3D Area Measurement


I am trying to calculate square footage of grass matting on slopes. The Area tool reports the 2D measurement. Same thing for the Volume tool. Workaround is to use the distance tool to get the hypotenuse and add a percentage to the area value.



The cosine error is less than 10% for slope angles up to 25 degrees (area on slope = flat area/cosine of slope angle). 25 degrees is already 46% grade. The error falls below 5% for 17 degree slope (30% grade). So you could compute a few angles and quickly get a 1-3% accurate number for many cases I suspect.



Thanks Terry. I appreciate the information, but it not as easy or quick as you might think. I am dealing with varied slopes from 15-60%, in multiple configurations and even some compound slopes, ditches and berms. As you can see I already have 17 intricate areas and I am not even halfway through the job.The total to this point is over 5 acres.

I know the percentages as related to the rise/fall on automatic recall as i have been doing this math for years, but it still requires documentation of the individual slopes, exporting to excel, assigning the slope values, sorting and calculating the sums of the function. We were able to accomplish the reporting of the slope on the line done so I think this would be achievable.


Manipulating the Area measurement tool is hard enough…

It would be nice to have exclusion areas too.



Good thing you get paid. You earn it.

I think I could program this up in Rhino using the 3D model with my 3D slope map and your overlay (best if it could be line data with coordinates). Then I could grid each region and sum the slope-adjusted grid areas to get a total or per region. Can’t this be done in that Carlson tool you use or does it not have a programming interface?