Merge scans in Aura

This article explains how to configure and run the Aura Merge workflow. For an overview of how merge works, scan compatibility, and troubleshooting, see Merge workflow overview.

What you will need

• Approximately 20% overlap between scans to support accurate alignment.

• Each scan processed individually in Aura before merging, according to its type.

• Sufficient available RAM. Avoid merging point cloud files that exceed available RAM, and use subsampled point clouds to reduce computational load.

Vehicle RTK, backpack RTK, and non-RTK scans can be merged together. RTK scans improve the alignment of non-RTK scans in areas where they overlap.

Each scan must be processed in Aura before merging according to its type. For per-type requirements, see Merge workflow overview.

Procedure

Step 1: Configure the merge job

1. Open Emesent Aura and click Process Scan in the top-left corner.

   

2. Select the Merge workflow in the Configure New Scan Job panel.

Select the offload folder containing the .bag files. Do not select the Output folder, as Aura will not detect the scan files.

3. Click Add Datasets, then click Add next to Add dataset folder.

4. When prompted, select the Scan Environment that most closely matches the scan.

   

4. Wait for Aura to detect and list the available files.

   

5. Repeat steps 3 to 5 for each additional scan to include in the merge.

Step 2: Choose an alignment base for preview

In the Alignment Preview File column, select any scan as the alignment base. It is used for preview only and does not affect the final output. Where available, Aura defaults to a subsampled version.

For RTK merges, select an RTK scan as the Alignment Preview File (satellite icon) to avoid unnecessary manual alignment.

Step 3: Configure overrides

Use Apply Overrides to configure scan-specific settings such as exclusion zones or trim data.

For RTK and RTK + non-RTK merges, verify that RTK scans have the correct georeferencing method and GNSS receiver type assigned. Aura applies these automatically.

Step 4: Select a reference scan (Optional)

If a reference scan is not selected, Aura performs pairwise alignment between all point clouds. This increases computational complexity and may extend processing time.

For non-georeferenced (non-RTK) merges, one scan can be set as the reference scan. The reference scan is locked in place, and all other scans align to it.

For RTK and RTK + non-RTK merges, reference scans are also supported. Proceed to Step 5.

Step 5: Configure processing settings

1. Define the location and name for the merged output.

   

2. Adjust the general merge and output options. See Merge settings for a full reference.

   

For RTK and RTK + non-RTK merges, also configure the following:

1. Set the Base Coordinate Reference System to match the original horizontal CRS used during scan acquisition (for example, EPSG:4326, WGS 84).

2. To manually enter a full PROJ string, enable Custom base CRS.

3. (Optional) Enable Reprojection to transform the output into a different coordinate system, then define the Target Coordinate Reference System by selecting the desired horizontal and vertical CRS values.

Step 6: Review and manually align

When georeferencing is unavailable or inconsistent across datasets, manual alignment provides an initial position estimate.

Manual alignment is required in the following scenarios:

• Merging scans without georeferencing (for example, non-RTK).

• Merging georeferenced and non-georeferenced scans together (for example, RTK + non-RTK).

For RTK-only merges with correct setup, Aura indicates that no manual alignment is required. Skip to Step 7.

Aura attempts to merge scans even if they are misaligned, either horizontally or vertically. This can result in a skewed or inaccurate final output. Always verify alignment before continuing.

1. Click Load Scans to load all selected point clouds into the viewer.

   • Each scan is assigned a unique color to assist with differentiation and alignment.

   • To add or remove datasets from the current merge job, click Edit Point Clouds Selected.

Align scans manually using the Translate and Rotate tools:

2. • Start in Top View to position and rotate scans horizontally.

   • Switch to Front View to adjust scans vertically.

Click Reload Scans in the Configure New Scan Job panel to reset a scan's position.

Step 7: Start the merge

1. Click Start to begin processing.

   

Start button not visible

If the Start button is hidden, click the Configure New Scan Job panel at the bottom of the window to reopen the Processing Scan panel.

Step 8: Combine the merged outputs

When the merge completes, the outputs are available in the Merge Complete panel. To combine and save them as a single point cloud, see Combine merged datasets.

For RTK merges, an accuracy report is also generated for each scan. To view a combined report across all outputs, see View the combined accuracy report.

Outcome

Aura outputs one .laz file per scan to the directory specified in Step 1, georeferenced where applicable. The outputs are grouped in the Merge Complete panel and are ready to combine.

Additional information

• Combine merged datasets: next step, inspect, validate, and save the output as a unified point cloud.

• View the combined accuracy report: generate a combined accuracy report (RTK merges only).

• Merge workflow overview: compatibility, troubleshooting, and how the workflow is structured.

• Merge settings: full reference for merge and output options.