Bundle block adjust aerial images

Author a mosaic dataset

The first step to bundle block adjust your aerial imagery is to create a mosaic dataset and load your aerial data into it.

1. Prepare a camera table and a frame table for your data.
   1. Create text files for the camera table and frame table, with all the necessary fields.

   The units for perspectiveX, perspectiveY, and perspectiveZ, in the frame camera table, should be the same units as the spatial reference of the mosaic dataset that you will create.

2. Use the Create Mosaic Dataset tool to create an empty mosaic dataset container.
3. Open the Add Rasters to Mosaic Dataset tool.
4. Choose Frame Camera for Raster Type.
5. Click the Raster Type Properties button to open, view, and edit the properties for the raster type.
6. Click the Properties tab.
7. Set the appropriate Orthorectification using elevation option. The elevation source can be an average elevation if the study area is small and flat, or an elevation raster dataset.
8. Click OK on the Raster Type Properties dialog box to accept the edits and return to the Add Rasters to Mosaic Dataset tool.
9. The Input Data is the frame table.
10. If the images within your mosaic dataset do not have pyramids, check the Build Raster Pyramids check box in the Raster Processing section.
11. Click the Environments button on the bottom of the tool to open the Environment Settings window.
12. Expand the Parallel Processing section and type 100% to leverage all the cores on your machine.
13. Click OK to accept the settings and close the window.
14. Click OK to run the tool.

This tool may take a long time to complete if you have a large number of images. Once the tool has finished, it automatically appears in your display.

Note:

If there are many black borders in your output mosaic dataset, you need to run the Build Footprints tool on your mosaic dataset using the Geometry computation method. You are now ready to create and refine your control points.

Prepare control points

The first step to bundle block adjust your aerial imagery is to create and prepare the control points for your aerial mosaic dataset.

1. Open the Block Adjustment window.
2. Use the Layer list to choose the mosaic dataset that you have just created.

   When you run the block adjustment operations from the Block Adjustment window, you have the advantage of having default naming conventions defined for your outputs. These default names will also be recognized by the Block Adjustment window when specific inputs are needed within the block adjustment workflow. For more information about the output tables, see Schemas of block adjustment tables.

3. Click the Block Adjustment Tools list and choose the Compute Tie Points tool, and choose the appropriate Image Location Accuracy for your images.
4. Optionally, if you have high-accuracy ground control points (GCP) available, add these into the Block Adjustment window using the Load GCP button .

Compute block adjustment

The third step is to compute the block adjustment. When you are satisfied with the computation, you will then apply the adjustment to the mosaic dataset.

1. Run the Compute Block Adjustment tool using the Frame method.
2. Run the Analyze Control Points tool to generate the coverage and overlap tables.

   If you open the tool from the Block Adjustment window, you will need to click the Reset button within the Block Adjustment window.

3. Examine the root mean square (RMS) and residual of the bundle block adjustment.
   • If there are specific residuals that are high, you should remove or edit those control points using the Block Adjustment window.
   • If there are areas that do not have any control points, you should add control points using the Block Adjustment window.
4. After you make any edits to the control points, recompute the adjustment using the Compute Block Adjustment tool.
5. Once the RMS is acceptable, use the Apply Block Adjustment tool on the mosaic dataset.

Orthorectify the mosaic dataset with a newly generated DTM

The accuracy of the aerial adjustment can be improved by generating high-resolution elevation data, and then applying it to the mosaic dataset.

1. Use the Build Stereo Model tool to build a stereo table of the mosaic dataset.

   Image pairs with a very small overlap area, a very small intersection angle, or a very large intersection angle should be eliminated while you run the Build Stereo Model tool.

2. Use the Generate Point Cloud tool to generate point cloud data as a folder of LAS files.
   • If your study has less terrain variation, or if you want a quick digital terrain model (DTM) generation, use the ETM (extended terrain matching) method.
   • If your study area has a lot of terrain variation or is an urban area, use the SGM (semiglobal matching) method to generate your DTM or digital surface model (DSM).

   If you want specific pairs to be used in the orthorectification process, open the Stereo table, and set a higher value for those pairs for the Use field. To open the Stereo table, right-click the mosaic layer in the table of contents, point to Open, and click Stereo.

3. Use the Interpolate From Point Cloud tool, using the DTM option to generate a DTM from the folder of LAS files.
4. Use the Apply Block Adjustment tool.
   1. Set the Input solution table using the solution table from the Compute Block Adjustment tool.
   2. Set the Input DEM using the DTM from the Interpolate From Point Cloudtool.