The function assignTnull is run on calculated isochrons before gridding. So the minimum entry in the data/color bar is zero. Obviously, when a grid is generated, the color bar starts with zero, say, 0-0.266 s. After some time, say a day, when I pull a grid, the color bar would change starting with a negative number. I also noticed even though I used 0.0033333333333333 (16 decimal places) as cell size, Kingdom 2016 saves it as 0.003333.

IHS customer service advised me to save the color bar so that anytime I retrieve a grid, it will stay the same as at creation time. I’ve done this for all grids but continue to get the same result as indicated above. Any suggestion or advise to prevent this color bar changes?