Forum

Author Topic: Dense Point Cloud Upper Limit?  (Read 5114 times)

driftertravel

  • Newbie
  • *
  • Posts: 46
    • View Profile
Dense Point Cloud Upper Limit?
« on: April 27, 2015, 05:10:53 AM »
Hello all, I'm currently working on a project that will involve 3-4 thousand photos, preferably processed at high quality, I can process in chunks, but I'm curious about when I go to merge the dense point clouds... I've got 128gb ram, but I'm wondering if anyone has an idea of where the upper limit of the size of the point cloud lies... I'm thinking I can generate a mesh in another program so I don't have to worry about running out of ram there, but I'm hoping I can get a quality point cloud of the whole thing to export... Any thoughts?

Marcel

  • Sr. Member
  • ****
  • Posts: 309
    • View Profile
Re: Dense Point Cloud Upper Limit?
« Reply #1 on: April 27, 2015, 11:14:04 AM »
We haven't run into any limits yet, I think our biggest scan was over 2 billion (2000 million) points and I have read forum posts of users who went even higher.

If you process such a big scan in one go, then memory can be an issue even for the DC stage (normally the DC stage doesn't need that much memory). This also depends on the nature of the scan, a scan of a terrain (photos in a grid pattern) will take less memory than a complex 3D object.

My advice would be to process the Dens Cloud at Medium first and see if that gives you the detail you need. Because if you process it at High or Ultra and you end up with a point cloud that is un-workable due to the size, then you have wasted many hours of processing (since there is no way to reduce the point cloud at this point).

If do you find a program that can mesh such very dense point clouds then please let us know.  8)



driftertravel

  • Newbie
  • *
  • Posts: 46
    • View Profile
Re: Dense Point Cloud Upper Limit?
« Reply #2 on: April 27, 2015, 04:17:31 PM »
If do you find a program that can mesh such very dense point clouds then please let us know.  8)

I was going to give geomagic wrap a go, as it's designed to handle a butt-ton of laser scanning data at once. I think a lot of these programs that deal with large dense point clouds do a number of things that photoscan, for all it's greatness, just can't do: 1st, they can mesh pretty large models, 2nd They have some more advanced tools for cleaning up point clouds and 3rd a few of them seem to switch between dense cloud when you are looking at things from a single vantage point and a sparse cloud when you're moving around, so things don't get so bogged down... If anyone has any experience with any of these tools I'd be excited to hear about it. On the other hand, I think 2 billion points will probably do the trick, thanks! :)

igor73

  • Full Member
  • ***
  • Posts: 228
    • View Profile
Re: Dense Point Cloud Upper Limit?
« Reply #3 on: April 29, 2015, 02:42:09 PM »
Also interested in opinions on external sw for mesh generation as Agisoft is a memory hog at that stage.   

As marcel said dc stage is not that memory intensive so you may be just fine with high setting. I would definitely run a large project like this om medium though as when you get  to mesh stage you are going to need massive nr of chunks.  Run a sample at medium and high and compare the results.  Often the difference is very small and in some cases medium can help fill holes and actually give better results.  It all depends on the image quality i think.  For high you need good image quality. 

  I ran a project using 4000 36 mpix images on medium dc setting on a 64GB ram system and it was no problem at all.  For Mesh generation i had to split in to 5 chunks though.