Base GNSS data is necessary for the ROCK Desktop PPK workflow.
When processing LiDAR data in ROCK Desktop, you will need to provide Base GNSS data that was collected before, during, and after your survey. The accuracy of your Base GNSS data will influence the final accuracy of your dataset.
Key tips to ensure accurate Base GNSS data collection:
- Base station placement: The base station needs to be in an open area with a clear view of the sky. Obstructions like trees, buildings, vehicles, etc. will reduce data quality.
- Survey proximity: Your base station should be as close to the survey area as possible.
- Data collection interval: Continuous data at a 1-second interval.
- Satellite connection: Connect to as many GNSS constellations (GPS - United States, GLONASS - Russia, Galileo - Europe, BeiDou - China, QZSS - Asia Oceania) as possible.
- File format: Your Base GNSS data will need to be exported as RINEX (Version 3) data.
The three most commons sources of Base GNSS data for processing LiDAR datasets in ROCK Desktop are:
- On Site Base station: You will have total control over placement and data collection using your own equipment.
- ROCK Base station: If your survey area is close enough to a ROCK Base station, and you have a subscription you can download your data after the flight.
- Publicly available Base station: In the United States this would be the CORS Network.
| Base Method | Pro | Con |
| On Site Base Station | Total Control over placement and data collection. | Not available after the completion of survey. |
| ROCK Base Station | Connected to desired satellite constellations, and available after completion of survey. | May not be close enough to survey area, and cannot be moved. |
| Public Base Station | No equipment needed, and available after completion of survey. | May not be connected to desired constellations, and be close enough to survey area. |
One of the most accessible tools for examining Base GNSS data is RTKPLOT, a free tool that can help visualize your RINEX data.
After loading your Base GNSS data, there are two visualizations you want to focus on:
- Satellite Visibility: This shows the satellites connected to the base station over time. Long, continuous green lines indicate stable connections, which are what you're aiming for.
- Skyplot: This 360-degree view shows the distribution of satellite connections across the sky. Ideally, you want even distribution with minimal gaps, ensuring strong coverage.
It is critical to determine prior to your survey what Base GNSS data you intend to collect and use when you process your data. Lower quality Base GNSS data can be caused by a number of factors such as:
- Base station placement: If a base station is placed too close to obstructions like trees, vehicles, buildings, etc. then your data quality will be reduced.
- Base station not connecting to all satellite constellations: Ideally the base station should be collecting data from a minimum of four GNSS satellite constellations. Collecting data from fewer than four satellite constellations will result in lower quality data.
- Gaps in collected data: If there are gaps in the Base GNSS data, you will not be able to process in ROCK Desktop.