This command creates contours from a surface model defined by a grid file. Contouring from a grid employs a different method than from a triangulation network and generally produces contours that loop more. The grid has data points at a regular interval while the triangulation has edges for every point and break line in the surface. The smoothness of the contours depends on the grid resolution. The Smoothing Sub-Division option will internally subdivide the grid cells with a quadratic smoothing algorithm to help create smoother contours. The Hatch Zones option will fill in the specified elevation ranges with hatch patterns or solid color fills. The Create Polyline Topology will create closed polylines for each contour range and will draw a zone text label within each area. This polyline topology can be used in GIS routines such as Polygon Processor.
Select the Inclusion perimeter polylines or ENTER for none.
Select objects: pick a closed polyline for the contour
boundary if any
Select the Exclusion perimeter polylines or ENTER for none.
Select objects: pick a closed polyline for the area to
exclude
Grid File to Process dialog select a .grd file
Contour from Grid File options dialog
Extrapolate grid to full grid size (Yes/<No>)? press Enter
This prompt appears if your grid
extends beyond the limits of your data points in some areas.
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| Contours from tmesh without smoothing |
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| Contours from grid file without smoothing |
Pulldown Menu Location: Surface > Contour from...
Keyboard Command: cntrgrd
Prerequisite: A grid file created by
Make 3D Grid File
File Names: \lsp\contour4.lsp, \lsp\cntr_grd.arx