Polylines, area, and errors

[joemcd]

I have recently updated from 2012 to 2013 and I am running into a huge problem when doing area calculations. Normally I set up the area I want to calculate the square footage in. Then I execute the BPOLY command. After it is created I simply run the AREA (Object) command and get the square footage.

For example, draw a 10,000 SF space (100' x 100'). Execute the BPOLY command and then AREA (object) and AutoCAD will report that it is 10,000 SF. This is good. If you right click on that poly line it will also report the area.

Now take that same 10,000 SF space and put in a 100 SF (10' x 10') space within it.  Place the 100 SF 10' off the right side and 20' off the bottom of the edges of the larger space. Oh and this 100 SF space has to be excluded from the area calculation. In the past all I would do is draw a line to connect the smaller object to the larger one. Then run the BPOLY and AREA (Object) command and the result should be 9,000 SF, right?

That isn't happening. If you select the properties for that poly line it will not even list an area in the dialog.  It appears that if you have an area witin an area and a chain / line connecting them, AutoCAD will provide an incorrect square footage.

Is this a new "feature" within 2013 or is there a setting that I am missing? Interestingly enough if I do the same thing with LT 2013 I am not running into this problem.

Does anyone have any ideas? My business lives and dies by area calclations.

[joemcd]

I've taken some screen shots to show what it is that I am talking about.

[yogendra.t]

is the polyline edited? if it is edited n no. of times then those many vertises are considered & hence mistakes.

Actually while calculating areas with add & subtract option, it shows graphically different objects but the area calculated is right. Hence adds to confusions.

Have you had the same experience.

[joemcd]

The polyline was created using the BPOLY command. The base drawing was in layer 1, the poly was done in layer 2. After the poly was created that layer was turned off, layer 1 was erased, and layer 2 turned on. Then the AREA (object) command was run. No editiing of the poly its self was performed. Only in the case of example 3 was the incorrect area reported. 

In the real world situation I ran into yesterday the area of the poly should have been 32,000 SF. Instead the area was reported as 30,000 SF. It was as if the same areas were being deducted from the total calculation multiple times. This is not an issue of anything that I am doing since I have executed the same exact process since AutoCAD 2004. 

I am unfamialiar with calculating area with an add or subtract option. Can you explain further? 

[TerryDotson]

So far we have made the following observations on this:

1. The problem appears to have been introduced in AutoCAD 2011, all previous versions appear to calculate the area correctly.
2. The AREA command can return an invalid number, while the underlying API (Polyline Object .Area Property) returns the correct value.
3. One situation that seems to cause the problem is when a segment of the polyline follows a return path across a previous portion of the polyline.

In an effort to help AutoCAD users check drawings for cases of incorrect area, we have produced a freeware application that evaluates all polylines in model space and compares the area reported by the AREA command to the area reported by AutoCAD's own API (the Area property).  It can be found in the Free Stuff section of the site below, look for the PAUDIT.ZIP item.

[joemcd]

Thank you for posting that. Can I contact you privately about the command? I does not seem to work on my 2013 copy of ACA.

[TerryDotson]

Yes, you can email me at dotson [at] dotsoft [dot] com.