DETECTION STAGES
Our applications are designed to detect errors at every stage of the operation, and these operational stages can also be used to categorise error detection. These stages include procedural, layout compliance, processing, collating and final presentation. The following are examples of each of these.
- Procedural Check: An example of a procedural check is the ability to identify check points in the data. When laying out with RTK, it is normal for each crew to re-survey two or three points from a previous day to compare the values. This checks today’s and the previous day’s base station setup, as well as currently assigned antenna heights. We can identify these by their code, colour code them to identify them as check points, search the database for matching previously surveyed points, display the comparison and highlight any discrepancies that exceed tolerance. This is all done automatically on loading the RTK data. We check for procedural compliance and accuracy, quickly and easily.
- Layout compliance involves ensuring that the postplot positions agree with the preplot positions within the specified tolerance. This is a common check applied on all surveys by both contractors and QCs. Our software flags any points that exceed tolerance for that point type, and also outputs totals and percentages for these points.
- Processing: Our software can process raw RTK, VAPS, acoustic and airgun source data to create comparison datasets. The actual processing procedure itself can also identify problems that might not be otherwise apparent. Raw VAPS data can show up initialisation codes that indicate a bad vibrator position. These can result in elevation errors of several metres if not detected. Processing acoustic data identifies bad transponders and other problems, like bad interpolation, that might adversely affect the final positions. Airgun source reprocessing regularly shows up anomalies in the shot positions. These can come from spurious readings that have not been filtered out, from over smoothing of cross line movement and even from logic errors in the contractor software. The same software that tells the shooting system where and when to fire the guns, also produces the final position. In some circumstances, the guns might fire in the wrong position, but the final data shows them within tolerance. The only way to detect these occurrences is to re-process the data independently. We have the ability to do this in a very efficient batch mode for all currently used airgun configurations, then compare the results.
- As mentioned in the introduction, editing and collation is a major source of errors that we detect. By storing the data in a database after running all daily checks, we can generate our own final data set at the completion of each line or swath. We compare these to the contractor’s final data and resolve any differences before approving the data.
- Finally, we check the header and format of SPS final data if that is the presentation format. We also check that all references in the X file resolve correctly to records in the R and S files.
These are just representative examples of the checks we include in our procedures. There are many more detailed in the Software pages.
Finally in the error section, we can use the previous categories to present the most common positioning errors that occur with different types of seismic operation in an Error Source Table.
To view in detail the capabilities of our software, see Software.
To view the services we offer, see Services.
To view our experience and contact information, see About Us.