Enter.
Among the search results is the Multispectral Landsat layer.
- Add the Multispectral Landsat layer to the map.
The layer is added to the map and the name of the layer is added to the Contents pane.
- Click the Back button to close the Living Atlas pane.
- In the Contents pane, click the World Boundaries and Places layer. Click the three vertical dots on the left side to drag the layer above the Multispectral layer.
You can now see both the imagery and the administrative boundaries.
Save the map
Next, you'll save your map and give it metadata.
- On the ribbon above the map, click the Save button and click Save.
- For the title, type Land Use Change in Samut Songkhram, Thailand.
- For the tags, type the following words and press Enter after each one:
- For the summary, type This map is a collection of images showing four decades of vegetation change in Samut Songkhram, Thailand.
- Click Save Map.
The map is saved with the specified title, tags, and summary.
You've created a map that will serve as a foundation for your presentation on land-use change in the province of Samut Songkhram, Thailand. Saving the map frequently will ensure you don't lose any progress. Next, you'll delve into the historical collection of the Multispectral Landsat layer and create a time animation to show certain images in chronological order.
Show imagery over time
The multispectral Landsat layer that you added to the map contains all the images captured by the Landsat satellites since the program began. As such, the layer can be time-enabled and filtered to select out and display only the images you need for your animation.
Next, you'll enable the time capabilities of the Multispectral Landsat imagery layer. Then, you'll configure a time animation to show historical images at an appropriate speed. You'll filter the dataset to use only specific, relevant, and high-quality images in your animation. It will also be important to select images from approximately the same time of year (within a three-month period) to accommodate seasonal changes in moisture and vegetation health. Finally, you'll emphasize vegetation in the imagery by changing its spectral bands to color infrared. Doing so will make the distinction between types of land use more apparent to your audience. Then you'll identify a region of Samut Songkhram that has experienced significant land-use change for your web app.
Enable time animation
First, you'll enable the time function for the layer. Turning on this functionality allows you to search through 40 years of satellite imagery for your study area.
- In the Contents pane, point to the Multispectral Landsat layer. Click the More Options button and choose Enable Time Animation.
The time animation toolbar appears at the bottom of the map window. The map also changes to show only imagery within the first date range on the timeline: July 24, 1972, to July 24, 1977. Your map viewer turns a color, such as white or blue, because of an error in capturing the first image of this area.
The Landsat program began in 1972, and early Landsat imagery can often be of poor quality or, in this case, show only blank tiles. Later, you'll filter this and other problematic images out of the dataset so only high-quality images are shown. First, you'll look at all of the images to see which ones might be useful for your presentation.
- On the time animation toolbar, click the Play/Pause button.
The timeline plays, cycling through all available images in chronological order. The speed at which the animation progresses is not ideal for observing changes, so you'll change the default settings of the time animation tool to lower the playback speed.
Some images may not load before the timeline continues to the next image. You may need to play the animation more than once to see all of the images.
- When you are finished watching the time animation, click the Play/Pause button again to pause the animation.
Configure the time animation tool
In this section, you will change the default settings in the time animation toolbar to play the animation at an appropriate speed, and to display images by decades to start building your presentation.
- On the time animation toolbar, click the Configure button.
The Time Settings window appears. This window allows you to change the playback speed of the timeline so that more or less time will pass before the timeline jumps to the next image.
- Adjust the playback speed to the slowest setting and click OK.
- Play the time slider again.
While the time animation plays more slowly, sometimes the imagery changes even when the time slider does not. The time slider is currently divided into four-year intervals, and it's possible for more than one image to have been taken during these intervals. You'll lower the display interval to show only one image per tick of the timeline. Doing so will cause the time animation to take a long time to span the entire chronology of Landsat imagery, so you'll also narrow the time encompassed by the timeline to show only imagery between 1972 and 1980. Later, you'll look at imagery from the other decades. This way, you can look at the imagery in more manageable 10-year time periods and also choose the best image from each decade to include in your presentation.
- Click the Configure button. In the Time Settings window, click Show advanced options.
The advanced settings give you the option of customizing the time span and display intervals of the animation.
- For Time Span, change the start time to 7/24/1972 12:00 AM and the end time to 1/1/1980 12:00 AM.
- For Time Display, change the display interval to 1 year.
- Click OK. Play the time animation again.
You can also use the Previous and Next buttons to the right of the timeline to switch between the imagery.
Most of the years between 1972 and 1980 have no imagery or imagery of too low quality to use. In 1978, however, the Landsat program captured a usable image of your study area:
You'll use this image in your presentation to show land use during the 1970s. Later, you'll filter the Landsat dataset to include only this layer, as well as a few others. To do that, you'll need to know the layer's acquisition date, or the date the image was captured by the satellite.
- Click the image in the map window to open a pop-up for the image.
The acquisition date for this image was December 15, 1978. You'll use this date in the next lesson when you filter the dataset. First, you'll repeat the process for the 1980s, 1990s, and 2000s to find an image for each decade to use in your presentation. You will also do a search from 2010 until present day to find the most recent high-quality image.
- On a piece of paper (or in a Word document), write the following information:
Remember to select images from the same time of year (within a three-month period). Seasonal differences in rainfall can affect the appearance of vegetation health.
- Click the Configure button again to open the Time Settings window, and click Show advanced options.
- Change the end time to 1/1/1990 12:00 AM and the start time to 1/1/1980 12:00 AM.
- Optionally, you can adjust the playback speed to your preference.
- Click OK. Play the time animation again. Remember to play the animation more than once for the images to appear properly.
After playing the animation once or twice, using the Previous and Next buttons can make it easier to assess the image quality and cloud cover.
The Landsat program did not capture an image for your study area during the 1980s. In your presentation, this decade will appear blank. Fortunately, there are good-quality images in the next three decades.
- Repeat steps 10 through 13 to view the imagery for the 1990s and 2000s and the most recent high-quality images. When you find an image for each time period, remember to click within the study area and record the date in your table. Use the following time settings for each decade:
- Start time: 1/1/1990 12:00 AM
- End time: 1/1/2000 12:00 AM
- Start time: 1/1/2000 12:00 AM
- End time: 1/1/2010 12:00 AM
- Most recent
- Start time: 1/1/2010 12:00 AM
- End time: <Today's date>
After reviewing animations for each time period, you should have images for the following dates:
- Save your map.
Filter the highest-quality images
Next, you'll filter the multispectral layer to display only the best image from each decade.
- In the Contents pane, point to the Multispectral Landsat layer and click the Filter button.
The Filter: Multispectral Landsat window opens. This window allows you to set a filter on the data to only display parts of that data. You can build filters based on attribute values. You'll build a filter based on the Acquisition Date attribute.
- At the top of the window, click the Edit tab.
By default, the Filter function provides two expression boxes to create the filter. You'll use four expression boxes, one for each of the images you chose.
- Click the Add another expression button twice.
You now have four expressions you can use.
- For each of the filter expressions, change the first drop-down menu to Acquisition Date. Confirm that the second drop-down menu is set to is on.
- Change the third drop-down menu in each filter expression to one of the four dates of the images you chose for your presentation: 12/15/1978, 10/24/1994, 12/14/2004, and <Today's date>.
- Click Apply Filter.
The filter is applied, but the images are not shown because the time animation toolbar is still configured to only show images from a small range of dates.
- On the time animation toolbar, click the Configure button and open the advanced options.
- For Time Span, change the start time and end time to show the entire range of available dates.
You can quickly set the start time and end time by dragging the slider handles to the respective ends of the timeline.
- For Time Display, change the display interval to 10 years.
- Click OK.
- Click the Play/Pause button to view the images.
Only the images for the four dates you chose when you created the filter appear. No image appears between 1982 and 1992, because you added no image from this time period to the filter.
Enhance the imagery with infrared
Even with only four images, it's difficult to tell how much land use has changed over time. When viewing imagery in natural color, as you are now, differences between vegetation, land, and water are not always clear. It can be especially difficult to distinguish land-use differences in earlier images, when satellites had less advanced sensors. To better see how land use has changed over time, you'll change the spectral band combinations of the imagery.
Each Landsat satellite captures red, green, and blue wavelengths of visible light to display imagery the way a human eye sees it. However, they also have sensors that capture information not normally visible. The data from these sensors can be combined into different combinations of spectral bands to emphasize different features. For example, infrared sensors show healthy vegetation as bright red and deep water as black. You'll use infrared to better show land-use change.
- Point to the Multispectral Landsat layer, click the More Options button, and choose Image Display.
The Image Display pane appears, allowing you to change the band combination of the imagery.
- For Renderer, choose the Color Infrared with DRA band combination.
- For Image Enhancement, change the Stretch Type to Standard Deviation.
Using the stretch functions will apply different contrast settings to help accentuate clusters of values. The standard deviation setting helps to brighten the red values so that vegetation and water are more distinct.
- Click Apply and click Close.
The image, for July 24, 1972, now shows healthy vegetation as brighter red, and water as darker blue to black.
- Play the time animation again.
As expected, the greatest amount of vegetation loss occurs between 1978 and 1994. From 1994 to 2004, it appears that there was a dramatic decrease in land-use change, which suggests that the 1991 regulations on the aquaculture industry may have been effective in thwarting the spread of shrimp farms. After 2004, some areas even experienced a rebound, transitioning from water back to vegetation. These areas are important to your organization and donors in supporting the idea that education and conservation can result in restoration.
- Zoom to the coastal areas of Samut Songkhram. Play the animation along different sections of the coast. Take note of where you see the most reduction and rebound in healthy vegetation.
The area of Samut Songkhram that has seen the most significant amount of change is in the southernmost portion of the province.
- Zoom in to this area.
In 1978, this area appears as a solid distribution of bright red, or healthy vegetation. Playing the animation through to present day, you'll observe the mass conversion from healthy vegetation to water. Much of the change occurs between the 1978 and 1994 images, which is the result of the uncontrolled growth in the shrimp farming industry. After 1994, the decimation of healthy coastal vegetation appears to have slowed, with some areas even rebounding back from water to vegetation. This is the area that you will use for your web app because it shows potential for successful restoration efforts.
- Save your map.
You've enabled time animation for your data. You looked at images of Samut Songkhram and chose the best image per decade. You then filtered the Landsat data to show only those images. Lastly, you changed the band combination of the imagery to emphasize vegetation and make the differences in land use clearer. Your web map now contains only relevant data for your presentation. Next, you'll create a web app from your map in order to present your findings to potential donors to your nonprofit organization.
Share your results as a web app
To share your findings with donors and your organization, you'll create a web app based on your map. A web app is a customized user interface that showcases your map for a specific purpose, message, and audience. For example, if you just want to display your map, your app only needs a few basic navigation tools. In this scenario, you need to present your map as a time animation series to demonstrate the changes in land use and distribution of vegetation over four decades. To do so, you'll share your new web map so it can be used in time-aware web applications. Additionally, the Multispectral Landsat layer is premium content, so you must enable the layer to be published through your organizational account at the expense of your organization's credits. Finally, you'll customize the application to present and share your results.
Create a time-aware web app
To create a web app, you must first share your map. Then, you can access the configurable app templates.
- If necessary, open your Land Use Change in Samut Songkhram, Thailand web map.
- On the ribbon above the map, click Share.
- In the Share window, check the box to share the map with everyone. You may also choose to share your app with only your organization.
Now that the map is shared, you'll create the web app.
- In the Share window, click Create a Web App.
The Create a New Web App window appears. It includes a gallery of configurable apps, organized into categories based on purpose and functionality. You can use the scroll bar to review the full gallery, or you can filter the apps with the tabs on the left or the search box at the top.
You want your map and time animation to be the primary focus of your app, so you'll choose an app that is time-aware. Since you're only showing imagery, you don't need to show a legend or pop-up information.
- In the search box, type time. Click the Time Aware app to read its description.
If your organization has configured custom galleries, you may not see these same configurable apps.
The description explains that the Time Aware app "presents an interactive view of time-enabled layers." The functionality of this app seems perfect for your data, so you'll choose this one.
- Click Create Web App.
- In the Create a New Web App window, accept the default title, tags, and folder.
- For the summary, type This application shows the patterns of land-use change in Samut Songkhram, Thailand, over the last 40 years.
It's okay if the app has the same title as the map because the two items are different types of content. By default, the app is given the same sharing properties as the map.
- Click Done.
The app opens in its configurable state.
Configure the app
Next, you'll change elements of the app's presentation to better communicate the map's meaning. You'll also add a logo and a link to your organization's website in case users want to learn more. There are several tabs in the Configure window. You'll configure settings on the following tabs:
- General: Choose the web map you want in your app, define the title, and add a supporting dialog box.
- Theme: Define the color scheme and add a logo and URL. Define the time slider color scheme and time control location.
- Options: Choose whether to include a legend, zoom controls, scale bar, and share dialog box.
- Time Settings: Define settings for time behavior and time sliders. Specify the format for the date and time display with the option to customize.
- Search: Enable location and attribute search tools.
- On the General tab, uncheck the Display about dialog box.
- Click the Theme tab.
The Theme tab allows you to change the color schemes and add a logo and a link. You'll add your charity's logo, shown below, to clearly connect your app to your organization.
- For Logo image URL, paste the following URL:
You're also able to add a link to your charity's website, so that when users click the logo they are directed to a site where they can learn more about your organization's goals and programs. For the purposes of this project, you'll leave this blank.
- At the bottom of the Configure window, click Save to save your configuration and preview the app.
Your custom logo is added and the About button no longer appears.
In the next section, you can set the location and color scheme of the time slider.
- Change Time control location to Bottom right, and accept the default color scheme.
- Click the Options tab.
The map displays only satellite imagery and does not contain any symbology, so the map doesn't require a legend.
- Uncheck the Legend box.
- Click the Time Settings tab.
This tab contains a number of options for customizing your time-aware app. The first three boxes control the time behavior in the app. You want users to be able to see the year and control the time animation themselves.
- Check the Display time box, if necessary. Leave the Loop time continuously and Automatically play slider boxes unchecked.
The next box controls the display on the time slider. Choosing to update the time display immediately can slow performance for large datasets, but your dataset is small.
- Check the Update time immediately box, if necessary.
The slider control and navigation options allow you to customize the time slider interface. You can choose to hide the time slider, show navigation buttons, and add tick marks to the slider. You want the audience to see the time slider and to be able to navigate it. Tick marks can be helpful for visualizing the time milestones when controlling the time slider.
- Check the Show navigation buttons, Add tick marks to slider, and Playback Speed Button boxes.
In the Date/Time Format section, you can define how the date and time format appears in your app. Your map emphasizes a large time frame and the important information is the year that the imagery was captured.
- Change the predefined date format to show only the year. You may also choose to customize your date format.
- Click the Search tab. (You may need to click the right arrow to show more tabs.)
- Uncheck the Enable search tool box.
The search tool allows your audience to search for addresses or other locations. Your map is about this particular study area, so you do not want your audience to navigate away.
- Click Save to save your configuration and preview the app.
- Click the Play/Pause button to run the animation, or click the forward and backward navigation tool to compare the images.
- On the time slider, click between the two slider handles and drag right and left to move more seamlessly between the images for the other time periods.
- At the bottom of the window, click Close.
When you close your app, you are automatically taken to the item page. Before sharing your application, you should add metadata about your app. Metadata allows users to learn more about your map, such as data sources and size.
Edit the item details
The item page allows you to provide supporting information about your app, control the sharing options, delete or move the application, change owners, track usage, and attach code for embedding in websites, and you can also access the app configuration tools from here. You're going to add information about your app so that users who find your app can learn more about its context.
- For Description, click Edit, and type the following description:
Uncontrolled growth of shrimp farms in the 1980s resulted in the decimation of valuable mangrove ecosystems. In the early 1990s, laws and regulations were implemented which slowed the destruction of the remaining healthy vegetation along the coast. In recent years, some areas have had success with restoration efforts. These areas should be the focus of continued conservation education and monitoring practices.
- Click Save.
- For Credits (Attribution), click Edit, and type USGS, Landsat NASA. Click Save.
In this lesson, you created a map with Landsat imagery and enabled time to view the layer's large stores of chronological data. Then, you filtered the layer to display only four key images to show land-use change patterns in Samut Songkhram, Thailand, over the last 40 years. Lastly, you shared your map as a web app and configured it to the needs of your organization. The app can be shared by email or social media and can also be embedded in your organization's website.
A similar map can be made for any region in the world using the Multispectral Landsat layer. Experiment with other band combinations to enhance the features important to your study. The time animation tools are essential to representing historical imagery, while the filter function allows you to sift through thousands of images captured by NASA satellites.
You can find more lessons in the Learn ArcGIS Lesson Gallery.