Perform a Reality mapping block adjustment

Available with Standard or Advanced license.

Available for an ArcGIS organization with the ArcGIS Reality license.

When a Reality mapping workspace is created, the next step is to perform a block adjustment using the tools in the Adjust and Refine groups. The adjustment tools compute match points (tie points) from overlapped images and perform triangulation calculations and coarse orthorectification. The adjustment tools use algorithms and processing procedures suitable for each Reality mapping workspace type. You can define the options that are used in the adjustment computation in the Adjust dialog box. You can review the adjustment report in the Adjustment Report window.

Adjust tool

The Adjust tool is used to perform a block adjustment of the image collection in the current Reality mapping workspace. The processing can be done at image source resolution—computing tie points from source images and performing triangulation using the computed tie points, or at a coarse resolution to estimate exterior image orientations and improve GPS location. For example, drone images may have poor-quality or no exterior orientations and coarse GPS information. In this case, an initial adjustment can be performed at a coarse resolution: a user-defined pyramid level is used to estimate the image orientations, and an adjustment is then performed at the source resolution. The tie points generated at the initial adjustment are used to seed the tie point computation and triangulation calculation at the source resolution in the refined calculation performed by the Adjust tool. Building pyramids for the image collection ahead of time or when creating the Reality mapping workspace reduces the time of the initial adjustment process.

Adjustment options

The options on the Adjust dialog box define the block adjustment computation. They include tie point density, relative accuracy of source imagery, computed adjustment points, and other options described below. The applicable set of options available on the dialog box depends on the type of workspace specified. For example, the options for a drone imagery workspace differ from those for aerial digital imagery.

Reset tool

The Reset tool returns the workspace to the previous selected state. This allows you to change the adjustment values, reprocess the image collection, and refine the 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 Adjusted option to reset the workspace to the previous full adjustment. Prior to resetting the adjustment, save a copy of the workspace to preserve any generated products.

Save a copy of the workspace

To save a copy of the workspace, complete the following steps:

1. In the Catalog pane, expand the Reality Mapping workspace container.

   

2. Right-click the workspace to be copied and click Copy from the drop-down list.
3. Right-click the Reality Mapping workspace container and click Paste.

   The Reset functionality is not enabled by default, and can be activated by checking the box next to Allow adjustment reset, on the Workspace Configuration page of the Workspace Creation wizard.

Refine the adjustment

To improve the adjustment accuracy with ground reference, you can add ground control points (GCPs) using the Manage GCP tools in the Refine group.

The adjustment quality can be assessed by reviewing the GCP residuals in the GCP Manager table. GCP residual information is listed in the dX, dY, and dZ fields, which represent deviations of the measured positions from their true ground coordinates in x, y, and z directions, respectively. Residuals can be sorted in ascending or descending order by clicking the field title. GCPs with higher-than-expected residual values typically indicate an error in the surveyed ground coordinate, the recorded coordinate, or the measured image position. If you encounter GCP measured positions with high residual values, it is recommended that you review, remeasure, and rerun the adjustment to incorporate any changes. If no improvement in the residual values is observed, right-click the GCP label and click Check Point to change the point status. Similar to GCPs, check points are points with known ground coordinates and capture features that are visible in multiple overlapping images. However, they are not used as inputs to control the adjustment process. Instead, check points measure the accuracy of the adjustment results. For each check point, the distance between its known ground location and the location of the corresponding pixel after the adjustment process is used to calculate the root mean square error (RMSE). The adjustment must be rerun after changing the point status to incorporate the change in the adjustment process. Additional statistical information related to block adjustment accuracy is available in the Adjustment Report window.

Note:

To further refine adjustment accuracy, you can add or remove GCPs, and rerun the adjustment.

To view adjustment information for individual images, including tie point coverage, tie point count, and the root mean square (RMS), use the Image Inspector pane 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 the tie points.

Adjust layer symbology

Once you have performed an adjustment, the Solution Data and Control Points layers are 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

Use the Manage Tie Points pane 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 can help you understand whether you have enough tie points and where you need to add more tie points. Use the Tie Point Editor tool to filter, add, and remove tie points or point sets in individual images. To add tie points to specific areas in your image collection or recompute tie points using different parameters, run the Recompute Tie Points tool .

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

The adjustment tools are described below.

Button		Description
Filter point sets		Filter point sets by selection, current map extent, and attributes.
Delete filtered point sets		Delete all listed point sets.
Select filtered point sets on map		Highlight the filtered point set on the map.
Add a point set		Create a point set from the selected tie points.
Delete current point set		Delete the selected point set.
Flash tie points in the point set on Map		Highlight the selected point set on the map.
Previous point set		Use previous point set.
Next point set		Use next point set.
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 Image		Remove images.
Auto Add		Add a tie point, and use auto-matching to match the remaining tie points comprising the model.
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 Tie Point		Delete the selected tie point.
Undo		Undo the last edit of the tie point.
Center To Tie Point		Center the view to the tie point.
Zoom		Zoom to full image.
Synchronized Scale		Synchronize all images in the preview with the same scale of the first image.
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.
Synchronized Pan		Pan all images in the preview.
DRA		Use dynamic range adjustment (DRA) to adjust the stretch using only the data contained within the image display window.
Show solution point		Show the solution point in the viewer.

GCP Manager

Use the GCP Manager pane to add, edit, and manage control points so they can be used in Reality mapping projects. If the GCP Manager pane does not have any rows in the table, it means that there are no GCPs or tie points currently associated with the Reality mapping project. If you 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 from the Manage GCPs drop-down menu. You can also create GCPs and tie points using the Add GCP or Tie Point button .

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.

• If adding a one-dimensional (1D) coordinate, enter the height value in the Z field and set the XY Accuracy field value to NA. Optionally, input the GCP Z Accuracy value.
• If entering a two-dimensional (2D) coordinate, add the X and Y coordinates to the appropriate fields and set the Z Accuracy field value to NA. Optionally, enter the GCP XY Accuracy value.
• If entering a three-dimensional (3D) coordinate, add the X, Y and Z coordinates to the appropriate fields. Optionally, set the GCP XY Accuracy and Z Accuracy values.

Note:

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

When 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's location. The accuracy of the displayed GCP location is 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 the tools in the GCP Manager pane. For the full workflow to add GCPs, see Add ground control points to a Reality mapping workspace.

Button		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 GCP.
Delete GCPs		Delete the selected GCP.
Undo Delete GCPs		Undo the Delete GCP operation.
Delete All		Delete all the GCPs.
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		Turn the filter toggle button on or off 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 to focus on one GCP within the area of interest.
Refresh		Refresh the GCPs in the GCP Manager pane and the map display. This is useful when you edit a GCP to ensure that the GCP Manager and the map display are still in sync.
GCP Manager Options		Define the GCP value format and set the type, color, and size of the symbol used for the measured GCP tie point.
Define Z Correction		Define the z correction method for manually collecting ground control points when the transformation cannot be defined using the Map property.
Set GCP Accuracy		Update the GCP accuracy value for all or selected GCPs.
Select Images		Add selected images to the preview window.
Add Image 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 in the image display window.
Stretch		Apply a percent clip stretch with a modified maximum cutoff default value.
Sharpen		Apply a sharpening convolution filter to the preview image.
View GCP Photo		View the associated photograph of the GCP location.

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

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