Data retrieval from requestVolumeTraces produces results inconsistent with original segy and requestVolumeSubset.
Using python libraries built from 3.2.6 to read but SEGYImport is version 3.3.255
We've have been trying to verify the fidelity of segy to vds conversions by comparing individual trace data from the original segy with the resulting VDS file. Since we were retrieving individual traces we thought to use VolumeDataAccessManager.requestVolumeTraces but the retrieved data did not match the original in many cases.
Test file was from Volve test set: "/ST0202/ST10010ZC11_MIG_VEL.MIG_VEL.VELOCITY.3D.JS-017527.segy"
Import used no compression, data retrieval LOD 0.
For ease of comparison, we wanted to retrieve the last trace from the file corresponding to inline/crossline 10396, 2800 (trace number 418996 from SEGY). The inline/crossline coordinates convert to inline/crossline indices 435 960 respectively.
Retrieval: trace = accessManager.requestVolumeTraces([[435, 960]], traceDimension=0, lod=0)
This is the result when compared with original trace data:
Now when we use VolumeDataAccessManager.requestVolumeSubset using min/max tuples narrowed to a single trace, our retrieved data matches the original segy perfectly.
minTup = (0, 960, 435, 0, 0, 0)
maxTup = (236, 961, 436, 0, 0, 0)
trace = accessManager.requestVolumeSubset(minTup, maxTup)
My assumption is that we may be misusing requestVolumeTraces, but am unclear in what way.