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{alias:oco}
h2. Name

*oco* — Orthogonal contours

h2. Syntax
{panel:|borderStyle=solid|borderWidth=1|bgColor=#FFFFAA}

*oco* \[*frq* _frequency_] \[*col* _color_] \[*liw* _linewidth_] \[*bsp*] \[*nos*] \[*noadj*] \[*cur*] \[*dar*] \[*trm*] \[*ang*] \[*cod*] \[*cdc*] \[*cdr*] \[*chd*] \[*split*] \[*src*] 

{panel}

h2. Description

Display orthogonal contours from grids and generate drainage areas. 

h2. Arguments

*frq* _frequency_ 
{indent}Indicates density of orthogonal contour lines. Default is 7. Lower number gives higher density.{indent} 
*col* _color_ 
{indent}Will be displayed in color _color_.{indent} 
*liw* _linewidth_ 
{indent}Will be displayed with linewidth _linewidth_.{indent} 
*bsp* 
{indent}Will smooth the lines with b-splines.{indent} 
*nos* 
{indent}Will not seek for the deepest region (which is default).{indent} 
*noadj* 
{indent}Will not adjust the lines to lay slightly above the grid.{indent} 
*cur* 
{indent}Will produce one ortho contour from the cursor position.{indent} 

+Drainage area calculation+
*dar* 
{indent}Will produce drainage areas (which is closely related to orthogonal contours).{indent} 
*trm* _number\_of\_nodes_ 
{indent}Remove drainage areas by minimum _number\_of\_nodes in areas.{indent} 
*ang* _angle_ 
{indent}Remove drainage areas lower than a certain angle between areas.{indent} 
*cod* 
{indent}Combine two drainage areas defined by the two latest cursor positions.{indent} 
*cdc* \[*lin*] \[*col* _color_] 
{indent}Calculate a closed drainage curve for an area defined by the latest cursor position. The result curve is saved in workspace +draincurve+. The curve is smoothed by a spline unless the *lin* argument is used. Color of the curve can be set by *col* and color selection.{indent} 
*cdr* \[*smo*] \[*col* _color_] 
{indent}Calculate closed drainage curves for all drainage areas. The result curves are saved in workspace +allcurves+. The curve is linear unless the *smo* is used. Color of the curves can be set by *col* and color selection.{indent} 
*chd* 
{indent}Change a drainage area defined by the cursor position. This has an expanding effect of the drainge area.{indent} 
*split* 
{indent}Split a drainage area along a line defined by the two last cursor positions just outside the drainage area at opposite positions.{indent} 
*src* 
{indent}The dataset in active is set as the source grid in drainage calculation.{indent}
 
h2. Examples

h3. Ex.1: Orthogonal contours and drainage areas

{noformat:|borderWidth=1|bgColor=#eeeeee}
        z                        ;# Erase screen
       
win demo                 ;# Get demo window (450000 460000 6450000 6460000 1000 4000)
       
spe bgc whi              ;# Specify background color to white
       
mak ran 11               ;# Make 11 random points
       
grp 222 222              ;# Make grid
       
oco frq 14 col bla liw 2 ;# Draw orthogonal contours
       
oco dar                  ;# Calculate drainage areas
       
map drain                ;# Map the drainage areas
{noformat}

The above example produces this image. 

!att:_img_ref^cmd_oco.png!
_Orthogonal contours and drainage areas_

h2. See also

[cal - Calculation algorithms], [mak|mak - Make datasets] _tan_
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