A simpler solution might be to use a polar planimeter (http://en.wikipedia.org/wiki/Planimeter).
This is an instrument to measure area on paper. They were used a lot before GIS software was developed (and numerical integration for chemistry instrument outputs). I had to use them as an undergrad because some of my profs still liked them for situations like yours. My brother bought one for me on ebay a couple of years ago. A quick look on Google shopping found a couple of models for under $100. You won't need an expensive modern engineering one (which cost $300 to $5000+). Here's my Google product search for "polar planimeter": http://www.google.com/products?client=safari&q=polar+planimeter&oe=UTF-8&hl=en&show=dd&sa=N&lnk=next&start=10 and an example planimeter that is listed on ebay: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220667546556&hlp=false&rvr_id=150273174373&crlp=1_263602_304652&UA=M*S%3F&GUID=3e73079011d0a09c1405f165fff0f22b&itemid=220667546556&ff4=263602_304652#ht_500wt_1058 (as a disclaimer, caveat emptor especially for any web purchases. I have no idea what this seller or actual product are like and am including it only as an example). On Wed, Oct 6, 2010 at 4:33 PM, Aaftab Jain <aaft...@hotmail.com> wrote: > Hello, > I am trying to estimate the area of irregular polygons drawn on graph paper > with a known scale. > > I currently have 50 sheets of graph paper (one each for my 50 sites) with > hand drawn maps indicating different substrates, centered on a focal point. > The side of each square in the graph is 5m. I would like to draw concentric > circles around the focal point (15m, 30m, 45m etc) and estimate the area > under each circle/annulus that falls within one polygon (substrate) or the > other. > > Is there any simple graphing/blueprint software which can take scanned graph > paper with a known scale and generate estimates of area? Could I possibly do > this in Arcview 3.2 without importing any UTM data? Essentially, I would like > to look at a map and say: The area of short grass within the 1st concentric > circle (0-15m) is 400 m sq. and the rest is bare ground, etc. > > I understand that my alternate solution is to physically count graph squares > within each polygon and estimate the number of partial squares, but I would > like to be as accurate as possible. Further, making that same estimate > repeatedly would generate a different area each time. > > Thanks for your suggestions, > > Aaftab Jain > Contract Biologist. > Albuquerque, NM. > > ****************** aaft...@hotmail.com ******************* > >
