Manage tie points in an ortho mapping workspace

Available with Advanced license.

This workflow describes how to inspect images and edit tie points in your ortho mapping workspace.

Tie points are common objects or locations within the overlap areas between adjacent images. These points are used to improve geometric accuracy in the block adjustment. Tie points are usually computed automatically using image matching techniques. For certain cases, however, such as images that contain large bodies of water or sand, or images captured in different seasons, the automatic matching technique may not detect a sufficient number of points required for the adjustment. To address this, the Manage Tie Points pane provides tools to manually add and edit tie points.

This workflow details how to inspect images in a collection to review adjustment statistics, assess tie point coverage, activate and delete images, and edit tie points and point sets. You can filter images using the current display extent or image attribute queries, such as tie point coverage or adjustment root mean square (RMS) error.

Filter images using the Image Inspector pane

You can access the Image Inspector pane in the Review group under the Ortho Mapping tab. You can use the pane at any point in the ortho mapping workflow; however, you must perform a block adjustment before tie point and adjustment statistics are available for each image.

1. From the Manage Tie Points menu, click the Analyze Tie Points tool to generate tie point counts and coverage for each image in the collection.
2. Click the Attributes tool and filter the list of images by adjusting the ranges for RMS, tie point coverage, and tie point count.

   You can also filter images using the Extent tool to capture points within the current display.

3. Inspect individual images by selecting an image in the list.

   The image appears in the Preview window next to the image list, where you can view image information, including adjustment statistics, exterior orientation, and interior orientation.

   Some images may be dropped during the adjustment.

4. Click the Attributes tool and select Inactive from the drop-down menu to filter dropped images. Click the Activate or Delete buttons to add or remove an image from the adjustment.
5. Once you have identified images or point sets that you want to edit, select an image and click the Edit Tie Points tool from the Image Inspector pane to begin editing tie points for the current image.

The Image Inspector pane displays the filter by attributes tool.

Filter tie points using the Tie Point Editor tool

The Tie Point Editor tool is useful for reviewing individual point sets to assess how well tie points captured the same feature in each image.

1. Zoom to an area of interest in the image collection and turn on the tie point layer.

   Tip:

   Turn on the solution points layer. If there are any tie points that are not associated with a solution point, they may need to be reviewed.

2. Click the Tie Point Editor tool.
3. Click the Filter point sets tool to filter tie points according to current selection, extent, image ID, point ID, or attributes.

   For example, check the Attributes filter and adjust the Residual slider to filter tie points with high residuals.

Edit tie points

You can add, delete, or move tie points using the Tie Point Editor tool, located under the Manage Tie Points menu in the Refine group or launched from the Image Inspector.

Note:

If you launch the Tie Point Editor tool from the Image Inspector pane, tie points appear according to the filter settings specified in the Image Inspector pane.

1. Select individual point sets using the Point set drop-down menu.
2. Click the Add button to edit tie points within the current point set. Click and drag a tie point to move it.

   If you have added an image to the preview window, use the Add button to add a tie point to the current point set.

Note:

If image geolocation accuracy is low, overlapping images may not be displayed in the correct locations. Click the Load Images button and select the images that contain overlap. The images appear in the preview window. Images can also be added using the Add Images by Image Ids button .

Add or delete a point set

To add or delete a point set, complete the following steps:

1. To create a point set, click the Add a point set button , click the Load Images button , and draw a rectangle in the map to load the selected images to the preview windows.

   You can add tie points manually by clicking the matching feature in each image displayed in the preview windows. You can also add points using a semiautomated process.

2. Click Add a point set, click the Auto Add button , and select a feature in one image.

   The same feature is automatically detected in the remaining images.

3. Use the Delete current point set button to remove the selected point set. Click the Select filtered point sets on map button to select all tie points within the filtered list.

   The filtered tie points will be highlighted in the map display.

4. Click the Delete all filtered point sets button to delete all sets within the filtered list.

The Tie Point Editor pane displays quality information for a point set, along with the matching tie point location within each overlapping image.

Run the Adjust tool again to incorporate updated tie points in the adjustment. The updated results are displayed in the Image Inspector and Tie Point Editor windows.

Add tie points to include dropped images

In some cases, an image is dropped during block adjustment due to insufficient tie point coverage. This occurs when neighboring images do not meet minimum overlap requirements or when much of the image is covered by clouds or water. You can reactive dropped images and include them in the block adjustment by adding tie points manually.

1. Select the Image Inspector tool in the Ortho Mapping tab.
2. Click the Attributes tool and select Inactive from the drop-down menu to filter dropped images. Click the Activate button to add dropped images to the adjustment.
3. Click the Edit Tie Points tool from the Image Inspector pane to begin adding tie points for selected images.
4. Click the Add button and manually add at least five tie points to each dropped image.

   The added points cover matching features in at least two adjusted, overlapping images.

Points should cover one ninth of the image area as a best practice.
5. Click Adjust.

   The dropped images are now included in the adjusted image collection.