Global Mapper v25.0

AltaLIS DEM Terrain data from Alberta

geoltech
geoltech Global Mapper User
Has anyone loaded the AltaLIS data from Alberta, Canada? Did you load the data as three separate files or could it be loaded in a group?

The data is delivered in three file types. 
  • gnp files - masspoints 
  • ghl files - hard breaklines
  • gsl files - soft breaklines

ASCII SPECIFICATION

masspoint file:

Point id, X coordinate (UTM decimal meters), Y coordinate (UTM decimal meters), Z elevation value (decimal meters). 

Hard/soft breakline file:

Line id

start point X coordinate  Y coordinate and Z elevation

END

NOTE:  A -9999 value indicates that there is no elevation data for the location.

ASCII FORMAT SAMPLE

POINT FILE (GNP):

412,417338.59614,5900797.10471,1360

439,416996.93548,5900788,1440

452,417229.22581,5900781.70968,1400

457,417331.73333,5900779,1360

458,417695.77419,5900778.45161,1320

482,417900.85246,5900769.67213,1280

483,417327.3,5900769.5,1360 

HARD LINE FILE (GHL):

            70724

427613          5894574      -9999

427635          5894558      1278.46338

END

            312751

427635          5894558      1278.46338

427660          5894498      1278.46338

END

            70723

427552          5894524      1278.46338

427613          5894574      -9999

END

            312753

427660          5894498      1278.46338

427664          5894454      1278.46338

END

SOFT LINE FILE (GSL):

            72501

418605.32803          5900775.9117      1240

418617          5900666      1240

END

Tagged:

Answers

  • kfroese
    kfroese Geotechnical Engineer Trusted User
    Answer ✓
    Yes. I imported a bunch for some projects. Wrote a script to automate the process since we had several sites to process. I imported the masspoints as points and the other two files (hard and soft breaks) as "point and lines". When I generated a grid, I turned on breaklines. Gave a reasonable surface considering the (in)accuracy of the data.