Area Calculations in 2013

[Anonymous]

I am trying to calculate the area of the attached file.  Just the Blue section.  Is there a faster way to calculate the area than using the "area" command, then going through and selecting each line, then each arc, over and over again?  I also tried making a poliline that follows the entire pattern at the width I wanted, then using the "area" command for the "object" that is the poliline.  This is faster, but does not give me the correct area.  It says that the calculated area does not take into consideration the width of the poliline.  The width of the poliline is very important in my application, and will sometimes be changed.  Than a new area will be needed with the new width.

I moved from draftsight to autocad hoping to solve this problem, but I still have the same problem.

Thank you,

Anthony

[sthompson1021]

Hi, just a thought on this. If you set the global width of the polyline to 0 the area should be right. If you need to have the width of the polyline at 5 you should be able to offset the polyline by 5 and the area should increase by the right amount.

[Anonymous]

What do you mean by change the global width of the polyline to 0? I have it set at .0847 as of right now. When I use the area command on the polyline, i get an area of 4.8185, but when I calculate it manually I get 4.936.  This has been checked several times to make sure I am not just messing up basica math. When I change the width of the polyline to anything else, say .1, it doest not change the area.

I believe this problem occurs because width of the polyline is not taken into consideration for area, which doesnt really make sense to me, but that is how it was explained to me with draftisight. 

[Anonymous]

By changing the global width of the polyline to 0, there is nothing to select for the area command.

[sthompson1021]

Hi, first I can't open your dwg because I've got 2011 installed on my laptop. Anyway, if you open the properties pallet you can change the global width of the polyline in there if you have the line selected. It will also show you the area of the polyline. When you chage the width of a polyline it changes equally in both directions from the center so it won't change the area measurement. If your trace of the shape was right on the area should be correct. You could try joining the lines and arcs to turn them into a polyline to check it that way. Anyway if you need to change the width of the polyline and have that added into your area measurement, you are better off to offset the polyline anyway and then use a hatch to make it look like a wide line.

[Anonymous]

That just doesnt make sense to me, if you change the global width to 0, how can the area still be 4.8185? It isnt covering the same area that it was when it had a width of .0847. And what do you mean by offset the line to get the added area?

[sthompson1021]

The width of a polyline is measured from the center of the line outward in both directions equally. When you use a polyline to measure an area, the area is calculated from the center of the line. That is why the area doesn't change when you change the width. It sounds like you need to have the width to be actual distance from inside to outside of the polyline. Thats where the offset comes in. If you draw a square that measures 2x2 the area is 4. If you offset that square by 1 to the outside that increases the area to 9. If you hatch the area in the middle it will look like a polyline with a width of 1. I hope you can make sense of my rambling. Maybe someone else will jump in that can explain it better.

[sthompson1021]

If you could save your dwg. down to 2010 I could look at it and maybe come up with another idea.

[Anonymous]

I have saved it down to a 2010, and attached my .dwg file. So if that explains why the area doesnt change when the width changes, why is the area 4.8185 when I calculate it to be 4.936? Where does this come from?

[Anonymous]

I have just been having issues with the area calculations in general.  On a different resistor I made, i used the area command and got 4.5624, which isnt even close.  I used to old program that I am trying to get away from and got 1.5135 for the area.  I am so confused why both draftsight and autocad are messing up the area calculation but this old program CAMtastic that doesnt even run on an OS newer than windows 95 can calculate the area correctly.

[pendean]

PEDIT command's MULTIPL option, select all your blue lines and "JOIN" to become one long Pline (after you close the two gaps), the LIST or use AREA command's OBJECT option to get the area. Use PEDIT>Join's FUZZ Factor option to fix any gaps in the line that would prevent the objects from joining (assuming they are all on the asme plane).

Or close the two gaps I see in the middle and any others, and use BOUNDARY command to create a new "fill" border (you must also pick a fuzz factor to cover any gaps), then LIST or use AREA's OBJECT command on it.

Your posted file is a mess as far as gaps are concerned, otherwise I would have done the above for you.

[Anonymous]

What gaps are you seeing? Just where lines arnt matching up end to end?

[pendean]

You're kidding, right?

[Anonymous]

No, not at all. I am pretty new to Cad. The serpentine pattern is on purpous, and I just fill the outline with a polyline.  On my screen, I seem to have 1 solid line for my polyline with no breaks in the line.  I could have sent you the wrong file.

[sthompson1021 · Accepted solution]

Hi, I'm not seeing the gaps that Dean is, but anyway I modified your dwg to try to explain what I was talking about. I'm not sure why Auto Cad even give an area on a polyline that isn't closed but it's not the area that you want. See my dwg and maybe that will explain it better.

[Anonymous]

Finally, an area that matches what I calculated. I got it to work myself as well. Thank you for the help, I really appreciate it.

[drjohn]

Your DWG (PLINE) is not a mess .... there are no gaps  other than they are just not closed plines.  That would have solved your issue.

Regards,

DJ

[Pentagon2]

Hatch the figure (Draw, Hatch, Add: Select objects) I just winowed the whole thing, look up Area in Properties.