Imagine you have a curve that starts at depth 650 and stops at 700. The curve starts again at 800 and ends at 900. Your scanned (or paper) log does not represent this break as empty space, but as some symbol, such as horizontal bar. You want each step in your LAS file that occupies this no-data zone to have the Null value -9999.
In this case you would:
- First import and calibrate the top half of the image.
- Then import and calibrate the lower half.
- Arrange the image order so the first is showing and digitize that top section of the curve.
- Re-arrange the images so the second image is showing and digitize the lower half of the curve.
- Export as an LAS. Use the depth 650 - 900. Choose an interval.
- Delete the top curve.
- Export as an LAS. Use the depth 800 - 900. Use the same interval.
- Open this second curve in a text editor. Copy the lines from 800 - 900
- Open the first curve in a text editor. Select all lines starting at 800 and paste the copied section over them.
- Replace all values in the third column between 700-800 with -9999 (as described above)
- Save the this first file.
Updated: October 4, 2016