Estimate storage capacity with drone imagery

The Yucaipa Valley Water District(YVWD) needs to estimate the storage capacity of a storm water retention basin. On-site measurements cost time, money, and labor, so the district captured aerial imagery with a drone to help estimate the basin's volume.

In this lesson, you'll convert drone imagery into elevation layers using ArcGIS Drone2Map. Then, in ArcGIS Pro, you'll use geoprocessing tools to estimate the basin's volume. Finally, you'll share the results with your YVWD colleagues in ArcGIS Online.

This lesson was last tested on July 7, 2021, using ArcGIS Drone2Map 2.3 and ArcGIS Pro 2.8. If you're using different versions of these applications, you may encounter different functionality and results.

Requirements

• Publisher or Administrator role in an ArcGIS organization (get a free trial)
• ArcGIS Drone2Map
• ArcGIS Pro
• ArcGIS Spatial Analyst extension

Generate the raster data

The Yucaipa Valley Water District (YVWD) took aerial imagery of its water recycling facility using a drone. The water recycling facility includes a storm water retention basin, which is the feature of interest in this lesson. First, you'll use ArcGIS Drone2Map to convert the imagery into the following data products:

• Orthomosaic: An image composed of many smaller images aligned together
• Digital surface model (DSM): An image that shows the elevations of an area, including structures and vegetation
• Digital terrain model (DTM): An image that shows the ground elevation of an area, not including structures and vegetation

Note:

Because the drone images overlap partially, Drone2Map can do some computations on the back end to derive tridimensional elevation information. This process uses the structure from motion technique.

These datasets will provide an accurate map of the facility and the elevation data necessary for calculating the volume of the storm water retention basin.

Download the drone imagery

The images that the drone captured are stored online in a zipped file folder. You'll download the folder, unzip its contents, and look at some of the images before you add them to a Drone2Map project.

1. Go to the yvwd_images item page and click Download.
   

   The .zip file downloads to your computer.

2. Locate the downloaded file. Right-click the file and extract it to a location where you can easily find it, such as your Documents folder.
3. Open the folder.

   

   The folder contains 19 images.

4. Double-click the image named DJI_0984.

   A preview appears. The image shows a top-down view of the storm water retention basin that you'll measure later. The basin is empty, because each summer the YVWD cleans it out to get ready for the next rainy season. However, from this image, it's difficult to tell how deep the basin is.

   

5. Close the preview.

Create a Drone2Map project

Next, you'll create a project in Drone2Map and add the drone images to a map.

1. Open ArcGIS Drone2Map.

   Note:

   If you don't have Drone2Map, you can sign up for a free trial.

2. If prompted, sign in using your licensed ArcGIS account.

   Note:

   If you don't have an organizational account, you can sign up for an ArcGIS free trial.

   The application opens. You can choose from several project templates based on the type of data you'll create. The data types that you are interested in, which are Orthomosaic, DTM, and DSM, belong to the 2D category, because they are made of 2D rasters. A raster is a grid in which each cell (or pixel) contains one value. For instance, in the case of the DTM or the DSM, each cell contains a terrain elevation value.

3. For Select Project Template, click 2D Full and click Next.

   

   Next, you'll specify some of the project's parameters and choose the images to use in the project.

4. For Give Your Project a Name, type YVWD Recycled Water Facility.
5. Click Browse to choose the location on your computer where the project data will be stored.
6. Click Add Folder.

   

   The Browse for Image Folder window appears.

7. Browse to and select the downloaded folder, yvwd-images, that contains your images. Click OK.

   The images are loaded into the table.

   

   Each image has a Lat [Y] (degrees latitude), Long [X] (degrees longitude), and Alt [Z] (height) attribute. These geographic attributes were stored by the drone when it captured each image, allowing the images to be located on a map. For these images, the default coordinate system is acceptable.

8. Click the Create button.

   A map is created with 19 points, representing each image. The points are connected by orange lines; these lines represent the flight path that the drone took to capture the images. The drone images themselves do not display on the map.

   

Process the data

To convert the images into data products that you can use in analyses, you need to process them. Because you chose the 2D Full template, the project is automatically set to generate an orthomosaic, a DSM, and a DTM.

Note:

It is possible to choose custom settings by clicking Options on the ribbon's Home tab, but for this lesson, you will just go with the defaults.

1. On the ribbon, ensure that the Home tab is selected. In the Processing group, click Start.

   

   The processing begins.

   Note:

   The process may take 15 minutes or more to complete.

2. You can monitor the process status by looking at the progress bar in the lower right of the screen.

   

   Once the processing finishes, three new datasets are added to the Contents pane: an Orthomosaic, a Digital Surface Model (DSM), and a Digital Terrain Model (DTM).. The datasets are also added to the 2D map. Currently, you can only see the Orthomosaic, which represents the whole area as an image in natural colors.

   

3. In the Contents pane, uncheck Orthomosaic.

   

   The DSM is now the visible layer. The DSM is a raster representing the elevation of the area, including structures and vegetation.

   

   Note:

   Your layers may have been added in a different order so that the DSM is below the DTM.

4. In the Contents pane, uncheck Digital Surface Model..

   The DTM is now the visible layer.

   

   The DSM and DTM look relatively similar in this case, but the DTM is smoother and devoid of buildings and vegetation. In both of them, you can see the shape of the storm water retention basin quite clearly.

   Next, you'll look at these three layers in 3D.

5. Close the Manage pane and click the 3D Map tab.

   

6. On the map, click the Show Full Control arrow of the Navigator tool to expand it.

   

7. Explore the 3D scene. Use the inner wheel of the Navigator tool to tilt and rotate the scene. Use the mouse scroll wheel to zoom in and out, and drag with the mouse to pan.

   

   Note:

   For more help with exploring 3D scenes, refer to the Navigation help topic.

8. Turn the Orthomosaic, DTM, and DSM layers on or off to visualize each of them, paying special attention to the storm water retention basin.

   

   The three products appear to be sunken in the ground because the DTM used as the primary elevation surface only covers a small area. Outside of the study area, the WorldElevation3D/Terrain3D surface is used instead. The difference in elevation between the two surfaces is due to a difference in resolution. The DTM (which appears sunken) is the more accurate surface.

   In the 3D view, the shape and details of the water retention basin are again quite precise.

9. Press Ctrl+S to save your project.

In this module, you converted drone imagery into three data products: an orthomosaic, a DSM, and a DTM. Next, you'll compute the volume of the basin.

Estimate volume

You'll now calculate the basin's total capacity. To do so, you'll use geoprocessing tools in ArcGIS Pro.

Note:

Drone2Map itself has a Volume calculation tool, which you can find on the ribbon, on the Analysis tab. This is a great tool to get a quick estimate of a volume, based on a polygon boundary you draw in the 2D map, and it works particularly well when the boundaries of the feature of interest are well defined. However, given the shape of the storm water retention basin, it is not clear where its boundaries are precisely, so you'll get a more accurate measurement by using geoprocessing tools in ArcGIS Pro.

Open the project in ArcGIS Pro

First, you'll convert your Drone2Map project to an ArcGIS Pro project.

1. In Drone2Map, click the 2D Map tab.
2. In the Contents pane, make sure that the Orthomosaic, Digital Surface Model, and Digital Terrain Model layers are turned on. Turn off and collapse Project Data and Map Notes, as you won't need those layers anymore.

   

3. Press Ctrl+S to save your project.
4. On the ribbon, on the Analysis tab, in the Tools group, click Open in ArcGIS Pro.

   

5. In the Open in ArcGIS Pro window, click Yes.

   ArcGIS Pro opens.

6. If prompted, sign in using your licensed ArcGIS account.

   Note:

   If you don't have ArcGIS Pro or an ArcGIS account, you can sign up for an ArcGIS free trial.

   All of the elements that were present in your Drone2Map project are now present in your ArcGIS Pro project.

   

7. Close Drone2Map.

   Note:

   If you ever need to close and reopen the project in ArcGIS Pro at some point, go to the YVWD Recycled Water Facility project folder on your computer and double-click YVWD Recycled Water Facility.aprx.

Fill sinks with a geoprocessing model

To compute the basin volume, you'll use the DTM as your primary dataset, as it provides precise elevation data for the entire basin surface.

The first geoprocessing tool you'll use is Fill. This tool fills any sinks it finds in elevation data and produces a new raster with the updated elevation values. Sinks are areas where the elevation is lower than all areas around it: water that flows into a sink won't be able to flow out of it. The storm water retention basin is a sink. By filling it, and then comparing the filled elevation to the basin's original elevation, you can determine the volume capacity.

How Fill works: the original DTM (in green) and the filled sink (in red) are shown.

1. On the ribbon, on the Analysis tab, in the Geoprocessing group, click Tools.

   

2. The Geoprocessing pane appears. You can use this pane to search for tools.
3. In the search box, type Fill. In the list of results, click the Fill tool.

   

4. In the Fill tool pane, set the following parameters:
   • For Input surface raster, choose DEM Products\Digital Terrain Model.
   • For Output surface raster, change the output name to Fill_Result, at the end of the YVWD Recycled Water Facility.gdb path.

   

5. Click Run.

   When the process is complete, the new layer, Fill_Result, appears in the Contents pane and on the map. The Fill tool filled all the depressions in the DTM elevation surface. Next, you'll use the Cut Fill tool, which calculates the volume change between two surfaces: in this case, the original Digital Terrain Model and Fill_Result layers.

6. In the Geoprocessing pane, click the Back button.

   

7. Search for and open the Cut Fill tool.

   Note:

   You can use the Cut Fill tool from either 3D Analyst Tools or Spatial Analyst Tools.

8. Set the following Cut Fill tool parameters:
   • For Input before raster surface, choose DEM Products\Digital Terrain Model.
   • For Input after raster surface, choose Fill_Result.
   • For Output raster, change the output name to Volume_Raster, at the end of the YVWD Recycled Water Facility.gdb path.

   

9. Click Run.

   When the process is complete, the new Volume_Raster layer appears. On it, all areas that were filled are identified with the color red.

   

   You'll now open the Volume_Raster attribute table to identify the retention basin's volume.

10. In the Contents pane, right-click Volume_Raster and choose Attribute Table.

    

    The attribute table contains a field, Volume, with volume measurements for each sink. You'll sort the sinks from largest to smallest volume.

    Note:

    The volume values are all expressed as negative numbers because when you used the Cut Fill tool, you subtracted the higher elevation from the lower.

11. Right-click the column header for Volume and choose Sort Ascending.

    

12. Click the cell next to the top row to select it.

    

    This largest sink represents the storm water retention basin. You can see that it is by far the largest volume (about 5,360.6 versus 25.7 for the second-ranked sink): the other filled areas correspond only to tiny sinks caused by minor terrain variations.

    The volume for the basin is 5,360.665928, but the unit is not stated. You'll now identify the unit used.

13. In the Contents pane, right-click the Volume_Raster layer and choose Properties.

    

14. In the Layer Properties window, click Source.
15. Under Data Source, the Vertical Units are set to Meter.

    

    This unit type indicates that the Volume field was calculated in cubic meters. Hence, the volume of the storm water retention basin is approximately 5,360.66 cubic meters.

16. Close the Layer Properties window and the Volume_Raster attribute table.
17. On the ribbon, on the Map tab, in the Selection group, click Clear to remove all selections.

    

Create a polygon feature class

For now, the basin has been only identified in a raster, Volume_Raster. To add to a map, it will be more convenient to have the basin represented as a vector feature, in other words, a polygon that shows the boundaries of the basin. You'll use the Raster to Polygon tool, which converts a raster dataset to polygon features.

1. In the Geoprocessing pane, click the Back button. Search for and open the Raster to Polygon tool.
2. Set the following Raster to Polygon tool parameters:
   • For Input raster, choose Volume_Raster.
   • For Field, keep Value.
   • For Output polygon features, change the output name to Basin_Polygon, at the end of the YVWD Recycled Water Facility.gdb path.
   • Uncheck the Simplify polygons box.

   

3. Click Run.

   A polygon layer is added to the map. The largest polygon represents the basin, but you can also see many small polygons, which represent small sinks, and are irrelevant for your analysis. You'll create a layer that contains only the basin polygon.

4. On the ribbon, on the Map tab, in the Selection group, click Select.

   

5. On the map, click the basin polygon to select it.

   

   Note:

   The color of the layer is chosen at random and might differ from the example image.

6. In the Contents pane, right-click Basin_Polygon, choose Data, and Export Features.

   

7. In the Export Features window, set the following parameters:
   • For Input Features, verify that Basin_Polygon is selected.
   • For Output Location, accept the default, YVWD Recycled Water Facility.gdb. This is the geodatabase where all your layers are being saved in this project.
   • For Output Name, type Retention_Basin.

   

8. Click Run.

   The new layer appears.

9. In the Contents pane, turn off Basin_Polygon, Volume_Raster, and Fill_Result to better see the new layer.

   The Retention_Basin layer contains a single polygon that represents the basin. It displays on top of the orthomosaic imagery.

   

   Next, you'll add some of the missing attribute data to that layer.

10. In the Contents pane, right-click Retention_Basin, and choose Attribute Table.

    

    When the polygon was created, the Volume field was not passed on from the raster. You'll now add it back with the Join Field tool, using the common gridcode attribute to retrieve the right volume value.

    Note:

    The Id and gridcode values are chosen at random and may vary.

11. In the Geoprocessing pane, click the Back button. Search for and open the Join Field.
12. Set the following Join Field tool parameters:
    • For Input Table, choose Retention_Basin.
    • For Input Join Field, choose gridcode.
    • For Join Table, choose Volume_Raster.
    • For Join Table Field, choose Value.
    • For Transfer Fields, choose Volume.

    

13. Click Run.

    The Volume field is now added to the Retention_Basin attributes.

    

14. Press Ctrl+S to save the project.

In this module, you opened several data products representing the storm water retention basin in ArcGIS Pro. Then you used geoprocessing tools, such as Fill and Cut Fill, to estimate the basin's volume.

Share the results

Previously, you estimated the volume of the storm water retention basin. Next, you'll symbolize the basin and configure pop-ups to convey the most relevant information. Then, you'll share the results as a map package.

Style the layer

You intend to share the map as a package, so you'll remove any unnecessary layers. You'll also change the Retention_Basin layer's style to an outline with no fill. That way, users can see the imagery of the basin under the layer.

1. In the Contents pane, right-click the Basin_Polygon layer, and choose Remove.

   

2. Similarly, remove all layers except Retention_Basin, Orthomosaic, and the basemap layers.

   

   Next, you'll change the symbology.

3. Click the symbol under Retention_Basin.

   

   The Symbology pane appears.

4. If necessary, at the top of the Symbology pane, click Gallery.
5. In the list of symbols, click the Black Outline (2 pts) symbol.

   Tip:

   To see a symbol's full name, point to it.

   

   The map updates.

   

   The basin is now symbolized with an outline, and users can see the imagery.

6. Close the Symbology pane.

Configure pop-ups

The Retention_Basin layer is now displaying as desired. To ensure that the user sees meaningful information, you'll configure the pop-up to display only the basin's area and volume.

1. On the map, click anywhere on the retention basin area to display the corresponding informational pop-up.

   

   The pop-up contains a lot of information that isn't necessary for the YVWD staff to see, such as the feature's Id and gridcode attributes. Also, the volume value is negative and its unit of measurement isn't clear.

2. In the Contents pane, right-click Retention_Basin and choose Configure Pop-ups.

   .

   The Configure Pop-ups pane appears. Pop-ups can be configured using expressions. You'll use an expression to convert the area and volume values into the units requested by YVWD.

3. At the bottom of the Configure Pop-ups pane, click Expressions.

   .

4. Click New.

   .

   The Expression Builder window appears. First, you'll add an expression to display the area of the basin in thousands of square feet. This expression will need to do two things:

   • Multiply by 10.7639 to convert from square meters to square feet.
   • Divide by 1,000 to get the area in thousands of square feet.
5. In the Expression Builder, enter the following values:
   • For Name, type Area.
   • For Title, type Area.
   • For Expression, type (or copy and paste) ($feature.Shape_Area*10.7639)/1000.

   

6. Click OK.

   Next, you'll add an expression to show the volume in millions of gallons. This expression will need to do three things:

   • Multiply by 264.172 to convert from cubic meters to gallons.
   • Divide by 1,000,000 to get the volume in millions of gallons.
   • Multiply by -1 to make the number positive.

   You'll use text later to explain the units.

7. In the Configure Pop-ups pane, click New.
8. In the Expression Builder, enter the following values:
   • For Name, type Volume.
   • For Title, type Volume.
   • For Expression, type ($feature.VOLUME*-264.172)/1000000.

   

9. Click OK.

   Both expressions are configured. Next, you'll add the expressions and relevant text to the pop-up.

10. In the Configure Pop-ups pane, click the Back button.

    

    First, you'll change the pop-up title.

11. Click {Id} to edit the title of the pop-up.

    

12. Under Title Options, replace the existing text with Stormwater Retention Basin Capacity. Click the Back button.

    

    Currently, the pop-up content is a list of attribute fields. You'll change it to text that you can customize.

13. Click the Text button.

    

    A Text object is added to the list of pop-up elements.

14. Next to the Text object, click the Edit pop-up element button.

    

15. Delete the current text: Text, and type Area = followed by a space.
16. Click Field and choose Area {expression/Area}.

    

17. Add another space and type thousand square feet.

    Together, it reads Area = {expression/Area} thousand square feet.

18. Press Enter. On the next line, similarly, create the string Volume = {expression/Volume} million gallons.

    

19. Click the Back button.

    Now that you have formatted the pop-up to include the most relevant information, you no longer need to show all of the fields.

20. Next to Fields(8), click the Remove pop-up element button.

    

21. On the map, click the Retention_Basin feature to view its new pop-up.

    

    The retention basin has an area of almost 43,000 square feet and a capacity to hold over 1.4 million gallons of storm water.

    Note:

    Your values may be slightly different.

22. Close the pop-up and the Configure Pop-ups pane. Save the project.

Publish the map

Your map has been symbolized and its pop-ups are configured. Next, you'll publish your results as a map package to ArcGIS Online, where you can share it with the YVWD staff.

1. On the ribbon, on the Share tab, in the Package group, click Map.

   

   The Package Map pane appears.

2. In the Package Map pane, enter the following values:
   • For Name, type YVWD_Recycled_Water_Facility.
   • For Summary, type This map shows the Yucaipa Valley Water District's recycled water facility and stormwater retention basin capacity.
   • For Tags, type Yucaipa, stormwater, and basin.

   

3. If necessary, for Share with, check the box next to your organization.

   You'll analyze the data before sharing it to make sure there are no major errors.

4. At the bottom of the Package Map pane, click Analyze.

   

   No errors or warnings are found.

5. Click Package.

   After a few minutes, the map is successfully packaged and stored on ArcGIS Online.

6. In the Package Map pane, click the Manage the package link to find the package in your ArcGIS Online account.

   

   The YVWD staff will be able to easily access that packaged map and open it in ArcGIS Pro.

7. Close the Package Map pane.
8. Save the project.

In this lesson, you created several data products from drone imagery of a storm water retention basin with Drone2Map and added them to an ArcGIS Pro project. Then, you used geoprocessing tools to estimate the basin's volume. Finally, you configured the map and published it as a packaged map to ArcGIS Online.

You can find more lessons such as this on the Introduction to Imagery & Remote Sensing page.