Volume vertices

PIX4Dmapper PIX4Dmapper Questions/Troubleshooting
1

Hi all, im having issues computing a volume of a stockpile that is stored against a batter which is also on a radius. ive tried playing around with the different options for lowest point, triangulated, fit plane etc… however because i dont have a terrain model and measurements of the site before the stockpile was formed, i cant get a accurate calculation.

Its hard to explain so hopefully you can picture what i mean from these pics…

this was triangulated but it doesnt follow the batter and radius of what would be under the stockpile (obviously since it cant see it)

if i use lowest point i get the closest result. most of the base of the stockpile is flat and level with the rest of the site, however because its “lowest level” it doest follow the batter and toe of batter.

What i trierd to do but cant is build the surface to a rough model. (i know it wont be accurate but it will give a better measure than without. ive crudly drawn on in blue how i would be attempting to build surface panels… with the red being the normal ground level with the rest of the site. for the purposes of being able to see better i assigned the points of the stockpile to “temp hidded” when in the pointcloud editor. in the hope of when i showed the hidden elements and reoptomised then the volume calculation would also follow my added in surfaces.

 

Im at a total loss of how to explain this ay better, but i can certainly make all the images and files avalible via a dropbox link if someone wants them to see better what i mean.

2

Hi Kevin,

Thank you for the detailed description. I believe that I understood it and that we are on the same page. Well, at least I hope so (:

The scenario you are facing is quite difficult and there is no straightforward solution on how to calculate the volume of this specific stockpile. 

It might be possible to get an estimation of the volume if you divide it into two part, the volume until the base of the batter (1), and the volume from the base of the batter to the top of it (2). The volumes should be calculated separately and then summed together to get the full volume. 

The tricky part is that the base of the batter needs to be estimated and drawn on the top of the stockpile (blue line) and later on manually shifted to match the actual height of the base of the batter (curved yellow/red dotted line).

In this case, the same curved yellow/red dotted line should be used for calculating both volumes and the “Triangulated” option should be selected in the Volume Settings. 

The z-value of vertices can be manually changed following this workaround:

  1. Draw the outline of the volume in Volumes module. Make sure to define the horizontal footprint of your stockpile correctly.
  2. Edit the height of the vertices in rayCloud. When the volume is drawn vertices are created as MTPs. These MTPs can be modified to 3D GCPs (Ground Control Points) in the rayCloud view. This enables you to give specific coordinates to each point (z), e.g. based on a previous survey of the area or as a height of the surrounding area.  
  3. Close and reopen the project.
  4. Go to Volumes module, use Triangulated (default) processing option and calculate the volume.

I understand that the procedure will not give the exact volume and that there are some estimations that need to be taken into account (position and height of the base), but I believe that it is worth giving it a try as the exact base of the batter is not known at this point. 

Let me know how it goes, 

3

Hi Blaz,

Thank you, that is exactly what i was looking for. Excellent help.

Kevin