Forum

Author Topic: Tie points and memory usage  (Read 1715 times)

FredR

  • Guest
Tie points and memory usage
« on: September 18, 2018, 08:05:22 AM »
Hello!
Is it correct to assume that the number of tie points determine the amount of memory needed to build mesh, more than the number of photos ?
I can build a mesh with 163 cameras and 112870 tie points but  have not enough memory to build a mesh with 124 cameras and 282944 tie points ?
Thank you for your answer!

Alexey Pasumansky

  • Agisoft Technical Support
  • Hero Member
  • *****
  • Posts: 14813
    • View Profile
Re: Tie points and memory usage
« Reply #1 on: September 18, 2018, 08:02:45 PM »
Hello FredR,

If you are building mesh from the dense point cloud, then the main factor that effect on the memory consumption is number of points in the dense cloud.
For the experimental (visibility consistent) mesh generation method the quality used for the depth maps is important.
Additional factors are: working volume (i.e. bounding box size) and complexity of the model shape.
Best regards,
Alexey Pasumansky,
Agisoft LLC

FredR

  • Guest
Re: Tie points and memory usage
« Reply #2 on: September 19, 2018, 07:12:03 AM »
Hello Alexey,
Thank you for your answer.
So with the experimental mesh generation method, the main factors regarding memory usage is the number of tie points and the quality used to build mesh ? (regardless of the working volume and the complexity of the model shape)

Alexey Pasumansky

  • Agisoft Technical Support
  • Hero Member
  • *****
  • Posts: 14813
    • View Profile
Re: Tie points and memory usage
« Reply #3 on: September 19, 2018, 08:35:02 PM »
Hello FredR,

Number of tie points practically does not have much influence on the mesh and dense cloud generation stages, as tie points are only used to identify, which pairs of images are overlapping and to estimate the general depth limits of the scene/object.
Best regards,
Alexey Pasumansky,
Agisoft LLC

FredR

  • Guest
Re: Tie points and memory usage
« Reply #4 on: September 20, 2018, 04:37:03 PM »
Hello Alexey,

Does it mean that removing points from the sparse cloud, especially those in the bounding box, will have no effect on memory consumption in the subsequent stages (dense cloud and mesh building) ?
By the way is there any good reason to remove points from the sparse cloud ?

Thank you!

SB

  • Newbie
  • *
  • Posts: 39
    • View Profile
Re: Tie points and memory usage
« Reply #5 on: September 26, 2018, 06:56:52 PM »
The good reason is to remove points with lots of error so that camera optimization will be effective.  I also remove noisy points to help me find alignment errors that will be easy to see in the dense point cloud, but without waiting to create the dense cloud.

Any problem you can find in the alignment before generating the dense cloud will save you a whole lot of time.

FredR

  • Guest
Re: Tie points and memory usage
« Reply #6 on: September 27, 2018, 07:37:11 AM »
Thank you for your answer SB.

I am not sure to understand how removing noisy points from the sparse cloud helps you find alignment errors. Can you elaborate on that ? How do you proceed ?

Again then you, it helps me a lot!