Creating Linetypes with Measure and Divide

I’ve been using AutoCAD to create maps since the mid-1980s, and I had to develop a lot of kludges in the early days to get what I envisioned to come out of the plotter.  Significant improvements to AutoCAD over the years have made many of those work-around tricks obsolete, but there are still a few I rely upon from time to time.

For instance, there’s an easy way to align a block along a linear object, such as a line, arc or polyline, even one that has been converted into a spline curve. The result is similar to creating a customized linetype, but is easier and far more versatile. Suppose you need to place a small arrow symbol along a path?  You might not think of the basic AutoCAD MEASURE and DIVIDE commands, found on the DRAW > POINT menu fly-out, because their main purpose is to insert NODES at regular intervals along an object.  However, they both also offer the option to insert blocks.

To begin, select a block and note its exact name, as you’ll have to type it in at the command line. Or, you can create a block, if you need something unique.  For a simple arrow, draw an object like the one below left, then mirror it and join the line segments into a closed polyline, to get an arrow like the one in the middle.  Next, use the solid command to fill it, and then make it into a block called “arrow”, with the insertion point indicated by the highlighted grip, or anywhere on the object’s main axis.


Of course, you could leave the arrow object unfilled, fill it with a hatch pattern, or embellish it in any way to suit your needs. 

Next, create or locate the path along which you want to insert this block at regular intervals, such as this splined curve:


You have two choices for specifying the intervals between the blocks; the MEASURE command prompts for the number of blocks to evenly distribute along the polyline, while the DIVIDE command prompts for the distance between them.

To place nine blocks named “arrow” evenly spaced and aligned with the polyline shown above, issue the DRAW > POINT > DIVIDE command, and respond to the prompts as follows:

Command: _divide

Select object to divide: [ pick the polyline ]

Enter name of block to insert: arrow

Align block with object? [Yes/No] <Y>: [ Enter ]

Enter the number of segments: 10

Nine block references are inserted, aligned with the polyline, dividing the object into ten equal segments between the insertion points:


You may need to tweak a few rotations, but it sure beats inserting and rotating each block manually, especially if inserting dozens or hundreds.

If you prefer, you can respond to the “Align block with object?” prompt with a negative, which will result in all of the blocks aligned the way they were created:


Once the blocks are inserted, you can delete the original object, retain it, give it a width, offset it, etc., for a wide variety of cartographic effects:


Once the command is completed, the inserted objects (whether blocks or nodes) are placed in the previous selection set, so if you wish to delete them and try again, or edit them, you can simply use “Previous” to select them all.

If you are not familiar with the block option for these commands, give them a try.  If you find yourself needing an unusual linetype, they can provide a quick and easy solution.  I’ve used this trick for many different applications; little buses with arrows for transit maps, little fish indicating stream reaches where fish spawn, even to put little tiny horse shoes along a path for an equestrienne event course layout, with different gaps to indicate different gaits.

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