ConTour Lisp Notes

  Unzip files to Autocad support directory or any directory in Autocad's search path.
Type (load"ctl_w8") at the command prompt to load routine.  Type "CTL" at the command
prompt for option list.

Command: ctl

			1. Draw Triangulated Surface.
			2. Draw Contour Lines.
			3. Swap Triangle Pairs.
			4. Re-point Contour Lines.
			5. Color Objects.
			6. Read/Write CSV Point File.
			7. Annotate Contours.
			8. Create 3D Mesh.
			S. Cross Sections from Contours.
			A. Area Calculations.
			Q. Quantity from Surface.
			R. Replace Individual Points.
			X. Import Excel Point File.


    Option 1 creates a triangulated surface from all points found on layer "CTL_PNT".
 It prompts to check points before the surface program runs.  If any points are closer than 1.0
unit apart or there are duplicate points in the drawing, the program will hang.  If too many of
your points are closer than 1 unit and you can't move or delete them, you'll have to scale all
of the points up to create the surface and then scale it back down to the original scale.  The
check option will delete any duplicate points and draw a circle on layer "CTL_PTMP" around the
points closer than allowed.

More points don't necessarily create a better contour map but will only increase the dwg size.
Don't use any more points than the resolution you need.  Option 6 or X import on layer CTL_PNT.

  Option 2 draws plines thru each triangle surface on temporary layers, then selects
all lines on each elevation, joins them and asks if you want to create spline fit curves.
Spline curves take up a huge amount of drawing space and lose accuracy on sharp contour
corners if not enough points are supplied.  If successfully joined/splined, it changes
        each contour to layer CTL_CONT and deletes all temporary layers.



  Option 3.   You may need to swap triangles to force adjacent sides to run straight down
a ridge line or up a valley line.  If you swap triangles, the program moves all points on
layer "CTL_PNT" to layer "CTL_PTMP".  Every time you create a surface with option 1, the
program erases any existing surface created on layer "CTL_TIN".  The points were moved so
you don't accidentally resurface and lose any swapped triangles.  Just keep running option
2 until you get the contours the way you want.  Option 2 automatically erases any existing
contours on layer "CTL_CONT" and re-contours.

  Option 4  uses the MEASURE command to create more points along existing contour lines.
You may want to do this to create a more dense surface model to use with the 3D Mesh
option 8.  More on that later.  This option erases all existing points on layer "CTL_PNT"
so make sure you have a backup point file before using this option.



  Option 5.   This switches to a front view, uses the latest contour spacing with the left
and right limits to select and color contours.  If you run this option before option 2,
it will prompt you for a spacing distance to use.



  Option 6  imports any xyz comma separated point file onto layer "CTL_PNT" or writes any
  selected points on layer "CTL_PNT" or "CTL_PTMP" out to a comma separated point file
  and deletes all selected points from the drawing.



  Option 7 annotates by picking a point on any contour line. It will prompt to either
break the contour line or place the text above the line.  Drag the cursor to the right
to align the text.  It will prompt you for a text size so you should check for clearance
between contours.  It reads the elevation from the pick point so you don't have to type
anything.  Occasionally it misreads the elevation by 1 and writes a wrong elevation like
5999 instead of 6000 (it's a fuzz factor error).  I know it's painful but you might have
to manually fix this.  The text is written at that elevation on layer "CTL_CTXT".
           




If you colored your contours with the Major/Minor option, the major lines should already be on
even elevations.  50 unit contours spaced at 5 show up above.  A 20 unit contour spaced at 5
  should all be even 100 units or 40 units spaced at 5 should all be 200 unit elevations.


  
  


  Option 8 creates a 3Dmesh.  It asks whether you want to sample for points or 3D faces.
It prompts for a lower left and upper right point for the mesh boundary, grid spacing, and base
elevation.  You can press "A" or "B" to ignore any points above or below the base elevation. It
selects entities in the drawing with a crossing window the size of each grid spacing and takes
an average of all elevations it finds.  If it finds nothing in a crossing window, it uses the
base elevation. You're limited to 256 x 256 on any one grid.












  Option S creates cross sections from contours on layer CTL_CONT.  You need to draw a "LINE"
over the contours to section.  It searches along the section "LINE" with a crossing fence and
will prompt you for a fence distance.  If the fence is larger than the smallest contour spacing,
you could miss some contour points.  It will prompt for a starting station if your sections are
equally spaced and you want to add stations to your profiles.  It only takes integer values. You
can always overwrite the default station number and reset the forward spacings.  The profiles are
drawn left to right from the direction the section line was drawn.  If you get it backwards, you
can either rotate the section line 180 degrees or just mirror the profile since it's center based.
This only works while in Plan view of World Coordinates. Don't change pline widths before using this.

  Option A calculates areas by using the boundary command.  It uses the pick point
as the text location and will prompt for a text size.  It temporarily displays a red
         boundary and prompts you to accept or decline the area shown.











     Option Q calculates quantities from a triangulated surface relative to a base elevation.
The total surface area must remain constant and you derive the actual volume by the difference
between each surface change.  The example below only shows the need to set the base elev. below
 any anticipated excavation elevation. The default base is the lowest triangle point and can
 remain unchanged for fill quantities, but the actual volume is still the difference between
          surface changes since the world ain't flat. ( I don't think it is.)
                     This only works on triangulated surfaces.











     Option R inserts points from an xyz.csv point file one at a time and allows you to
 drag a box around any existing nearby points to erase.  This is just an easy way to replace
 individual points if you're running incremental quantity surveys with option Q.  After all
  points have been inserted, it gives you the option of saving all points as an incremental
    backup point file with a (YYYYMODD.csv) default file name or whatever name you want.
  



     
     


  Option X imports Excel point files.  It was written for files created by survey
             data collection gizmos that write point files with 5 fields:

          Point #,  Northing,  Easting,  Elevation,  Description (if any)

Northings to a surveyor are Y values to Autocad and Eastings are X values.  They usually have
the choice of writing these files as N-E or X-Y but you never know.  Autocad requires the
input as x-easting, y-northing, z-elevation so this gives you the option of switching the X-Y
fields.  It also changes the current PDMODE point style to an "X".  If you choose to insert
point #'s and descriptions, they're written at 1/2 point size to the sides of each point
on layer "CTL_PTXT".  This will still read any "xyz.csv" file incase you need to swap X-Y.
This loads a separate visual basic function and requires you have Microsoft Excel installed.
I've only tested this with Excel 2000.