Block adjustment

Available with Advanced license.

When an ortho mapping workspace is created, the next step is to perform block adjustment using the tools in the Adjust and Refine groups. The adjustment tools encapsulate operations of computing match points (tie points) from overlapped images, performing triangulation calculations, and coarse orthorectification. The adjustment tools use an algorithm and processing procedure that are suitable for each ortho mapping workspace type. For instance, the algorithm performs RPC triangulation for satellite images and frame triangulation for aerial images. The parameters used in the adjustment computation can be defined on the Adjust dialog box. The adjustment quality report can be viewed using the Quality Report tool.

Note:

Aerial triangulation within an ortho mapping project in ArcGIS Pro has the following limits:

• 100 gigapixels (GP) for drone and digital frame imagery
• 1000 GP for scanned aerial imagery
• No limit on the size for satellite imagery

The project size in gigapixels can be calculated by multiplying the number of images by image megapixel size and dividing by 1000.

For example, if an aerial image is 10,000 x 12,000 pixels, the image is 120 megapixels.

A project with 400 120-megapixel images is (400 x 120)/1000 = 48 gigapixels.

These limits represent the expected limit in the size of blocks that can be effectively handled. Larger blocks may work in the current version of ArcGIS Pro, but limits may be further enforced in future releases. The limits are not placed on ortho mapping running as part of ArcGIS Image Server on appropriate hardware.

Adjust tool

The Adjust tool is used to perform block adjustment of the image collection in the current ortho mapping workspace. The processing can be done at image source resolution—computing tie points from source images, then performing triangulation using the computed tie points, or at a coarse resolution to estimate exterior image orientations and improve GPS location. Drone and scanned aerial images typically include poor quality or no exterior orientations and coarse GPS information. If orientation information is contained in the metadata for drone imagery, check the Use Orientations from Metadata check box. Otherwise, the orientation parameters omega, phi, and kappa is computed. In most cases, an initial adjustment is performed at a coarse resolution—a user-defined pyramids level is used to estimate the image orientations, then an adjustment is performed at the source resolution. The tie points generated at the initial adjustment is used to seed the tie point computation and triangulation calculation at the source resolution in the refined Adjust calculation. Having pyramids built for the image collection in advance or during ortho mapping workspace creation shortens the initial adjustment process.

Adjustment options

The parameters used to compute the block adjustment are defined on the Adjust dialog box . These include transformation type, tie point density, relative accuracy of source imagery, computed adjustment points, and other parameters as described below. The appropriate set of parameters is presented on the dialog box depending on the type of workspace specified. For example, the parameters presented for a satellite imagery workspace differ from those specific to drone imagery.

Reset tool

The Reset tool returns the workspace to the previous selected state. This allows you to change adjustment parameters, reprocess the image collection, and refine your results. Use the Reset to Initial option to return the workspace to the initial, unadjusted state. Use the Reset to Estimated option to return the workspace to the quick adjusted state, or the Reset to Full Adusted option to reset the workspace to the previous full adjustment. To preserve the current ortho products, save a copy before running reset.

Refine adjustment

To further improve the adjustment accuracy with ground reference, you can add ground control points (GCP) using the Manage GCP tools in the Refine group. The adjustment quality can be viewed from an adjustment report using the Adjustment Report tool. To view adjustment information for individual images, including tie point coverage, tie point count, and the root mean square (RMS), use the Image Inspector in the Review group. This allows you to filter or delete images based on the adjustment statistics or to activate images that were not used in the adjustment. If the adjustment errors are larger than expected, use the Manage Tie Points tools to check your tie points.

Layer rendering

Once you have performed an adjustment, the Solution Data and Control Points layers will be populated in the Contents pane. To adjust layer symbology, right-click the layer, select the layer symbology, and choose a method for displaying the associated points. Layer groups can also be turned on and off.

Manage Tie Points

The Manage Tie Points pane is used to view and edit tie points and point sets for selected images. Run the Analyze Tie Points tool to generate a coverage feature class and an overlap polygon feature class, which are added under the QA/QC Data entity and included in the Image Inspector table. The two feature classes help you understand whether you have enough tie points and where you need to add more tie points. Use the Tie Point Editor to filter, add, and remove tie points or point sets in individual images. To add tie points for specific areas within your image collection, or recompute tie points using different parameters, run the Recompute Tie Points tool .

These tools update the control points in the ortho mapping workspace. Run the Adjust tool again to incorporate changes and update the image collection. For the full workflow using the Tie Point Editor and Image Inspector, see Manage tie points in an ortho mapping workspace.

Icon	Name	Description
	Load Images	Select and load overlapping images from the map.
	Add images	Add overlapping images.
	Add Images by ID	Add images by image ID.
	Remove images	Remove images.
	Add a point set	Create a point set from the selected tie points.
	Add a tie point	Create a tie point by clicking a location in an image in the Preview pane. Then add the corresponding tie points in the other images.
	Delete all filtered point sets	Delete all listed point sets.
	Delete point set	Delete the selected point set.
	Delete tie point	Delete the selected tie point.
	Undo the last edit of the tie point	Undo the last edit of the tie point.
	Dynamic Range Adjustment	Adjust the stretch using only the data contained within the image display window.
	Center to tie point	Center the viewer to the tie point.
	Filter point sets	Filter point sets by selection, current map extent, and attributes.
	Flash tie points in the point set on map	Highlight the selected point set on the map.
	Select filtered point sets on map	Highlight the filtered point set on the map.
	Show solution point	Show the solution point in viewers.
	Synchronized zoom in	Adjust all image views to the scale of the first image.
	Synchronized zoom out	Zoom out to a fixed scale for all images in the preview.
	Zoom	Zoom to the full image extent.

GCP Manager

The GCP Manager pane is used to add, edit, and manage your control points so they can be used in your ortho mapping project. If your GCP Manager does not have any rows in the table, it means that there are currently no GCPs or tie points associated with your ortho mapping project. If you already have GCPs saved in a file, you can import them using the Import GCPs button . If you do not have a GCP file, you can create GCPs using Compute GCPs , which is under the Manage GCPs drop-down menu. You can also create GCPs and tie points using the Add GCP or Tie Point tool .

GCPs can be added manually to the GCP Manager by using the Add GCP Manually button . Once selected, a new row will be added to the GCP Manager table. The GCP ID, X, Y, and Z fields can be edited or updated with the respective coordinate information. The XY Accuracy or Z Accuracy field can be used to classify a GCP as a 1D, 2D, or 3D point. Use the following as a guide when reclassifying a GCP.

• One dimensional (1D) GCP—A GCP having only a vertical or Z value. The XY Accuracy field for this GCP type must be set to NA and have only a height or Z value entered in the Z field.
• Two dimensional (2D) GCP—A GCP having X and Y values (easting and northing) only. The Z Accuracy field for this GCP type must be set to NA, and have X and Y values entered in the appropriate fields.
• Three dimensional (3D) GCP—A GCP having a X, Y, and Z values (easting, northing, and height).

  Note:

  Double-click in each field to enter 3D values in the GCP Manager. A 3D GCP can be converted to a 1D or 2D GCP by setting the XY Accuracy or Z Accuracy fields to NA.

GCP Manager with 1D, 2D, and 3D GCPs is shown.

Once 2D or 3D GCP coordinates are entered in the GCP Manager table using the Add GCP’s Manually button , a pending GCP symbol will be displayed in the 2D map view highlighting the GCP location. The accuracy of the displayed GCP location will be directly related to the accuracy of the map. It is recommended that a surveyor-supplied description or image showing the GCP location be used to guide point identification and measurement. 1D GCPs that do not have X and Y values will not be displayed on the map.

The table below lists all the tools you can use within the GCP Manager pane. For the full workflow to add GCPs, see Add GCPs to your ortho mapping workspace.

Icon	Name	Description
	Add GCP or Tie Point	Create a GCP by clicking a location on the map. Then add the corresponding tie points in the GCP Manager viewer.
	Add GCP Manually	Creates an empty row with a generic GCP ID for adding 1D, 2D, or 3D GCPs to a project. The corresponding GCP tie points can be measured in the GCP Manager preview window.
	Clear Links	Delete all the links between the images, for the selected ground control point.
	Delete GCP	Delete the selected ground control point.
	Undo deleted GCP	Undo the Delete GCP operation.
	Delete All	Delete all the ground control points.
	Import GCPs	Import a GCP file from a text file, a CSV file, or a feature class. The feature class must have x,y defined in either the Shape field or in two separate fields.
	Export GCPs	Export the GCPs to a file.
	Filter	Switch the filter toggle button to show all the GCPs, or only the GCPs in the current map display. The default is to show all GCPs. Click the Filter button to filter out GCPs that are outside of the current extent. This can be used when GCPs are outside of the area of the image collection, or used to focus on one GCP within the area of interest.
	Refresh	Refresh the GCPs in the GCP Manager and the map display. This is useful when you make an edit to a GCP, to make sure that the manager and the map display are still in sync.
	GCP_Manager	Supports defining the GCP value format and setting the type, color, and size of the symbol used for the measured GCP tie point.
	Define Z Correction	Defines the Z correction method for manually collecting ground control points when the transformation cannot be defined using the Map property.
	Set GCP Accuracy	Update GCP accuracy value for all or selected GCPs.
	Add images	Add selected images to the preview window.
	Add images by ID	Add images to the preview window using the image ID.
	Zoom	Zoom to the full extent of the image.
	Show GCP	Display the corresponding GCP location in the image display window.
	Dynamic Range Adjustment	Adjust the stretch using only the data contained within the image display window.
	Stretch	Applies a percent clip stretch and with a modified Max cutoff default value.
	Sharpen	Applies a convolution filter to the preview image.

To temporarily disable a GCP, change the XY Accuracy and Z Accuracyfields to <NA>.

To change a GCP into a check point, right-click the GCP row in the table, and choose Change to Check Point.