Initial Guess

Since the bundle adjustment algorithms use the current locations of the instruments as a starting guess, it is best to “rough” position the instruments. To do this, either enter the instrument transformations manually, or use the Drag Instruments function from the Instruments menu. It is best to place the instruments near their final location, as this will speed the bundle solution. If using theodolites with level compensators, you will use the option to force instrument vertical during the bundle adjustment. If this is the case, the virtual instru- ment models should be perfectly parallel to each other before initiat- ing the bundle adjustment.

Scale-Bar Database

For instruments that measure angles and distances, it is not necessary to use scale-bars in the bundle process. They are required for theodo- lite networks, however, because without them, the instruments will scale freely.

SpatialAnalyzer contains a scale-bar database. This is where you can enter the various scale-bars you have placed into the measurement area. Essentially what this database does is it associates target names with a scale-bar distance and uncertainty.

To modify the database, select the Scale-Bars tab from the User Op- tions page. The next window will list all of the current scale-bars and their information.

To add a scale-bar, press the Add button and a new record will be gen- erated. Complete the information required and press the Apply button.

You should see the information in the list window update.

Since an accurate bundle solution for theodolites requires at least one scale-bar, make sure this database is populated before attempting a bundle. In addition, make sure the targets for the end of the scale-bar have been shot and included in the list of targets to be included in the bundle solution.

Note, however, that you may populate the scale-bar database at any- time before attempting to bundle adjust. It is not necessary to have this database in place before taking measurements.

Select Bundle Adjust from the Instruments menu. Next, select the in- struments you wish to bundle using the dialog. The instruments that you select are the instruments that will be moved in order to refine the network solution. If you have 4 instruments, you will only have to bundle 3 because the first instrument may remain fixed while the others are adjusted relative to it. You may, however, select all of the in- struments. This will make the solution take longer, however, because the entire network will be allowed to float in space. Next, the Bundle Adjustment dialog will appear. This dialog will allow you to configure the settings for the bundle, run the optimization, and view the results.

Selecting Targets to Bundle

Once the Bundle Adjustment window appears, you may select the targets to be included in the bundle. SpatialAnalyzer will default to including ALL of the targets. You may reduce the number of targets for computational efficiency or target accuracy reasons.