topic Re: Offsetting Complex curves in Modeling

Offsetting Complex curves

Robert Fuchs — Wed, 01 Sep 2004 16:37:53 GMT

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,

Re: Offsetting Complex curves

Anonymous — Wed, 01 Sep 2004 17:24:37 GMT

the magic wand is the key to this operation...

step 1: what do you want to create with the offset? lines? - then pick the line (or pline) tool. A brick garden wall? - select the wall tool with appropriate settings.

step 2: hit the letter "o" to activate the offset button. you'll see it show up in the controls (?) pallette. It has the suspend groups switch on it, and the division settings... multiploe offset is right next to offset and it works the same way.

step 3: hold down spacebar to get the wand, move the cursor over the edge of the sidewalk until the polgon appears on the cursor (like the mercedes, or checkmark). Click the mouse to start the offset.

step 4: drag the offset to where you want it. for precision, enter a distance in the x,y, or radius/angle boxes.

HTH
Wes

Re: Offsetting Complex curves

Robert Fuchs — Wed, 01 Sep 2004 20:02:42 GMT

Thanks, i have shown them a few different options to do the same thing so hopefully they will quit bothering me about it now. they still say it would be much easier to just have an offset feature. i appreciate your help.

Re: Offsetting Complex curves

Djordje — Thu, 02 Sep 2004 19:08:20 GMT

Robert wrote:
Thanks, i have shown them a few different options to do the same thing so hopefully they will quit bothering me about it now. they still say it would be much easier to just have an offset feature. i appreciate your help.

You do.

Their problem is, they still think in lines.

Make them work in 3D window exclusively. Who comes to work after three days deserves to stay.

Oh, yes - and all the backgrounds have to be white!

Lack of sleep, bright lights and extra caffeine are mandatory!

😉

Re: Offsetting Complex curves

fuzzytnth3 — Wed, 08 Sep 2004 01:56:43 GMT

Robert wrote:
I am being attacked here at my office from new AC users.
Some are working on ccomplex curvingsidewalk for nursing homes

I can't remember if it is a default line type that comes with ArchiCAD but we sometimes just use a "paving" linetype line/spline rather than drawing the actual lines/splines. Depending on the drawing scale I just have to tweak the spacing of the linetype to get it approximately to the correct width.

I also find that it is sometimes easier (and accurate) to create a line by magic wanding the "base" line with the wall tool.

For example I had to draw a complex site boundary with an exclusion zone 25m wide centered on the boundary line. By using a wall with a thickness of 25m and using the centre reference wall type I got an accurate offset which I then traced using the arc tool. I could also have "exploded" the wall and deleted the fill instead.

Re: Offsetting Complex curves

Anonymous — Fri, 18 Jul 2008 19:21:33 GMT

Its much better to use autocad for this task. Splines dont offset on archicad. I tried converting the splines into walls then exploding them
and pick up their fills. (I wanted to make a walk way around a park)
But I ended up with a bunch of fills. Tried to consolidate them. I tried the consolidate fills option (The new shiny tool in rel 11-The first time I used it) And the program quits! What a bummer!

Re: Offsetting Complex curves

Anonymous — Fri, 18 Jul 2008 19:44:55 GMT

It did work after some cleaning of the fills converted from walls.
Any way. It is much simpler to do this organic turns and twists in autocad, offset them to do walkways road ways and then inmport to archicad.

Re: Offsetting Complex curves

Karl Ottenstein — Fri, 18 Jul 2008 21:30:01 GMT

jocontreras wrote:
Its much better to use autocad for this task. Splines dont offset on archicad.

While splines will not magic-wand offset, polylines will. Draw your spline, select the polyline tool and offset, magic wand the spline. Depending on the complexity (concavity) of the spline mass, you may be able to offset arbitrarily or only some fixed distance.

The polyline uses true curves to interpolate the offset.

Close off the ends of the result, and you can magic wand a slab (your sidewalk), fill, or whatever into the enclosed space.

Is AutoCAD really better?

Karl

Re: Offsetting Complex curves

Anonymous — Sat, 19 Jul 2008 12:00:39 GMT

Thank you Ill try that.
Autocad is not a better program but for making roadways, walkways
I have to recur to it. Ill see if your method makes me change mymind.

Re: Offsetting Complex curves

Anonymous — Sat, 19 Jul 2008 15:52:23 GMT

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.

Re: Offsetting Complex curves

Anonymous — Sat, 19 Jul 2008 17:01:59 GMT

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.

Re: Offsetting Complex curves

Anonymous — Sat, 19 Jul 2008 18:08:49 GMT

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)

Re: Offsetting Complex curves

Anonymous — Sat, 19 Jul 2008 21:06:40 GMT

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.

Re: Offsetting Complex curves

jhonesnow — Thu, 19 Jan 2023 12:09:17 GMT

@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,

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.