Offsetting Complex curves

[Robert Fuchs]

I am being attacked here at my office from new AC users.
Some are working on ccomplex curvingsidewalk for nursing homes and asked me how to offset the curves. i showed them they can use the pline tool and how to add curves as they drawing but they do not want to have to retrace what they just drew to offset the sidewalk. I agree it is time consuming. they said it would be nice to be able to just click an ooffset buttonand give it a distance and it makes a copy of it at the set distance.
Is there a feature like this already or one coming in AC 9? Nothing like training 5 frustrated AutoCAD users. can anyone help, please?

Thanks,

[Anonymous]

Ferenc wrote:
The problem with splines (bezier curves) that (in mathematical sense) there is no "offset spline" t speak of.
If you offset the points (say with the resize command), you will see that the distance is uneven.
The points -say- 5ft away from a spline are not on a spline which can be created by moving the points. Ask any boatbuilder, modeler...

So Karl's method (magic wand with a polyline, offset the polyline) is the best method for approximating an offset.

Very good point Ferenc. I hadn't really thought that through before. I would have imagined there was a solution for equidistant spline curves until you pointed this out.

BTW: You probably know this, but for those who don't the stickler in me feels the need to point out that a spline is a special case of a Bezier curve in which all the anchor points are equally weighted.

[Anonymous]

corollary: the way it works in AutoCAD is that once you lay down the spline and you select it there are bunch of endpoints within the spline, and you can only edit those endpoints, not the original control handles as in ArchiCAD (or Illustrator)

So they are using the "Karl's method" from the start, and that's how they do offset.

So if somebody gives you a hard time on "but AutoCAD can..." ask them to edit the spline (make it curvier or flatter)

[Anonymous]

Ferenc wrote:
corollary: the way it works in AutoCAD is that once you lay down the spline and you select it there are bunch of endpoints within the spline, and you can only edit those endpoints, not the original control handles as in ArchiCAD (or Illustrator)

So they are using the "Karl's method" from the start, and that's how they do offset.

So if somebody gives you a hard time on "but AutoCAD can..." ask them to edit the spline (make it curvier or flatter)

So that's why DWG site plans are such a pain.

[jhonesnow]

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@Robert Fuchs wrote:

I am being attacked here at my office from new AC users.
Some are working on ccomplex curvingsidewalk for nursing homes and asked me how to offset the curves. i showed them they can use the pline tool and how to add curves as they drawing but they do not want to have to retrace what they just drew to offset the sidewalk. I agree it is time consuming. they said it would be nice to be able to just click an ooffset buttonand give it a distance and it makes a copy of it at the set distance.
Is there a feature like this already or one coming in AC 9? Nothing like training 5 frustrated AutoCAD users. can anyone help, please?

Thanks,

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the enchanted wand is the way in to this activity...

stage 1: what is it that you need to make with the offset? lines? - then pick the line (or pline) instrument. A block garden wall? - select the wall device with suitable settings.

stage 2: hit the letter "o" to initiate the offset button. you'll see it appear in the controls (?) pallette. It has the suspend bunches switch on it, and the division settings... multiploe offset is right close to counterbalance and it works the same way.

stage 3: hold down spacebar to get the wand, move the cursor past the brink of the walkway until the polgon shows up on the cursor (like the mercedes, or mark). Click the mouse to begin the offset.

stage 4: drag the offset to where you need it. for accuracy, enter a distance in the x,y, or sweep/point boxes.