Resolving calibration mismatch errors during Aura colorization

This article covers how to address processing failures caused by a mismatch between the camera used during capture and the calibration file provided in the scan data.

Error Message

Processing Failed:

Camera serial number of video and calibration files for Hovermap do not match. Please check you have selected the correct datasets and data was captured with a calibrated Hovermap and camera.

 

Why does this occur?

This error occurs when Aura detects that the camera serial number embedded in the video file does not match the serial number in the associated calibration file (col_st_XXXX.yaml).

Accurate colorization requires that the Hovermap, camera, and mount are calibrated together as a matched set. The calibration process generates a file (e.g., col_st_XXXX.yaml) that captures the precise spatial relationship between these components, including the camera’s position and orientation relative to the Hovermap, as well as lens and alignment parameters. Aura uses this file during processing to correctly project video frames onto the 3D point cloud.

Because calibration is unique to each Hovermap–camera–mount combination, using different hardware or an incorrect calibration file can lead to poor color quality or misaligned results. Always use the original calibrated hardware and ensure the correct calibration file is present when processing scans.

 

Cause: The incorrect Go Pro was used during capture

When multiple Hovermaps or cameras are present on-site, equipment may be inadvertently mismatched. For clients operating several colorized Hovermap units, a common cause of this error is that the scan was captured using a camera that was not calibrated with the corresponding Hovermap.

 

Resolution

To resolve this issue, begin by confirming whether the camera and Hovermap were correctly paired. This requires comparing the serial number stored in the scan’s calibration file with the serial number on the physical camera. If they match, the pairing is correct. If they do not, the wrong camera was likely used during capture.

• Verify the pairing – Check the serial numbers in both the scan data and on the physical camera.

• Fix the pairing – If there’s a mismatch, locate the correctly paired camera and reprocess the scan.

• Recover if needed – If the correct pairing is not available, consider the alternative processing options described below to potentially recover the data.

 

Step 1: Locate the calibrated GoPro serial number in the scan data

1. Open the scan folder associated with the failed processing attempt.

2. Locate the file named col_st_XXXX.yaml

3. Open this file in a text editor. (Notepad is sufficient, but a code editor such as VS Code offers better readability.)

4. Search for the entry sn:

5. Record the camera serial number listed next to sn:

Step 2: Locate the physical GoPro’s serial number

The only supported camera for colorization is currently a GoPro.

1. Open the GoPro’s battery compartment and locate the serial number sticker.

2. Alternatively, the serial number can be found:

   • In the on-screen menu under Preferences > About > Camera Info

   • On the original packaging or camera case

   • In the GoPro Quik app, if the camera is paired

Step 3: Compare and validate serial number pairing

1. Compare the serial number from Step 1 (col_cal.yaml) with the physical camera’s serial number from Step 2.

2. If the numbers match, the Hovermap and camera are correctly paired.

3. If they do not match, locate the camera that matches the calibration.

 

Can I still process this data?

The data was captured using a Hovermap and camera that were not calibrated together. While this is not ideal, there are two available workarounds. However, neither method guarantees a successful result, and colorization quality may be reduced.

Option 1: Obtain a new calibration file

It is possible to perform a post-scan calibration that matches the hardware used during the original capture. This allows the scan to be processed even if the original calibration was missing, incorrect, or mismatched.

A new calibration file will be generated and can be manually copied into previously offloaded scans to potentially enable successful colorization.

For assistance, please contact your regional Emesent partner or the Emesent Client Support team.

 

Option 2: Bypass the serial number check

You can bypass the serial number validation by replacing the col_st_XXXX.yaml file in the scan folder with a calibration file from a scan where the camera was correctly calibrated.

Step 1: Locate the calibration file for the camera

1. Find a scan captured with the Hovermap the camera is calibrated to.

2. Open the scan folder for that dataset.

3. Locate the file named col_st_XXXX.yaml.

4. Copy this calibration file for use in the failed scan.

Step 2: Replace and reprocess

1. Open the scan folder for the dataset that failed to process.

2. Replace the existing col_st_XXXX.yaml file with the copied calibration file.

3. Reprocess the scan in Aura using the updated file.

 

Related Documentation and Support

For further guidance, see:

• Working with Colorization

If you are unsure or need assistance, please Emesent Client Support team or reach out to the Emesent Client Support team.