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Calculating an area in a closed polyline with an island

PostPosted: Wed Dec 05, 2012 7:45 pm
by stevedrew
Trying calculate an area inside an exterior closed polyline that borders an interior closed polyline...

Please refer to attachment:
BPOLY.GIF

Using the hatch command, I can create hatch as shown in the above example and get the area using properties.

I have tried using bpoly with island detection but that does not seem to work either.
Bpoly command.GIF

Is there a Carlson command or AutoLISP program available?

Or am I missing something?

Thanks!

Re: Calculating an area in a closed polyline with an island

PostPosted: Wed Dec 05, 2012 8:41 pm
by ColC
Try area by interior point. It has worked for me. If it doesn't work check that they are 2d lines.

Re: Calculating an area in a closed polyline with an island

PostPosted: Wed Dec 05, 2012 10:02 pm
by tstrickland
An island doesn't work for me in Carlson Survey in area calculations, never has. It ignores the island and includes the area. Also with an island, the perimeter of the island is ignored.
I just manually subtract the inner area. I'm using 2009 embedded, haven't tried it in any newer versions.

Re: Calculating an area in a closed polyline with an island

PostPosted: Thu Dec 06, 2012 2:28 pm
by stevedrew
[quote="ColC"]Try area by interior pTried the ptarea command e.g.

Tried ptarea e.g.:
Command: ptarea
Pick point inside area perimeter:


Polylines are 2D, Elevation = 0
Does not work....

Re: Calculating an area in a closed polyline with an island

PostPosted: Thu Dec 06, 2012 3:48 pm
by Dent Cermak
QUICK FIX: Enclose your area with 2 separate closed polys. Pick a PI as a beginnjing poit and trace endpoint to endpoint half way around and then jump to an interior PI and trace back to the beginning PI. Make 2 separate closed polys. Then use the Area by closed polyline for each poly and add the areas together.

Re: Calculating an area in a closed polyline with an island

PostPosted: Thu Dec 06, 2012 5:12 pm
by stevedrew
Got solution from:
Brian Harris
Technical Support
Carlson Software

You can use the "Area by Closed Polylines" routine under the Area/Layout pull-down. Toggle the "Single Area" and the "Prompt for Exclusion" options and hit OK. Follow the commandline prompts and you should be all set.

Re: Calculating an area in a closed polyline with an island

PostPosted: Thu Dec 06, 2012 8:13 pm
by Dent Cermak
That's why we refer to Brian as "Brain" Harris areound here.

Re: Calculating an area in a closed polyline with an island

PostPosted: Thu Dec 06, 2012 11:08 pm
by ColC
Sorry Steve,

I think my brain must have had a hole in it at the time. I had just had a similar situation to yours a month ago. I thought I had got it as I described but, I had actually used terry's method.
The "Brain" solution sounds like one to remember.(If I can just plug that hole of mine)