Agisoft Metashape

Agisoft Metashape => General => Topic started by: SimonBrown on April 23, 2015, 09:56:09 AM

Title: Mesh area report with zero thickness - correct value?
Post by: SimonBrown on April 23, 2015, 09:56:09 AM
Good morning. I'm new here so I'm asking a newbie type question...

I have mapped an underwater shipwreck site and gone through the workflow in PhotoScanPro to derive what I think is a really good model:-

https://sketchfab.com/models/949b1f97922e4a239dfb60b31056ed62 (https://sketchfab.com/models/949b1f97922e4a239dfb60b31056ed62)

So in my model the mesh has zero thickness. Area and volume report 1622.59m2 and zero respectively.

But am I correct in thinking that 1622m2 is counting both sides of the mesh? To get the correct value of area of mesh a simple 1622/2=811m2 would give the value of a single side?

Based on my gut feeling about the size of the wreck site, I think yes...but always prefer to know rather than guess...

Secondly, I have generated a report for the model and one value has caught my eye:-

Coverage area: 0.00115897 sq km, or 1158.97m2

There is some variance between mesh area and coverage. I am guessing that the mesh includes any vertical (or angled) faces and coverage is a true projection? In other words, if you flattened the mesh out its area would be bigger than the area it covers. This would explain why the mesh area is greater than the coverage...but then raises doubts over mesh area being both sides...

I hope the above makes sense.
Title: Re: Mesh area report with zero thickness - correct value?
Post by: Alexey Pasumansky on April 23, 2015, 11:55:16 AM
Hello SimonBrown,

Area calculation tool in the Tools menu estimates the area of each polygon of the mesh model and sums them to get the final number, whereas the area value in the report provides only area in XY plane.
Title: Re: Mesh area report with zero thickness - correct value?
Post by: SimonBrown on April 23, 2015, 12:01:15 PM
Many thanks Alexey - thank you for confirming.