Scale to an area reference instead of length

[samizeton]

Hi everyone. The topic is self explanatory. is there a way to scale an object but to an area reference instead of a length reference ?

Thanks.

[tramber]

To me, it is only possible with the RECTANG command after the first click to give a point...there is an Area option.

[Valentin_CAD · Accepted solution]

@samizeton ,

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@samizeton wrote:

.. is there a way to scale an object but to an area reference instead of a length reference?

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SqRt(Desired Polygon Area/Current Polygon Area)

[samizeton]

The thing is the shape is not regular and i traced it of a pdf. and the only information i have about this shape is its area 

[RobRocks]

Math?

[samizeton]

Math is not really gonna help when the scale factor is an irrational number 

[Kent1Cooper · Accepted solution]

Use SCALE, and the Reference option, and use the square root of the current area as the reference length, and the square root of the target area as the new length.

What is the object?  A Polyline?  And is it always a single object, or would you sometimes want to do this to a multiple selection?  In what form do you have "the only information i have about this shape is its area"?  Is that something that can be extracted from the object, or is it somehow known in another way?

[samizeton]

 an Irregular shape of a plot. the area of which is specific number and i have a not to a scale-copy of it . but I'll try your suggestion and see what comes up as it is as close as it gets to reference scale. 

thanks

[RobRocks]

I don't know but if you have a given area and a desired area, seems like dividing the two will give you a scale factor. 

[Kent1Cooper]

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@RobRocks wrote:

I don't know but if you have a given area and a desired area, seems like dividing the two will give you a scale factor. 

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I has to be the square roots of the areas.  Be careful of the distinction between length [1-dimensional] and area [2-dimensional].

Say you have a square whose area is 4 square units [2 linear units per edge], and you want it to be 16 square units [4 units per edge].  If you divide the desired area 16 by the given area of 4, you'll get 4, and if you use that as a scale factor on the original square, it will become 8 units per edge, or 64 square units -- 4 times as big as you want.

You need to divide the square root of the desired 16 [= 4] by the square root of the given 4 [= 2], to get a scale factor of 2, for a result of 4 units per edge or 16 square units.

[vladimir_michl · Accepted solution]

Use ScaleArea instead of SCALE. This simple LISP tool for AutoCAD and AutoCAD LT is available here:

https://www.cadforum.cz/en/how-to-scale-an-object-to-reach-the-target-area-tip14177

Vladimir Michl, www.arkance.world  -  www.cadforum.cz

[arch_samizeitoun]

@vladimir_michl Thank you for the wonderfull LISP