Error in calculation of wall surface

[Anonymous]

It seems to me, I found serious error in wall serface calculation in ArchiCAD 8.1 .

I draw a horisontal wall with thickness 1000, hight 1000 and length 10000.
After that I rotate a copy to 90 and drag the copy for organize cross.
See a picture.

After that I calculate surface of source wall - it is 8 000 000!!! But it is wrong! True surface is 9 000 000. If I see surface of copy, it is Ok.

Can you comment the situation?

[Djordje]

Leo wrote:
It seems to me, I found serious error in wall serface calculation in ArchiCAD 8.1 .

I draw a horisontal wall with thickness 1000, hight 1000 and length 10000.
After that I rotate a copy to 90 and drag the copy for organize cross.
See a picture.

After that I calculate surface of source wall - it is 8 000 000!!! But it is wrong! True surface is 9 000 000. If I see surface of copy, it is Ok.

Can you comment the situation?

The intersecting part is subtracted from one wall. The total is correct, and the concept is also IMHO right.

[Anonymous]

Djordje wrote:
The intersecting part is subtracted from one wall. The total is correct, and the concept is also IMHO right.

Sorry, Djordje. Ican't understand you. As you see at picture the size of surface 1 of wall 1 is 8.000.000. But intersection decreese the surface by 1.000.000 only. Ok, you can say, that wall 1 decreesed two times - for wall 1 and for wall 2. But surface 1 of wall 2 is 9.000.000!!! So, it already decresed. Total surface 1 size is 17.000.000 and it is wrong.

Am I right?

[Anonymous]

There is something a bit strange here. I don't think that ArchiCAD is making an arithmetical error. It is an error about what is being calculated and how it is presented.

I don't know the settings that produced this result but it appears to me that the report is treating the two walls as one assembly. The two wall surfaces forming the upper left corner total 8 square meters, the upper right and lower left are 9, but the lower right is 10 (which doesn't appear any where). The total trimmed surface including the ends is 40 without the ends it is 36. The values of 20, 22 and 42 can certainly be derived from the above surfaces but the results seem strange to the point of meaningless. Perhaps they are being derived based on the material settings of the wall surfaces?

Perhaps there are different settings that would produce a more meaningful result.

[Karl Ottenstein]

Matthew wrote:
Perhaps there are different settings that would produce a more meaningful result.

I'm rushing out the door to ski - the sun decided to bless us today (rare event that is always taken advantage of) ... but I wonder if each wall had a different intersection priority number if then the two walls would not be treated as an assembly? It seems that AC is doing the right thing to me...but my mind is elsewhere! 😉

Karl