Some users have asked about digitizing seismic lines in Didger. Here are some ideas that might help:

**Method 1**

This is the simplest method of digitizing seismic lines and involves digitizing the travel time (or depth) for the desired horizons at the shot point locations. This method requires you know the real world XY locations of each shot point location.

- Import the image into Didger.
- Calibrate the image during the import process in the
**Image Registration and Warping**dialog window. Use the Shot Point number as the*Reference X*coordinates and the Time (or Depth) as the*Reference**Y*coordinates. Or put the seismic lines on a digitizing tablet and calibrate the tablet using the parameters described above. - Then, digitize each intersection of a horizon with a shot point line by going to
**Draw | Symbol**(see the crudely drawn image of a seismic section below). - Once all the intersections are digitized, export the data to a DAT file by clicking
**File | Export**and change the*Save as type*to*(*.dat)*. - Open the DAT file in a spreadsheet program (like Surfer or Excel) and for each Shot Point (X value), insert the known world XY locations into two new columns.

Now you have the Shot Point number, the time/depth variable, and the X and Y coordinates for all shot points where they intersect horizons.

**Method 2**

The above would work, but the you may desire greater density of data than simply digitizing points solely at the shot point locations (you may want to digitize the data in between the shot point locations). Here is a method used by one of our other customers. His section was based in Northing, Easting, and Time.

- He calibrated the image using Time as the
*Reference Y*coordinates and whichever geographic value changes most along the line (Northing in his case) as the X axis. - He used shot point locations as the calibration points.
- He digitized along each horizon line as a polyline, and at each shot point location as a point, and manually entered the Easting value as the Primary ID.
- He exported to a DAT file, which gave him Northing, Time, and Easting vales for each shot point location and only Northing and Time values for the horizons in between.
- He opened the DAT file in a spreadsheet program (ie. Excel) and interpolated Easting values between shot points using a linear formula.

*Updated October 20, 2016*

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