Importing ASC to mesh issue (Docofossor Plugin)

I’m trying to import terrain data from an ASC file (.txt) to mesh using grasshopper (docofossor plugin). Can anybody explain this issue I’m having where some data is being projected downwards?

The original txt file:

Changing NODATA_value from -9999 to 0 seems to make no difference.

-9999 values are still located at the end of the txt list despite NODATA_value being changed to zero. I tried simply deleting these values but I assume it’s not that simple because then I get this error.

Screenshot 2021-03-19 113031

Any help would be appreciated, thanks!

[Context: I’m trying to find a method of importing large terrain data as accurately as possible without having long lag times. I need a method of sculpting the terrain, while holding to certain parameters (ie. specific slope) and then easily measuring the volume differences made by the sculpting changes. In case anyone has advice on this.]

after_2.txt (12.9 MB)

Original text file as reference

Try replacing the -9999 values with 0 instead of deleting them. The ImportTopo component in Heron can also handle these ASC files as shown in the image below. A boundary needs to be set for this component, so I grabbed the topoExtent curve and inset it 10 to trim off the mesh that goes to 0.