I need to have a Surfer file superimposed into another larger region.
I have LIDAR files covering the ground area around a lake (1 meter horizontal resolution). I also have digital lake depth files of the lake. I can easily grid the LIDAR files and the lake depth files, but separately.
LIDAR files are grid-type files so gridding with Nearest Neighbor is quite fast. But the lake depth files are typical field scattered data, which usually require a more sophisticated method such as Kriging.
If I join the two sets of data files...the combined file contains 15+MB of data points. So the large file is a set of both data points already in a grid type but with another set of data arrayed within the LIDAR area in a semi-random pattern.
Nearest Neighbor gridding the large LIDAR coverage takes only minutes. Kriging the much smaller lake depths file also takes only minutes.
But when the two data sets are combined to generate a single Grid file, Surfer slows to a crawl even using Nearest Neighbor. (15 million LIDAR points plus 1,500 lake depth values)
Even a fast grid algorithm such as Nearest Neighbor takes more than 10 hours of computer time (I have a very fast PC with large memory capacity). My preferred method..Kriging will take days of comp time!
Is there a way to actually insert the smaller lake depth Surfer file into the larger LIDAR Surfer file? Effectively 'cookie cutter' the smaller file into the larger coverage?
I know the Surfer file format (in ASCII)...Using the Surfer spreadsheet sub-program...I can replace computed values with my own. But I have been unable to figure out how to replace the lake region LIDAR surface data points with the corresponding grid for the lake.
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