How it Works (Optimising Volumes)
We all want to work fast and there’s nothing more frustrating than clicking on a section and waiting, waiting, waiting for it to display. With so many 3D surveys at our fingertips, we could get used to the idea that digging through thousands of inlines and crosslines will take a while.
Or instead, we could use Optimised Volumes and retrieve our data in a flash.
Even without optimised volumes, Insight is very fast. Our dugio data format was designed for high performance from the very beginning!
What’s an Optimised Volume?
When interpreting, we want to see the data as fast as possible, but we only need to see a few slices or sections at one time. Optimised volumes help Insight read just the data it requires for the display.
When loading seismic, Insight can create extra optimised volumes. Each one is organised so that reading a slice in one direction is as fast as possible.
For time-slices, Insight reads from the TWT optimised volume. For inline sections, Insight reads from the Inline optimised volume. It does all this automatically.
Because of the way the optimised volumes are written, very little unnecessary data is read or transferred. Furthermore, the optimised volumes can use compression to reduce the amount of data even further!
The result is dramatically faster displays for even the largest volumes of seismic.
8-bit or 16-bit?
To save storage space and boost speed even further, optimised volumes can be compressed. 8-bit compressed volumes are much smaller and faster than their 16-bit counterparts.
When compressing data, some precision is lost. This sounds alarming, but don’t worry, Insight has it covered! Whenever calculations are run or data is exported, Insight uses the original, highest-quality version of the data. When you view the data (and you want it NOW), Insight uses the optimised volume. The difference in quality when displaying is nearly imperceptible.
The 8-bit volumes have about a 0.4% loss in precision. Switching to 16-bit optimised results in a much smaller 0.0015% loss, but the data is twice as big.
For best performance, we strongly recommend using the default, 8-bit optimised volumes.
What about gathers?
For gathers, the speed boost can be bigger, but so is the amount of space required for the optimised volumes.
There’s not much benefit if you are looking at single gathers, or whole gathers at a time. However, they definitely help if you are inspecting common-offset sections on inline, crossline and horizontal planes.
Viewing a common-offset horizontal slice on a large volume is almost unusable without a horizontal slice optimised volume.
So what is the drawback?
This boost in performance comes at the cost of additional disk space. The default settings (the 16-bit main volume and three 8-bit optimised) uses about 50% more space than a 32-bit SEG-Y.
If you have the space then it’s a mistake to interpret your data without them!