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Tutorial: Create drone imagery products in ArcGIS Pro using ArcGIS Reality Server

Available with Standard or Advanced license.

In ArcGIS Pro, you can process drone imagery to remove geometric distortions caused by the sensor, platform, terrain displacement, and generate Reality mapping products. With ArcGIS Reality Server, this processing can be performed remotely on your self-hosted enterprise infrastructure, enabling you to leverage multi-machine configuration for distributed processing.

In this tutorial, you will set up a Reality mapping workspace for remote processing of drone imagery. Next, you will perform a block adjustment, followed by a refined adjustment using ground control points. Finally, you'll generate a digital surface model (DSM), true ortho, and 2D DSM mesh using distributed server processing.

ArcGIS Reality for ArcGIS Pro requires information about the camera, including focal length and sensor pixel size, as well as the location at which each image was captured. This information is commonly stored as metadata in the image files, typically in the EXIF header. It is also helpful to know the GPS accuracy. In the case of drone imagery, this should be provided by the drone manufacturer. The GPS accuracy for the sample dataset in this tutorial is better than 5 meters.

Note:

ArcGIS Reality Server is needed to complete this tutorial. To configure a Reality Server, please refer to the Reality Server installation.

Connect to ArcGIS Reality Server

To utilize Reality Server for processing your data in ArcGIS Pro, you need to first connect to the Reality Server.

  1. Open ArcGIS Pro, Click the Project tab on the ribbon and click the Portals page.

    You can also access the portals page from the Manage Portals link in the Sign In menu Sign in.

  2. Click Add Portal.

  3. Enter the URL (https://webadaptorhost.domain.com/webadaptorname) for the portal on the Add Portal dialog box and click OK.

  4. Sign in to the portal by clicking the Options button More or right-click the portal and click Sign in. Enter your username and password.

  5. To make the new connection your active portal, right-click the URL and click Set As Active Portal.

  6. Once you successfully connect to your portal, your username will show up in the top right corner of ArcGIS Pro.

    Portal Connection In ArcGIS Pro

Create a Reality mapping workspace

A Reality mapping workspace is an ArcGIS Pro subproject that is dedicated to Reality mapping workflows. It is a container in an ArcGIS Pro project folder that stores the resources and derived files that belong to a single image collection in a Reality mapping task.

A collection of 195 drone images is provided for this tutorial. The GCP folder contains the Tut_Ground_Control_UTM11N_EGM96.csv file, which contains ground control points (GCPs), and a file geodatabase (GCP_desc.gdb) with a Ground_Control_NAD832011_NAVD88 point feature class identifying the GCP locations at the site.

To create a Reality mapping workspace, complete the following steps:

  1. Download the tutorial dataset. unzip it, and save contents to C:\SampleData\RM_Drone_tutorial.

  2. In ArcGIS Pro, create a project using the Map template.

  3. On the Imagery tab, in the Reality Mapping group, click the New Workspace drop-down menu and choose New Workspace.

  4. In the Workspace Configuration window, type a name for the workspace.

  5. Ensure that Workspace Type is set to Reality Mapping.

  6. Click the Sensor Data Type drop-down menu, and choose Drone.

  7. Click the Basemap drop-down menu, and choose Topographic.

  8. Set the Parallel Processing Factor. This controls the maximum computational resource for distributed processing. It is recommended to use percentage expression. For example, if you have 2 Reality Server nodes, set Parallel Processing Factor to 50% to utilize one machine for block adjustment and reality mapping product generation.

  9. Check Process this image collection on server if you want to use Reality Server.

    Workspace configuration window for drone imagery processing on server

  10. Accept all other default values and click Next.

    The Image Collection window appears.

  11. In the Image Collection window, for Sensor Type, ensure Generic is chosen.

    This option is used because the imagery was collected with an RGB camera.

  12. For Source, ensure File is selected from the drop-down list.

  13. Click Add, browse to the tutorial data location, select the Images folder, then click OK.

    Note:

    Most modern drones store GPS information in the EXIF header. This will be used to automatically populate the table shown below. However, some older systems or custom-built drones may store GPS data in an external file. In this case, you can use the Import button Generic import next to the Geolocation parameter to import external GPS files.

    The Spatial Reference and Camera Model values are automatically populated. The workspace requires a projected coordinate system. The autogenerated, default Workspace Spatial Reference is based on the matching WGS84 UTM coordinates for the images. This projection determines the spatial reference for the ArcGIS Reality for ArcGIS Pro products.

    Drone Image Collection window

  14. Click Next.

  15. In the Lidar Collection window, accept the default values and click Next.

    Lidar collection option

  16. In the Data Loader Options page, for Elevation Source, select Average Elevation from DEM from the drop-down list. The World Elevation Service will be used as the Elevation Source.

    Data Loader Options window

    • If you have access to the internet, the Elevation Source value is derived from the World Elevation Service. This provides an initial estimate of the flight height for each image.

    • If you do not have access to the internet or a DEM, choose Constant Elevation from the Elevation Source drop-down menu and enter an elevation value of 414 meters.

    • The parameter, Image Exclusion Height (m), refers to the image exclusion height, where images having a flight height above terrain that is less than this value will not be included in the workspace.

  17. Accept the default settings in the Data Loader Options window and click Next.

  18. In the Remote Process window, provide description and tags for the image service and click Finish.

    Remote process option of reality mapping workspace

Once the workspace has been created, a Reality Mapping category will be added to the Contents pane, where the image collection image service and derived Reality mapping products service will be stored.

To see the image footprints, you can right click on the Image Collection in the Contents pane > Properties > Display > Check on Display Footprints.

The initial display of imagery in the workspace confirms that all images and necessary metadata were provided to initiate the workspace. The images have not been aligned or adjusted, so the mosaic may not appear geometrically correct. Note: You may need to zoom in close enough to see the image.

A new Reality Mapping tab will be added to the ArcGIS Pro main menu. Clicking this tab will expose a series of tools and workflows dedicated to Reality mapping. In the Product category, all the buttons are unavailable because the images are not yet adjusted.

Perform a block adjustment

After the Reality mapping workspace has been created, the next step is to perform a block adjustment using the tools in the Adjust and Refine groups. The block adjustment first calculates tie points, which are common points in areas of image overlap. The tie points are then used to calculate the orientation of each image, known as exterior orientation in photogrammetry. The block adjustment process may take a few hours depending on your computer setup and resources.

To perform a block adjustment, complete the following steps:

  1. On the Reality Mapping tab, in the Adjust group, click Adjust Adjust.

  2. In the Adjust window, ensure all the Perform Camera Calibration options are checked.

    This indicates that the input focal length is approximate and that the lens distortion parameters will be calculated during adjustment. For drone imagery, these options are checked by default, since most drone cameras have not been calibrated. This option should not be checked for high-quality cameras with known calibration.

    The camera self-calibration requires that an image collection has in-strip overlap of more than 60 percent and cross-strip overlap of more than 30 percent.

  3. Expand Advanced Options.

  4. Ensure Use Orientations from Metadata option is checked.

    This reduces the adjustment duration by using the exterior orientation information embedded in the image EXIF as initial values.

  5. Ensure the Fix Image Location for High Accuracy GPS option is unchecked.

    This option is used only for imagery acquired with differential GPS, such as Real Time Kinematic (RTK) or Post Processing Kinematic (PPK).

  6. Optionally, uncheck Compute Posterior Standard Deviation for Images.

  7. For Image Location Accuracy, choose High from the drop-down menu.

    GPS location accuracy indicates the accuracy level of the GPS data collected concurrently with the imagery and listed in the corresponding EXIF data file. This is used in the tie point calculation algorithm to determine the number of images in the neighborhood to use. The High value is used for GPS accuracy from 0 to 10 meters.

    Adjust tool options

  8. Accept all other defaults and click Run.

    After the adjustment has been performed, the Logs file displays statistical information such as the mean reprojection error (in pixels), which signifies the accuracy of adjustment, the number of images processed, and the number of tie points generated.

    The relative accuracy of the images is also improved, and derived products can be generated using the options in the Product category. To improve the absolute accuracy of generated products, GCPs must be added to the block.

Add GCPs

GCPs are points with known x,y,z ground coordinates, which are often obtained from ground survey, that are used to ensure that the photogrammetric process has reference points on the ground. A block adjustment can be applied without GCPs and still ensure relative accuracy, although adding GCPs increases the absolute accuracy of the adjusted imagery.

Import GCPs

To import GCPs, complete the following steps:

  1. On the Reality Mapping tab, in the Refine group, click Manage GCPs.

    The GCP Manager window appears.

  2. In the GCP Manager window, click the Import GCPs button Import GCPs.

  3. In the Import GCPs window, under GCP File, browse to and select the Tut_Ground_Control_UTM11N_EGM96.csv file, and click OK.

  4. Under Set GCP Spatial Reference, click the Spatial Reference button Browse spatial reference and do the following in the Spatial Reference window:

    1. For Horizontal systems, expand Projected Coordinate System, North America, Zone Series, and UTM (NAD 1983), and choose NAD 1983 UTM Zone 11N.

    2. To define the vertical coordinate system, click the vertical systems tab, expand Vertical Coordinate System, Gravity-related, and World, and choose EGM96 height.

  5. Click OK to accept the changes and close the Spatial Reference window.

  6. Under Geographic Transformations, click the Horizontal tab and choose WGS 1984 (ITRF00) to NAD83 from the drop-down list.

  7. Click the Vertical tab and choose None from the drop-down menu.

  8. Map the GCP fields accordingly under Field Mappings.

    Import GCPs window

  9. Click OK to import the GCPs.

    The imported GCPs are listed in the GCP Manager window, and the relative locations are displayed in the 2D Map view with a red position indicator .

    Imported GCPs on map

  10. Click the drop down next to the Add GCP or Tie Point button in the GCP Manager window and select Semi-Auto Add tie points.

  11. Click one of the GCPs in the table of the GCP Manager window. A list of images containing the GCP will be displayed in the lower panel of the GCP manager window.

  12. Click on one of the listed images and select the exact location of the GCP in the image viewer to add a tie point.

    Using the Semi_Auto GCP option, the tie points for other images are automatically calculated by the image matching algorithm, when possible, indicated by a blue cross next to the image ID. Review each tie point for accuracy. If the tie point is not automatically identified, add the tie point manually by selecting the appropriate location in the image

  13. Repeat step 11 and 12 for the other GCPs.

  14. After each GCP has been added and measured with tie points, select one of the GCPs, right-click, and change it to a check point.

    This provides a measure of the absolute accuracy of the adjustment, as check points are not used in the adjustment process.

  15. After adding GCPs and check points, click Adjust to run the adjustment again to incorporate these points.

    Tie point selection in the GCP Manager window

Review adjustment results

Adjustment quality results can be viewed in the GCP Manager window by analyzing the residuals for each GCP. Residuals represents the difference between the measured position and the computed position of a point. They are measured in the units of the project's spatial referencing system. After completing adjustment with GCPs, three new fields—dX, dY, and dZ—are added to the GCP Manager table and display the residuals for each GCP. The quality of the fit between the adjusted block and the map coordinate system can be evaluated using these values. The root mean square error (RMSE) of the residuals can be viewed by expanding the Residual Overview section of the GCP Manager window.

GCP residuals in the GCP Manager window

Additional adjustment statistics are provided in the adjustment report. To generate the report, on the Reality Mapping tab, in the Review group, click Adjustment Report.

Generate Reality mapping products

Once the block adjustment is complete, 2D and 3D imagery products can be generated using the tools in the Product group on the Reality Mapping tab. Multiple products can be generated simultaneously using the Reality Mapping Multiple Products wizard or individually by selecting the applicable product tool from the Product group. The types of products to be generated depends on various factors including the sensor and data flight configuration. The flight configuration of the sample dataset is nadir, which is ideal for 2D products such as DSM, true ortho, and DSM mesh.

Note:

In this tutorial, two approaches to generate derived products are outlined below. One approach uses the Multiple Products wizard and the second uses the individually named product wizards listed in the Product group. It is recommended that you follow one or the other workflow approach, since doing both workflows is not required for this tutorial.

Generate multiple products using the Reality Mapping Products wizard

The Reality Mapping Products wizard guides you through the workflow to create one or multiple Reality mapping products in a single process. The products that can be generated using the Reality Mapping Products wizard are DSM, true ortho, DSM mesh, point cloud, and 3D mesh. All generated products are stored in product folders of the same name under the Reality Mapping category in the Catalog pane.

To generate products using the Reality Mapping Multiple Products wizard, complete the following steps:

  1. On the Reality Mapping tab, click the Multiple Products button in the Product group.

    The Reality Mapping Products Wizard window appears.

  2. In the Product Generation Settings pane, uncheck the 3D check box.

    In this tutorial, only 2D products are generated.

  3. In the 2D products category, uncheck Digital Terrain Model (DTM) then ensure Digital Surface Model (DSM) is selected.

  4. Click the Shared Advanced Settings button.

    The Advanced Products Settings dialog box appears, where you can define parameters that will impact the Reality mapping products to be generated. For details of the advanced product settings, see Reality Advanced Settings in the wizard.

    The Quality value is automatically set and should not be changed to ensure optimum performance and product quality.

  5. Accept the Pixel Size default settings.

  6. For Product Boundary, click the Browse button Browse, browse to the file geodatabase in the tutorial data location, select Project_bdry, and click OK.

    It is recommended that you provide a product boundary for the following reasons:

    • Define the proper output extent—When you do not define a product boundary, the application automatically defines an extent based on various dataset parameters that may not match the project extent.

    • Reduce processing time—If the required product extent is smaller than the image collection extent, defining a product boundary reduces the processing duration and automatically clips the output to the boundary extent.

    Advanced settings for multiple products

  7. Accept all the other default values and click OK.

    The Advanced Products Settings dialog box closes, and you return to the Product Generation Settings pane in the Reality Mapping Products wizard.

  8. Click Next to go to the DSM Settings pane, and ensure that the parameter values match the following:

    • Output Type—Mosaic

    • Resampling—Bilinear

  9. Click Next to go to the True Ortho Settings pane, and ensure that the parameter values match the following:

    • Output Type—Mosaic

    • Resampling—Bilinear

  10. Click Next to go to the DSM Mesh Settings pane, and ensure that the parameter values match the following:

    • Format—SLPK

  11. Click Finish to start the product generation process.

    Once product generation is complete, the DSM and true ortho products are automatically added to the 2D map view. In the Catalog pane, in the Reality Mapping container, DSM is added to the DEM folder, the DSM mesh products are added to the Meshes folder, and the true ortho products are added to the Ortho folder.

You have completed the generation of 2D products including a DSM, true ortho and DSM mesh using the Multiple Products wizard. You can also generate these 2D products using wizards for each specific product, as described below.

Generate a DSM

To generate a DSM using the Reality Mapping Products wizard, complete the steps below.

Note:

Elevation values can be derived when the image collection has a good amount of overlap to form the stereo pairs. Typical image overlap necessary to produce point clouds is 80 percent forward overlap along a flight line and 60 percent overlap between flight lines.

  1. On the Reality Mapping tab, click the DSM button DSM product in the Product group.

    The Reality Mapping Products Wizard window appears.

  2. Click Shared Advanced Settings.

    The Advanced Product Settings dialog box appears, where you can define parameters that will impact the Reality mapping products to be generated. For details of the advanced product settings, see Shared Advanced Settings in the wizard.

    The Quality value is automatically set and should not be changed to ensure optimum performance and product quality. However, if you want to generate a reduced resolution product, the Quality value can be lowered. See Shared Advanced Settings for more information about the impact of various quality settings on product generation.

  3. Accept the Pixel Size default values to generate products at source image resolution.

  4. For Product Boundary, select a feature class identifying the output product extent from the drop-down list, or click the Browse button Browse, browse to the file geodatabase in the tutorial data location, select Project_bdry, and click OK.

    It is recommended that you provide a product boundary for the following reasons:

    • Define the proper output extent—When you do not define a product boundary, the application automatically defines an extent based on various dataset parameters that may not match the project extent.

    • Reduce processing time—If the required product extent is smaller than the image collection extent, defining a product boundary reduces the processing duration and automatically clips the output to the boundary extent.

  5. Accept all the other default values and click OK.

    The Advanced Products Settings dialog box closes and you return to the Products Generation Settings pane in the Reality Mapping Products wizard.

  6. Click Next to go to the DSM Settings pane, and ensure that the parameter values match the following;

    • Output Type—Mosaic

    • Resampling—Bilinear

  7. Click Finish to start the product generation process.

    Once processing is complete, the DSM product is added to the Contents pane, the Data Products category, and the 2D map view. It is also added to the Catalog pane, the Reality Mapping container, and the DEMs folder.

    Generated DSM

Generate a true ortho

One of the options in the Reality mapping Product group is True Ortho. A true ortho is an orthorectified image with no perspective distortion so that above-ground features do not lean and obscure other features. To create a true ortho, a DSM derived from the adjusted block of overlapping images is required. As a result, a DSM will be generated as a part of the true ortho process regardless of whether a DSM was previously selected as a product. The generated true ortho image will be stored in the Orthos folder under the Reality Mapping category in the Catalog pane.

To generate a true ortho using the Reality Mapping Products wizard, complete the following steps:

  1. On the Reality Mapping tab, click the True Ortho button True ortho product in the Product group.

    The Reality Mapping Products Wizard window appears.

  2. Click Shared Advanced Settings.

    The Advanced Product Settings dialog box appears, where you can define parameters that will impact the Reality mapping products that you generate. For a detailed description of the advanced product settings, see Shared Advanced Settings in the wizard.

  3. Complete steps 3 through 5 in the Generate DSM section above.

  4. Click Next to go to the True Ortho Settings pane, and ensure that the parameter values match the following:

    • Output Type—Mosaic

    • Resampling—Bilinear

  5. Click Finish to start the product generation process.

    Once processing is complete, the True Ortho product is added to the Contents pane, the Data Products category, and the 2D map view. It is also added to the Catalog pane, the Reality Mapping container, and the Ortho folder.

    Generated True Ortho

Generate a DSM mesh

A DSM mesh is a 2.5D textured model of the project area where the adjusted images are draped on a triangulated irregular network (TIN) version of the DSM extracted from the overlapping images in the adjusted block. The Reality Mapping Products wizard simplifies the creation of the DSM mesh product by providing a streamlined workflow with preconfigured parameters. To create a DSM mesh product, a DSM derived from the adjusted block of overlapping images is required. As a result, a DSM is generated as a part of the DSM mesh generation process whether a DSM was selected as a separate product.

To generate a DSM mesh using Reality Mapping Products wizard, complete the following steps:

  1. On the Reality Mapping tab, click the DSM Mesh button DSM Mesh product in the Product group.

    The Reality Mapping Products Wizard window appears.

  2. Click Shared Advanced Settings.

    The Advanced Product Settings dialog box appears, where you can define parameters that will impact the Reality mapping products that you generate. For a detailed description of the advanced product settings, see Shared Advanced Settings in the wizard.

  3. Complete steps 3 through 5 in the Generate a DSM section above.

  4. Click Next to go to the DSM Mesh Settings pane, and ensure that the parameter values match the following:

    • Format—SLPK

  5. Click Finish to start the product generation process.

    Once processing is complete, the DSM mesh product is added to the Catalog pane, the Reality Mapping container, and the Meshes folder.

  6. To visualize the generated DSM mesh product, right-click the 3D_Mesh.slpk file in the Meshes folder, and from the drop-down menu, click Add to New > Local Scene.

    Generated DSM Mesh product

Summary

In this tutorial, you connected to Reality Server and created a Reality mapping workspace for drone imagery and used tools on the Reality Mapping tab to apply a photogrammetric adjustment with ground control points. You then used tools in the Products group to generate DSM, true ortho, and DSM mesh products.

The imagery used in this tutorial was acquired and provided by Esri, Inc.

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