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- Contour Menu
-
- Specify grid:
- Specify an x,y grid over which contouring will be done. This can be either a regular
- grid or one that passes through all the data points.
-
- Nearest neighbour interpolation:
- Interpolation of missing data based on n nearest neighbours - fastest algorithm.
-
- Akima interpolation:
- Bicubic spline interpolation based on the method of Akima (1978). (Akima H.A.
- A method of bivariate interpolation and smooth surface fitting for irregularly
- distributed data points. ACM Trans. Math. Software 4, 2 (June 1978), 148-159.)
-
- Shading mode:
- Sets contour drawing mode to shading. Contour levels are shaded either in a grey scale
- pattern or in colour. An existing line mode contour map is redone in shade mode.
-
- Line drawing mode:
- Sets contour drawing mode to line drawing. Contour levels are followed by a line of
- selected colour, thickness, smoothing and labeling. An existing shade mode contour map
- is redone in line drawing mode.
-
- Shading settings:
- Allows the setting of contour map cosmetics for shading mode, such as colour, shade key
- positioning and configuration. More specifically:
- Shading type: Ñ Colour vs Grey scale patterns : Either a range of colours from the
- default colour map or grey scale patterns from a range of 32 can be
- used.
- Shading Key: Ñ Font details and number format : Set font and number format details
- for the shade key.
- Ñ Value range position : Draw shade value range to the left or right of
- key.
- Ñ Box height, width and number of key columns : Specify size of key and
- the number of columns to use.
-
- Contour settings:
- Allows the setting of contour map cosmetics such as label positioning, smoothing, line
- thickness, colour and label font details. More specifically:
- Line details : Ñ Minimum length : Only contour lines of this length are plotted.
- Ñ Smoothing - screen based : A cubic spline is fitted through the data
- points - with Segment length the length of line segments plotted and
- Natural cubic spline or s'''(x)=c''' (third derivative of spline
- through end segments = third derivative of unique cubic through
- first four and last four points) end conditions for spline.
- Laserwriter based : Uses postscripts bezier splines for smoothing
- line segments - these curves do not pass through the data points.
- Screen plus Laserwriter based : A combination of above which
- possibly results in the best result for laserwriter output - try using
- a Segment length of 0.2 cm.
- Ñ Colour : Line drawing colour.
- Ñ Dash Pattern : Line drawing dash pattern. Dash lines can be specified
- by entering the number of points for the solid part followed by the
- number of points for the blank part and so on, e.g. 4,2,2 selects a
- dash line with 4 points solid, 2 blank, 2 solid and 2 blank before
- repeating.
- Ñ Linewidth : Point size of line width - use fractional size to do
- hairlines on the laserwriter, e.g. 0.25.
- Label details : Ñ Horizontal vs line following labels : Labels can either be drawn
- horizontally or made to follow the slope of the contour line. If they
- are drawn at the same slope as the contour line then an approximate
- vector font is used on the screen but correctly rotated fonts are
- plotted on the laserwriter.
- Ñ Minimum space between labels : This amount of space is left between
- labels.
- Ñ Maximum curvature change for labels : This restricts label plotting
- to parts of the line that have a changing slope less than specified.
- Ñ Frequency of sampling points when placing labels : When placing
- labels ContourMap scans through the points of a contour line looking
- for candidate positions. This parameter determines the granularity of
- the scan - the lower the number the more points are looked at.
-
- Add contour:
- Select the contour levels to draw either as individual levels or as a range. Each level is
- drawn with the currently selected cosmetic options.
-
- Remove contour:
- Remove an already drawn contour level.
-
- Redraw contour:
- Redraw selected contour levels with the currently selected cosmetic options, overriding
- previously used settings for the levels chosen.
-
- Hide selected contour segment:
- Hides contour segments that have been selected by clicking on a contour label belonging
- to the segment - useful for masking out areas of the map that might have doubtful data.
- Hidden segments are redrawn when Redraw contour is chosen.
-