Discover dynamic imagery and create a web map
Dynamic imagery is imagery that is hosted online and can be easily added to your project for exploration and analysis. For instance, all the Landsat imagery you'll be using in this lesson is stored in the cloud through the Amazon Web Services (AWS) cloud. This means the imagery will be accessed dynamically through your internet connection without the need to download and store the imagery locally. Also, all the visual renderings and image computations will be done on demand in real time. In other words, everything you see on your screen will be dynamically generated from the source Landsat repository on AWS without the need to precompute and store separate imagery products.
To explore the Kilauea 2018 volcanic eruption, you'll look for suitable imagery in ArcGIS Living Atlas of the World. You'll then open a dynamic imagery layer in ArcGIS Online, and save a web map with the layer you have selected.
Discover dynamic imagery layers
ArcGIS Living Atlas of the World is a large collection of geographic information from around the globe, and it includes many dynamic imagery layers. You'll use the ArcGIS Living Atlas website to browse, filter, and discover ready-to-use dynamic imagery.
- In a web browser, browse to the ArcGIS Living Atlas of the World website.
On the home page, you'll find a search bar where you can begin searching for content by keywords.
- Type dynamic imagery in the search bar and click the search button (or press Enter) to initiate the search.
Initiating the keyword search brings you into browse mode, displaying all matching content items. From this point, you can refine your search results by using the various filtering options available.
- For the Imagery categorical filter, click the drop-down arrow and check the box for Multispectral Imagery.
The results update to show only the items containing the keywords dynamic imagery in the Multispectral Imagery category.
- Scroll down the list of results and locate the Multispectral Landsat imagery layer.
- Read the item card summary.
The discovery path in this section was provided to demonstrate some of the available filtering capabilities on the ArcGIS Living Atlas website. As an alternative approach, try starting with a keyword search for Landsat or Multispectral Landsat to see how that affects your discovery experience. As with most search engines, the more precise you are with your keywords, the shorter your path to discovery.
Review item details
When you have found an imagery layer of interest, it is a good idea to review the item details to help determine whether the content and capabilities meet your requirements.
- In the ArcGIS Living Atlas search results, hover over the thumbnail of the Multispectral Landsat item, and click View item details.
You'll now determine whether the Multispectral Landsat layer is a good candidate for exploring the Kilauea volcanic eruption of 2018.
- Use the item description to answer the following questions:
- Does the imagery cover the location of interest, Kilauea Volcano, Hawaii?
Check the section on Geographic Coverage.
- Does the imagery cover temporal coverage of interest, 2018?
Check the section on Temporal Coverage.
- Can individual images be selected based on image capture (acquisition) date?
Check the section on Image Selection/Filtering.
- Does the imagery provide a variety of spectral bands for visual rendering and analysis?
Check the sections on Visual Rendering and Multispectral Bands.
From the information you found, you conclude that the Multispectral Landsat layer is a good candidate for your purpose. You'll now add it to an online map.
Create a web map
With your target dynamic imagery layer identified, you are now ready to open it in ArcGIS Online and save your web map in your ArcGIS Online account.
- On the Multispectral Landsat item details page, click Open in Map Viewer Classic.
Depending on your organizational and user settings, you may have opened Map Viewer. ArcGIS Online offers two map viewers for viewing, using, and creating maps. For more information on the map viewers available and which to use, please see this FAQ.
This lesson uses Map Viewer Classic.
- If necessary, on the ribbon, click Open in Map Viewer Classic.
The Multispectral Landsat map appears in Map Viewer Classic.
- Sign in to your ArcGIS organizational account or into ArcGIS Enterprise using a named user account.
If you don't have an organizational account, you can sign up for an ArcGIS free trial.
- On the ribbon, click Save and choose Save As.
- In the Save Map window, enter the following:
- For Title, type Kilauea Eruption Event 2018 and add your initials or name.
- For Tags, type Landsat and Kilauea and press Enter after each tag.
- For Summary, type Kilauea Eruption Event 2018 or a more detailed summary of your choice.
- Click Save Map.
So far in this lesson, you discovered dynamic imagery through the ArcGIS Living Atlas of the World website and saved a dynamic imagery layer to a web map.
Next, you'll continue to prepare your data for the purpose of exploring the Kilauea 2018 eruption. You'll do that by applying some of the temporal and spectral capabilities of dynamic imagery layers.
Apply dynamic imagery capabilities in ArcGIS Online
For now, your ArcGIS Online map contains a single layer, the Multispectral Landsat dynamic imagery layer. It spans 40 years of Landsat imagery, but, by default, it shows only the most recent imagery available in the archive. It also uses a default spectral band combination. Using some of the temporal and spectral capabilities of dynamic imagery layers, you'll select individual images from before, during, and after the eruption event. You'll also apply different spectral band combinations to unlock greater insights into the Kilauea 2018 eruption.
Add a lava flow extent layer
The first thing you need to do is establish your working area, so that your map focuses on the Kilauea eruption site. You'll use a feature layer that delineates roughly this area of interest (A.I.).
You could use a layer that you have created yourself, but in this lesson, you'll search and load a layer that was prepared for you and is hosted in ArcGIS Online.
- If necessary, sign in to ArcGIS Online, browse to Content, and open your Kilauea Eruption Event 2018 web map.
- From your map, click the Add button and choose Search for Layers.
- In the content search pane, click My Content and choose ArcGIS Online.
- In the search bar, type Kilauea 2018 lava owner:Learn_ArcGIS and press Enter.
- On the only result that appears, click the Kilauea 2018 Lava Flow Extents layer name.
The item details pane for the layer appears. You can read more details about the layer in the pane, including when it was last updated, the feature layer owner, and a description of what the layer may include.
- In the details pane for Kilauea 2018 Lava Flow Extents, click Add to Map.
The map now displays the new layer, and it is automatically zoomed in to the extent of that new layer.
The imagery displayed on your map may somewhat differ from the image above. New imagery is regularly added to the Multispectral Landsat layer (about every two weeks), and you are currently seeing the most recent imagery available.
- Close the details pane, and in the Add layer pane, click the back arrow to return to the map Contents pane.
Next, you'll save the map.
- On the ribbon, click the Save button and choose Save.
Choose a band combination
The Multispectral Landsat imagery layer includes a number of spectral bands, which can be combined in different ways to better visualize the features of interest in the imagery. By default, the layer is set to the Agriculture band combination, which is not the most relevant for your exploration of a volcanic eruption.
You'll change the rendering on the Multispectral Landsat layer to Natural Color with DRA. This band combination will be a good basis to start your exploration of the volcanic eruption.
The Natural Color band combination utilizes the red, green, and blue bands. Together, these 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.
DRA stands for Dynamic Range Adjustment. When DRA is on, the relative brightness or darkness of each pixel is optimized based on the pixel values in the current extent, not all pixels in the layer.
- In the Contents pane, hover over the Multispectral Landsat layer, click More Options, and choose Image Display.
The Image Display pane appears.
- On the Image Display dialog box, for Renderer, click the drop-down menu, and choose Natural Color with DRA.
- Click Apply.
The Natural Color with DRA rendering applies.
- In the Image Display pane, click Close to return to the map Contents pane.
Select images before, during, and after the volcanic eruption
You'll now select images that correspond to your dates of interest before, during, and after the Kilauea 2018 volcanic eruption. The eruption started on May 3, 2018, and subsided around mid-August that same year. The images you'll select are as follows:
- Before the eruption—3/27/2018
- During the eruption—7/17/2018
- Close to the end of the eruption—8/2/2018
- Six months after the eruption—2/26/2019
In the Multispectral Landsat layer, there is a default filter that helps define the imagery displayed by default. You'll first remove that filter to have access to the full temporal archive of Landsat images that spans several decades.
- Hover over the Multispectral Landsat layer and click Filter.
The Filter: Multispectral Landsat window appears.
- Click Remove Filter.
Next, you'll select the imagery for your first date, 3/27/2018, using the Image Filter capability.
- Hover over the Multispectral Landsat layer, click More Options, and choose Image Filter.
The Image Filter pane appears.
This tool lists images available in your layer according to certain criteria. By default, the criterion selected should be the Acquisition Date attribute, which contains the date when the images were captured.
- In the Image Filter pane, verify Attribute is set to Acquisition Date.
This is the correct criterion for your purpose; however, the filter is set to show only a few very recent images. You'll need to change the range of dates in the time slider.
The Image Filter capability is spatially aware and will only return images that intersect the spatial extent of your current view.
But first, the time of day is not necessary for this exercise and the display of dates is cleaner without time stamps, so you'll remove them.
- Click the Format field values button.
- In the Format field values window that appears, uncheck the Show time check box, and click OK.
Next, you'll adjust the time slider range.
- Click the time slider to add a handle. Drag the handles to span from February 2018 to present.
The list of image results now starts in February 2018.
- Under Image Filter Results, scroll and find the two images where Acquisition Date is equal to 3/27/2018.
As you hover over an item in the list, you see a preview of the extent of that image. You can see that the second image (ID starting with LC08_L1TP_062047) completely covers the lava extent polygon, and the first and third images (ID starting with LC08_L1TP_062046) do not. You'll choose the second image.
- Select the first image (ID starting with LC08_L1TP_062047) by checking the check box. Click the Add as a New Layer button below.
A brief pop-up message appears over the map indicating that a layer was created with the selected images.
- At the top of the Image Filter Results list, check and uncheck the Select All check box to clear the selection.
You'll now select images for three additional dates.
It is important that you confirm coverage before making each selection and deselect each image after adding it as a layer to your map. The Image Filter Results will show you how many images you have selected.
- Repeat the same image selection process for the following dates:
- When you have added one image from each of the specified dates, click Done to return to the Contents pane.
- The four additional layers are in the Contents pane.
If you inadvertently added an additional or wrong layer, you can hover over that layer, click More Options, and choose Remove. Use Image Filter to add the correct layer.
Next, you'll rename the four new layers with a more descriptive name.
- Hover over the 2/26/2019 layer, click More Options and choose Rename.
- In the Rename window that appears, replace the existing text with Landsat Natural Color (2/26/2019) and click OK.
- Similarly, rename the three other new layers, maintaining their various acquisition dates.
- Save your map.
You have created layers corresponding to your four relevant dates. All those layers are all set to the Natural Color band combination. Next, you'll observe them.
Explore Natural Color imagery of the volcanic eruption
You'll now observe the imagery that shows your area of interest before, during, and after the volcanic eruption.
- In the Contents pane, turn off all layers except Landsat Natural Color (2/7/2018).
The imagery, captured before the eruption, shows the yet-undisturbed landscape. You can distinguish the island's vegetation, some built-up areas, the original volcano extent (in brown), the coast, and the ocean. A few small clouds can be seen toward the top of the extent.
Because of the very bright clouds, DRA can adjust the rest of the landscape to appear rather dark. For a quick solution, pan a bit southward so the clouds are mostly out of the extent. The DRA will immediately adjust the brightness, resulting in a clearer view of the island's features.
When done observing the layer, click the Default Extent button (home button) on the map to go back to the original extent.
- Turn on the next layer, Landsat Natural Color (7/17/2018).
On this date, the eruption is in full force, and the imagery mostly shows a thick layer of smoke.
- Turn on the Landsat Natural Color (8/2/2018) layer.
The imagery just a couple of weeks later shows the eruption is subsiding. Smoke is still present, but some patches of the land can be seen.
- Turn on the Landsat Natural Color (2/26/2019) layer.
Six months after the eruption, you can see the land and the ocean clearly again. The lava flows, now cold, can be seen in brown.
- Turn off all layers except Landsat Natural Color (2/7/2018) and Landsat Natural Color (2/26/2019).
- Switch between these two layers by turning Landsat Natural Color (2/26/2019) on and off.
Notice the before and after differences, including the expanded coastline, created by the volcano lava.
While the natural color band combination is a good option for a first exploration of this imagery, the thick smoke present on some of the images makes it difficult to see any details. To gain more insight, you'll create supplementary layers for the two smoke-filled images, and set them up with a different band combination.
Create smoke-penetrating SWIR layers
You'll create copies for the two Landsat Natural Color layers showing the active eruption and set them to the shortwave infrared (SWIR) band combination. This band combination has the property of penetrating smoke, which will allow you to better see what is happening on the ground under the thick smoke.
This Landsat imagery includes two SWIR spectral bands (SWIR 1 and SWIR 2), which are useful in measuring relative moisture variations in both soil and vegetation and distinguishing different geologic rock formations, and are capable of penetrating smoke and thin clouds. The Short-wave Infrared band combination combines the three bands, SWIR 2, SWIR 1, and red.
First, you'll make a copy of the layers Landsat Natural Color (7/17/2018) and Landsat Natural Color (8/2/2018), and you'll rename them.
- Hover over the Landsat Natural Color (7/17/2018) layer, click More Options, and select Copy.
A copy of the layer named Landsat Natural Color (7/17/2018) – copy is added to the Contents pane.
- Point to the Landsat Natural Color (7/17/2018) – copy layer, click More Options, and choose Rename.
- Rename the layer Landsat SWIR (7/17/2018) and click OK.
- Similarly, create a copy of Landsat Natural Color (8/2/2018) and rename it.
For each of the SWIR layers, you'll now change the rendering to Short-wave Infrared with DRA.
- Hover over Landsat SWIR (7/17/2018), click More Options, and choose Image Display.
- In the Image Display pane, for Renderer, choose Short-wave Infrared with DRA.
- Click Apply and click Close to return to the map Contents pane.
- Similarly, change the rendering of Landsat Natural Color (8/2/2018) to Short-wave Infrared with DRA.
- In the Contents pane, turn on all the layers.
- Drag each SWIR layer down the list of layers and drop it above the Natural Color layer with the same date.
Click and drag the three nodes to the left of the feature layer to move it.
Your layers are now ordered for comparing the SWIR and Natural Color layers.
- Save your map.
You'll now compare the SWIR and Natural Color layers.
- Turn off all layers except for the SWIR and Natural Color layers for 7/17/2018.
- Switch between those two layers and observe how they differ.
The SWIR bands allow you to see through the smoke to see the active lava flow below.
- Turn off the Landsat Natural Color (7/17/2018) layer and turn on the Landsat SWIR (8/2/2018) layer. Switch between the two SWIR layers and observe how they differ.
In the August imagery, you can see that the eruption activity is slowing down.
- Optionally, spend more time exploring the different layers.
You learned some important temporal and spectral capabilities of dynamic imagery layers in ArcGIS Online. You used temporal filtering to select individual images from before, during, and after the eruption event, and added these images as new layers in your map. You also applied different image renderings to your layers. You then explored differences among the images and even peered through smoke to reveal the active lava flows. Next, you'll add the data you have prepared to ArcGIS Pro, a desktop application with extended visualization and analysis tools.
Explore dynamic imagery in ArcGIS Pro
You are now ready to bring your dynamic imagery layers into ArcGIS Pro. This will allow you to apply further visualization and advanced analysis techniques.
Open your web map in ArcGIS Pro
In this section, you'll start ArcGIS Pro and create a new map by opening your previously saved web map.
- Start ArcGIS Pro. If prompted, sign in using your licensed ArcGIS account.
If you don't have ArcGIS Pro or an ArcGIS account, you can sign up for an ArcGIS free trial.
- Click Start without a template.
- On the ribbon, on the View tab, in the Windows group, click Catalog Pane.
- In the Catalog pane, click Portal. If necessary, use the search bar and locate your Kilauea Eruption Event 2018 layer. Right-click your map and click Add And Open.
It may take a few minutes to create and load the map in ArcGIS Pro.
When you open an existing web map in ArcGIS Pro, the content and settings from your web map have been imported into ArcGIS Pro, and there is not a dynamic link between the map created in ArcGIS Pro and the original web map. This means that changes made in ArcGIS Pro are not reflected in the original web map, and changes in the original web map will not be dynamically reflected in the ArcGIS Pro map. To see any changes saved to the web map, you would need to once again open the web map in ArcGIS Pro, resulting in a new map in ArcGIS Pro.
In the Contents pane, you'll see each of the layers you previously defined and saved in your web map.
- In the Contents pane, for each imagery layer, collapse the band designations by clicking the triangle to the left of each layer, to make the list more compact.
You'll also notice a time animation bar toward the top of your map view.
- Hover over the time bar and minimize it by clicking the collapse button at the top of the bar.
Now, you'll save your ArcGIS Pro session as a new project.
- On the Quick Access Toolbar, click the Save button.
- In the Save Project As window, browse to a location of your choice, such as the Documents folder. For Name, type Kilauea 2018 and click Save.
As part of the end-to-end workflow of this lesson, this section demonstrated adding dynamic imagery content to ArcGIS Pro through a web map. However, it is not always necessary to create a web map to use online content. The same dynamic Multispectral Landsat imagery layer used in your web map can also be loaded directly from ArcGIS Living Atlas into ArcGIS Pro. To access all the ArcGIS Living Atlas content, go to the Catalog pane, click Portal, and click Living Atlas.
Use the Swipe tool
ArcGIS Pro has swipe capability, which is convenient for comparing two layers in detail. You'll visually explore the differences between two images using this tool.
- In the Contents pane, turn off all the layers except for the Landsat SWIR (7/17/2018) and Landsat Natural Color (7/17/2018) layers. Click Landsat SWIR (7/17/2018) to select it.
- On the ribbon, on the Image Service Layer tab, in the Compare group, click Swipe.
- Drag your mouse pointer over the map from top to bottom to reveal the Landsat Natural Color (7/17/2018) layer below the Landsat SWIR (7/17/2018) layer.
You can also swipe from left to right.
In Swipe mode, if you hold the Shift key, you can switch between the two layers when you click the map.
- Turn on the two 8/2/2018 Landsat layers and use the Swipe tool to compare them.
Swipe requires at least two layers to be turned on and the topmost layer to be selected.
- On the ribbon, on the Map tab, in the Navigate group, click Explore to exit the Swipe tool.
- Press Ctrl+S to save your project.
You added your web map to ArcGIS Pro, preserving the dynamic imagery settings you configured earlier, and explored some visualization tools. Your layers are now ready for the many possible imagery analysis workflows that ArcGIS Pro enables.
In this lesson, you discovered dynamic imagery layers in ArcGIS Living Atlas, selected images based on acquisition date, and chose band combination renderings. You created layers in ArcGIS Online, and imported those layers into ArcGIS Pro for further manipulation and analysis.
You will find many such imagery analysis workflows on the Introduction to Imagery & Remote Sensing website.