Latest Contributions by DavidStockdale

That may be, but I think the abstraction (circle) would work for me in this situation, since this is for a programmatic EIS and they are wanting to know the effects of different weed treatments over a large area, not a specific project site. The 10% per year was the approximate minimum rate of spread of the weeds as estimated  by the resource specialists. The rate could be as much as 24%, and I would model that as well. ... View more

I tried using your Excel idea and compared it with manually doing 5 buffers in ArcMap, using your formula for the buffer distance. Doing it in Excel got quite different buffer distances than doing it in ArcMap, but the end result was extremely close, 99+ percent.  So I'm rather puzzled as to why that should be. Year Len Area Buffer Distance Acres ArcMap/Excel Len (ArcMap) Area (ArcMap) Buffer Distance(ArcMap) Acres(ArcMap) 0 582477.514 47218070.03 8.1064 11668 1.000000 582477.514 47218070.03 8.1064 11668 1 629695.584 51939877.03 8.2484 12834 0.998870 569034.055 51881183.41 9.1174 12820 2 681635.461 57133864.73 8.3819 14118 0.998816 570108.553 57066214.23 10.0097 14101 3 738769.326 62847251.21 8.5070 15530 0.998997 572501.946 62784212.6 10.9666 15514 4 801616.577 69131976.33 8.6241 17083 0.999418 577001.417 69091740.99 11.9743 17073 5 870748.553 76045173.96 --- 18791 0.999744 581227.094 76025680.41 --- 18786 ... View more

Thanks. That seems to work for one iteration. What I need to do is show the increase of invasive weeds that are spreading at the rate of 10% a year, 5 and 10 years out. So I would have to run it 5 and 10 times, using the area and length from each iteration as the input for the next. Even putting the calculations into a script, that still leaves a lot of intermediate datasets to get rid of. What I did was to abstract the weed polygon into a circle, calculating the radius from the shape_area using the formula area = pi x radius squared. Then calculate the area of the 5 and 10 year circles using the formula = * 1 +( ) and calculate the radius of the new area circle. The buffer distance is then radius-new minus radius-original. I did try your formula on my circles modifying it to (( * 1.1[Number of years])- )/ but that resulted in a larger circle than I got from my original method. The Increase Polygon Area tool in the Production Mapping toolset will give you a polygon with a slightly larger area than specified, but it involves a lot of trial and error, and doesn’t work well on large, irregular polygons. Dave Stockdale GIS Program Manager Forest Service Sawtooth National Forest, Supervisor's Office p: 208-737-3278 f: 208-737-3236 drstockdale@fs.fed.us<mailto:drstockdale@fs.fed.us> 2647 Kimberly Road East Twin Falls, ID 83301 www.fs.fed.us<http://www.fs.fed.us/> <http://usda.gov/>[Forest Service Twitter]<https://twitter.com/forestservice>[USDA Facebook]<https://www.facebook.com/pages/US-Forest-Service/1431984283714112> Caring for the land and serving people ... View more

Thanks gentlemen, I will try these. ... View more

Thank you. I figured it had to do with HTML (which I'm not very good at). ... View more

You might try something like this: import arcpy,os wksp = # your SDE connection arcpy.env.workspace = wksp output = # your output geodatabase or folder fc = # feature class to convert base = os.path.basename(fc) b = base.split(".")  # splits on the periods b1 = len(b) b2= b[b1 - 1] # gets the last string which should be the name you want) arcpy.FeatureClassToFeatureClass_conversion(fc,output,b2) ... View more