VS3D / VScad3 User's Guide

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VS3D File Menu

1.1.2 Import continued.

"File / Import => Gridfloat (.flt)..." : This will load a United States Geological Survey (USGS) Digital Elevation Map (National Elevation Data "NED") or other file in Gridfloat format. VS3D will search in the same folder for an associated header (".hdr") file that has the same file name prefix as the selected ".flt" file. If found, the header file, which desciibes the contents of the ".flt" file, is read in. The header file should be in simple text (TXT) format. If the header file is not found, VS3D will prompt for the grid dimensions and coordinates.

After a file is selected, the "Import Gridfloat File" dialog appears. This dialog has four settings.


  • "Insert DEM on Layer" : This determines which layer to insert the height values on.

  • "Insert Mode" : This setting determines how imported surface heights are assigned to the existing sculpture grid.
    "Load" - the entire sculpture grid (all layers) is replaced by the imported data. This is similar to loading a sculpture ".vs3" file (from the "File / Load Relief" menu).
    "    Overwrite" - the imported data overwrites the current sculpture grid only within the XY coverage extents of the imported data.
    "    Merge" - similar to "Overwrite" mode, except that the imported data heights are added to the existing sculpture grid heights.

  • "Data Sampling %" : This value determines if the data is sub-sampled before conversion to surface heights. If, for example, the import grid measures 1200x1200, and the sampling is 50%, then every other point in the imported DEM is skipped (making it, effectively, a 600x600 grid).

  • "Height Scale Factor" : This value is a scale factor that is applied to the DEM heights before loading.

In "Overwrite" and "Merge" insert modes, the placement of the imported data on the existing sculpture grid is determined by the current X and Y Data Coordinate scales. In "Load" insert mode, the X and Y Data Coordinate scales are set to the ranges from the imported file (longitude and latitude are mapped the the Cartesian XY plane).

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