FAQs

How do I determine which GNSS (APX-15, .T04) files go with each flight?

1. GNSS data is split into folders by year, month, and day.

2. If multiple flights are conducted back to back, there are a few methods of determining which files go with various datasets:

   1. New files are generated every third minute (UTC timestamp). Often, there will be a time jump between the last file of one flight and the first file of the next flight that is longer than three minutes. In this case, different flights can be determined easily by the timestamp cutoffs.

   2. Downloading T04 files after each flight and adding them to a labeled folder can help keep track of which mission these files belong to.

   3. After downloading VNIR or SWIR data, you can open the imu_gps.txt file and investigate the timestamp column. Times in this file and on the T04 are in UTC, so you can get a clearer picture of when hyperspectral started recording and line that up with the T04 timestamps.

   4. If you're very efficient in the field, the three minute gap between T04 files may not have enough granularity to determine when one dataset ends and another begins. The amount of time per file can be configured on the Data Logging page. Some users set this to one minute so the gaps are more obvious, but as described above, there are plenty of methods to keep files straight without modifying this parameter.

LiDAR did not record

Check that the ethernet cable is connected to the VNIR port and has been fully seated in the connector.

GNSS data did not record

Ensure logging is enabled by default

Check that antenna connection is fully tightened and correct antenna has been used

Check that drive space is not full

Dark Reference for SWIR did not take long enough

Occasionally dark reference will fail to collect. Check the File Manager and look at the size of the dark reference folder. It should be ~ 360mb. If it is off by more than 10-20mb, repeat dark reference.

Dark Reference for SWIR is taking too long

Occasionally dark reference will fail to collect. Stop the dark collection, then restart it. This should resolve the issue.

Stripes and peaks in SWIR raw data cubes

The image striping and random peaks in the plots are from hot or weak pixels due to sensor non-uniformity. This is nominal, expected behavior for SWIR spectrometers.

Once the data is converted to radiance and reflectance these stripes and peaks will mostly be eliminated.