Abstract:

The linear traveltime interpolation(LTI) method is based on linear assumption so that its precision depends on grid division, and the rays transported from the reverse direction are not considered when we recalculate traveltime row by row or column by column,and the computation is unstable in the complex models. Here, we put forward two improvements for the LTI method. First, calculating the minimum travel-time of all grid nodes by all-round cycle strategy during ray tracing. Secondly, inserting secondary nodes in the original grid boundary. Model tests show that the all-round cycle strategy of LTI considers the races from all direction, so it’s more stable for complex models.In the case of same grid division, comparing with the traditional LTI, the LTI method with secondary inserted nodes has higher precision that be improved at least an order of magnitude.At the same time, the calculation speed of our method is faster and time consuming decreases more obviously when the grids become smaller.The calculation speed of our method can be n-10n times than the traditional one’s.

Key words: ray tracing, linear traveltime interpolation, all-around cycle, secondary node