A strength of Surfer is its wide range of supported file formats. This strength extends to gridding as there is a laundry list of supported import data types to create a grid from. Included in the list are LAS and LAZ files, meaning Surfer has the ability to directly grid LiDAR data without first creating a point cloud. Utilizing this direct gridding technique can reduce your eventual contour noise thanks to the specific set of import options tailored to LiDAR data.
These options are included in the LiDAR Import Filtering dialog. The LiDAR Import Filtering dialog offers filtering options that can reduce point density, reject inconsistent data points, and set exact XYZ specifications. For this workflow, to reduce contour noise we are using the Sample Filtering | Nth point option. The Sample Filtering options are used to thin data.
When the Nth point box is checked any number entered will filter out every Nth point of the LAS fie. By setting the value to 2, half the overall points in the LAS file are filtered out. Reducing the total number of data points from 8,840,106 to 4,420,053. If it was desired to remove every third point one would enter the value as 3, and so on.