I am attempting to interpolate the elevations of data sets of cross-shore survey transects. The data set size range from 50k to 300k points with ~100m between the transects and 1-5m between the points within a transect. Find an image here. Apologies, I'm still working on quickly drafting figures in GRASS.
I interpolated the data to a 2m resolution raster with v.surf.rst. I used the default parameters and set a mask based on the data's concave hull. During the computations I received the following messages:
Ignoring xxx points (too dense)
WARNING: Taking too long to find points for interpolation - please change the region to area where your points are. Continuing calculations...
The RMSD which GRASS output with the rasters averaged about 0.35m absolute and 3% of the range. Can anyone tell me if these errors are typical?
I also tried to set scalex and theta (other params were default), but during the computation I received this warning:
WARNING: Overshoot - increase in tension suggested. Overshoot occurs at (1340,1023) cell. Z-value -779923520635822222878965760.000000, zmin -8.433820, zmax 3.060190.
And one of the cells had that large negative value.
I don't really know how to tune the parameters. I'll probably script an optimization using the -c flag, if it seems warranted after a quick lit review. Any other suggestions on changing the default params?