VTK for GeoPhysical Data – SEG-Y Reader

SEG-Y (also referred to as SEG Y) is a file format used in the geophysical industry for recording digital seismic data. It is an open standard developed and maintained by the Society of Exploration Geophysicists (SEG).  A SEG-Y file consists of a file header followed by a number of traces. Each trace is vertical, stores X and Y coordinate, and contains a number of samples between 0 and a certain depth in the ground. Traces are organized in rows (inlines) and columns (crosslines) and are stored in the file in row-major-order. Our convention is that rows (inlines) are parallel with the X axis, columns are parallel with the Y axis and traces are parallel with the Z axis. So X-Y-Z axes store crossline-inline-depth values.

There are two kinds of SEG-Y data:

2.5 D SEG-Y Data

In this case the data only has one row (inline) and we represent the resulting surface using vtkStructuredGrid.

2.5D SEG-Y surface

3D SEG-Y Data

In this case the data has many rows and by default we represent this data as a Structured Grid (curvilinear grid).

3D SEG-Y data visualized using color mapping and a volume rendering

The X and Y coordinates stored with each trace are used to visualize the position and shape of the data in space. By default the reader produces a VTK StructuredGrid because it preserves the data orientation and shape. The reader has an option to read the data as VTK ImageData, which is useful when the data is parallelepiped that is rotated around the Z axis, as this format is memory efficient and can make data processing faster (See Figure below).

3D SEG-Y data represented as Image Data (aligned with XY axes) and Structured Grid

This reader is available in VTK master. If you have any questions or need help with your GeoPhysical data visualization please contact kitware@kitware.com

Questions or comments are always welcome!

X