Create an ortho mapping workspace for scanned aerial imagery

Available with Advanced license.

Computing the photogrammetric solution for an aerial image is determined by its exterior orientation (EO), which represents a transformation from the ground to the camera, and its interior orientation (IO), which represents a transformation from camera to image. For scanned images, the image interior orientations are also affected by the fiducials and how the aerial photographs are scanned. This data must be provided in tabular form.

The workflow for creating the interior and exterior orientation tables depends on the metadata that is available with your scanned images. For example, if you already have a description of the camera model and a table that describes the x,y,z location and the Omega, Phi, and Kappa orientation of each image file, you can use the Ortho Mapping Workspace wizard to create the required tables. The cameras table defines the camera model and IO, while the frames table defines the EO of the images. These tables can also be prepared before creating your workspace using the Build Frame and Camera Tables tool. The two tables can be provided in a .csv format or as ArcGIS supported tables. See Frames table schema and Cameras table schema for more information.

The type and quality of your metadata will determine characteristics of your ortho mapping workspace and the quality of your ortho mapping products. For example, if you do not provide fiducial information, you cannot refine the interior orientation. You can estimate fiducial information to produce a fiducial template used to refine your interior orientation and produce improved ortho mapping products. The processing capabilities supported by different levels of metadata information are summarized in the table below.

Note:

• Omega, Phi, and Kappa are required, but if these values are missing, you can enter a value of 0 (zero) in your frames table, and they will be estimated automatically.
• The film fiducial information can be estimated from the camera's film coordinates if a formal calibration report is not available.

Solutions for limited metadata

If you have more limited metadata, such as no estimate for perspective center (x, y, z) or limited information on the camera model, creation of the cameras and frames tables in an ArcGIS-supported format may require a more manual process.

If you have already georeferenced your scanned imagery, or you have a relatively small number of images to process, ortho mapping supports creation of a workspace from georeferenced imagery. You must provide information on the camera model in the camera table, such as focal length and pixel size. However, you can enter a value of 0 (zero) for the perspective points (x,y,z) and Omega, Phi, and Kappa in the frames table. These parameters will be automatically estimated when you create your scanned workspace.

Workflow data requirements

The scanned workflow for processing historical aerial imagery requires three types of data:

• Frames table—This must include image names, perspective center (x,y,z), and Omega, Phi, and Kappa in tabular form or an Esri frames table.
• Camera table—Information on the camera model must be provided in a cameras table. This includes parameters such as focal length, pixel size, principal point, lens distortion, and the fiducial film coordinates of the camera. This information can be found in the camera calibration report associated with your imagery.
• DEM—Provides an initial height reference for computing the block adjustment. World Elevation Services is used by default. For relatively flat terrain, you can specify a constant elevation or z-value.

Create an ortho mapping workspace

To create an ortho mapping workspace for scanned aerial imagery, complete the following steps:

1. On the Imagery tab, click New Workspace.
2. On the Workspace Configuration page, type a name for your workspace.
3. Use the Workspace Type drop-down arrow to choose Aerial - Scanned.
4. Click Next.
5. On the Image Collection page, specify the Exterior Orientation File / Esri Frames Table file. This table, in .csv format, enables specification of parameters that compute the exterior orientation (EO) of your imagery.

   If you input an Exterior Orientation file that is not an Esri Frames Table file, the Frames page will open for you to input field mapping information.

6. The Frame Spatial Reference parameter will be automatically set by the spatial reference of the perspective points defined in the Esri Frames Table. If the Frame Spatial Reference parameter is not specified, click the Spatial Reference button to set the spatial reference to be the same coordinate system as the perspective points.
7. Specify the Cameras table file. This is the .csv file that contains the camera configuration information.

   If you Add a camera , or Import a camera file that does not conform to the cameras table schema, the Add New Camera page will open for you to enter the camera information. The Calibration tab on the Add New Camera page is where you enter the camera information, usually available from the manufacturer.

   Use the Distortion tab to enter the camera distortion information, if available. This type of information is often available in the camera calibration report.

   Optionally, use the Export button on the Source Data Properties tab to store the camera calibration parameters as an Esri cameras table for future use.

8. Specify a Spatial Reference for your workspace, which applies to your image collection and ortho mapping products to be generated.
9. If the various inputs comprising your workspace have different coordinate systems, you can specify a common map projection system by clicking the Edit button . The Coordinate System Transformations dialog box appears and allows you to choose a coordinate system from the Select Transformation drop-down list and specify Geographic Transformations.
10. Optionally, click the Data Loader Options tab to further refine your output workspace.
    1. The ortho mapping workspace for aerial imagery requires elevation data to establish an estimate of flying height for each image. The DEM parameter wizard provides World Elevation Services by default. You can use a different DEM service or file by navigating to it. Choose your Elevation Source.
       • If you have access to the internet, use the default elevation service for the DEM parameter, and Average Elevation from DEM for the Elevation Source option.
       • If you do not have access to the internet, provide a DEM file covering the project area, and choose Average Elevation for the Elevation Source option.
       • If you do not have access to the internet or a DEM, choose the Constant Elevation option from the drop-down menu and enter an elevation value.
    2. Check the Estimate Statistics check box to estimate the statistics for your output workspace.
    3. Edit the Band Combination parameters, if you want to reorder the band combination from the default order.
    4. Choose either of the Pre-processing options to Calculate Statistics or Build Pyramids on your data before you create your workspace.
11. Click Finish to create the workspace.

When the ortho mapping workspace is created, the image collection will be loaded in the workspace and displayed on the map. You are now ready to perform adjustments and generate ortho products.

Scanned historical imagery tutorial

For a guided tutorial on the full scanned imagery workflow, see Create Scanned Aerial Imagery Products in ArcGIS Pro.