Contour from Grid File

This command creates contours from 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 breakline in the surface. The smoothness of the contours depends a great deal upon the grid resolution. When the command is executed, you will be prompted to select inclusion/exclusion perimeter polylines to limit the contours to certain areas. If no perimeter polylines are selected, the entire grid will be contoured. After selecting a grid file to contour, the below dialog will appear.

Default Contour Layer To Grid Name: When enabled, this toggle will automatically set the Contour Layer to match the grid name. For example, a grid named "Topo.grd" would default to draw contours on the "Topo" layer.

Prefix Hatch Layers With Contour Layer: When enabled, this toggle will use the Contour Layer as a prefix for all of the hatch layers. For example, if the first hatch zone is set to be drawn on the "Zone 1" layer and the Contour Layer is set to "CTR", the actual layer name of the hatch will be "CTR Zone 1".

Set Index/Label Layers by Contour Layer: When enabled, this option will automatically set the Index Layer and the Text Layer to be the same as the Contour Layer. However, you may also specify a prefix or suffix for each layer. For example, if the Contour Layer is set to "CTR" and the Index Layer Suffix is set to " Index", then the index contours will be drawn on the "CTR Index" layer. It is important to note that this option only sets these layer names when the command is first executed or when the above dialog is opened, meaning that you may still override these layer names if you wish.

When the toggle is enabled, this value will set the interval for the contours. For example a value of 2 will draw contours along the grid values of 2, 4, 6, 8, etc. The first value contoured will be the first value divisible by that contour value. For example, if an interval of 3 is selected for a grid that ranges from 5 to 20, the first contour will be drawn at a value of 6.

When the toggle is disabled, this value(s) will set the specific value(s) to contour. For example, if a value of 10 is selected, only one contour will be drawn where the grid has a value of 10. Multiple contours may be drawn by entering values separated by spaces. For example, entering "10 12 16" into this text box will draw contours at values of 10, 12, and 16.

Index Layer: This sets the layer for the index contours. You may select an existing layer by clicking the Select button.

Color: This button will open the color palette, where you can select the color for the index contours. Please note that this does not set the color of non-index contours.

Index Interval: This value sets the interval of the index contours. This value will default to be the Contour Interval multiplied by 5.

Line Width: This value sets the width of the index contours. The non-index contours will have a line width of 0 by default.

Label Layer: This sets the layer for the labels. You may select an existing layer by clicking the Select button.

Color: This button will open the color palette, where you can select the color for the index contours. Please note that this does not set the color of non-index contours.

Text Size: This value sets the height of the text in drawing units.

Break Offset: This value sets the distance between the end of the trimmed contour and the start/end of the text. This value is only used when the Break Contours at Label toggle is enabled.

Min Length to Label: This value sets the minimum length of contours to be labeled. For example, if this value is set to 10, a contour with a length of 5 will not be labeled.

Label Index Contours Only: When enabled, this toggle will only add labels to index contours.

Break Contours at Label: When enabled, this toggle will break the contour line near the label, making it easier to read the labels.

Draw Broken Segments: When enabled, this toggle will draw the broken segments of the contour (the portion of the contour under the labels). These segments will be drawn on the layer specified to the right of this toggle.

Label Contour Ends: When enabled, this toggle will draw additional labels at the ends of contours. This option will not draw additional labels on contours  draw as closed polylines.

Draw Box Around Text: When enabled, this toggle will draw a box around the text labels.

Align Text with Contour: When enabled, this toggle will align the label with the contour itself. When disabled, labels will be aligned horizontally.

Hide Drawing Under Labels: When enabled, a WIPEOUT entity will be draw around the labels, hiding the contour and any other linework underneath it. This option has the same visual effect as breaking the contour at the label, but allows you to retain a continuous contour.

Draw on Real Z Axis: When enabled, labels will be drawn at the same elevation as the contour. When disabled, labels will be drawn at zero elevation.

___ Labels Per Contour: These radio buttons set the number of labels to draw on each contour.

Label Per Distance: This radio button will draw a contour label on a regular interval along the contour, set by the Distance Interval value.

Low-High Slider Bar: This slider bar controls the degree of smoothing. This is based on Bezier smoothing, which holds all the original points calculated from the grid and only smooths between the calculated points.

Apply Outlier Reduction Filter: When enabled, this toggle will remove spikes in the contours that don't follow the general trend direction.

Reduce Before Smoothing: When enabled, this toggle will apply the Reduce Vertices function to the contours before smoothing. The Offset Distance is the maximum distance the contour is allowed to move when removing vertices.

Smoothing Subdivision Levels: This option will internally subdivide the grid cells with a quadratic smoothing algorithm to help create smoother contours.

None: The contour zone boundaries will not be drawn. Only the contours themselves will be drawn.

Hatch Zones: This option will draw the contour zone boundaries and hatch them according to the below dialog. When this option is selected, you will be prompted to pick a location to draw a legend. It is recommended that you select an inclusion boundary when using this option even if you are contouring the entire grid.

The above dialog controls the appearance of the hatch zones. A description of each column is given below. Note that you may need to scroll down to other pages to view all of the contour zones.

Elevation: Sets the maximum contour value for the zone.
Range: Displays the range of values included in the zone.
Color: Sets the hatch color for the zone.
Pattern: Sets the hatch pattern for the zone.
Scale: Sets the hatch pattern scale for the zone.
Layer: Sets the layer for the hatch pattern.

Clear: This button will clear all settings in the dialog.

Auto: This button will display the below dialog, which will let you automatically populate each hatch zone with various properties.

Starting Zone: This value sets the first zone to be modified. If this value is set to 1, all zones in the dialog will be modified. You can toggle the various options on this dialog to only modify certain properties of each zone, however.

Set values: When enabled, the values of each zone will be modified. The Starting Value sets the value of the first zone selected. That value will increment by the Value Interval value.

Set Colors: When enabled, the colors of each zone will be modified. There are two ways to set the colors of the zones, controlled by the Set Gradient Colors option.

When Set Gradient Colors is disabled, the colors for each zone will be defined by a Starting Color # and a Color Increment. The Starting Color # relates to a color in the CAD color palette. The Color Increment sets the color for the next zone. For example, if the Starting Color # is 10 and the Color Increment is 2, the second contour zone will use color 12. The default values of 10 and 10 will create a rainbow color gradient. Similarly, a Starting Color # of 11 and a Color Increment of 10 will produce a lighter shade of the rainbow gradient. It can be difficult to create other color gradients with this system, but the other method of setting color allows for easier selection of other gradients.

When Set Gradient Colors is enabled, you will be able to set color gradients by selecting a Low, Medium,  and High color value. All intermediate colors will be selected automatically. It should be noted that this command can only use the colors from the CAD color palette, which includes 255 colors. As a result, attempting to use this option with a large number of hatch zones may result in some hatch zones using the same color.

Set Pattern: When enabled, the pattern for each zone will be set to the selected hatch pattern.

Set Scale: When enabled, the hatch pattern scale for each zone will be set to the Scale value.

Set Layer: When enabled, the layer for each zone will be set to the Layer value. You may select an existing layer by clicking the Select button.

Create Polyline Topology: This option will draw the contour zone boundaries, but will not hatch them. This option will add an extra label in the zone boundary to indicate the range of grid values in that zone. This can be useful for GIS applications in other modules.

Prompts

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.