Forum

Author Topic: dense point cloud only?  (Read 23258 times)

RalfH

  • Sr. Member
  • ****
  • Posts: 344
    • View Profile
Re: dense point cloud only?
« Reply #15 on: January 06, 2013, 03:58:04 PM »
hello pixel_Killer,

the standard version of PhotoScan applies an arbitrary scale (I assume the pro version does the same as long as no georeferencing information is given) which I don't know what it is based on. In Agisoft StereoScan, scaling appears to be based on the modelled camera-camera distance (which equals 1.0).

Alexey, can you provide some details here? Is the scale in PhotoScan based on camera to camera distances or camera-object distances or something else? Knowing this would be very useful in many cases.

I often had Meshlab crashing when using large files (even a few hundred MB); I hope they will improve this sometime soon.

 

pixel_Killer

  • Newbie
  • *
  • Posts: 7
    • View Profile
Re: dense point cloud only?
« Reply #16 on: January 08, 2013, 08:56:07 PM »
I haven't been able to do an extensive test on comparing high vs ultra calculations. But based on what I've seen, I can't justify calculating at ultra settings anymore. The program is very aggressive when it comes to creating polygons, even in exporting dense point cloud.

Maybe the ability to create additional proxy/bounding box around the sparse point cloud could help. To be able to specify the max point count per bounding box. That way your not opening a file to find out there is 600million points around and object that could of been visualized with just 1 million.
« Last Edit: January 08, 2013, 09:10:57 PM by pixel_Killer »

RalfH

  • Sr. Member
  • ****
  • Posts: 344
    • View Profile
Re: dense point cloud only?
« Reply #17 on: January 09, 2013, 12:07:09 PM »
Hello pixel_Killer,

I think I would prefer using the ultra setting and clean up the dense point cloud later. The reason is that in a few projects I have seen small step-like artefacts which occured under low, medium and high settings but disappeared under the ultra setting. But yes, you're right, how am I going to handle a 300 GB point cloud file?

A good idea (Alexey, are you reading this?) would be an additional option in the "export dense point cloud" feature where the user could specify not only the quality settings (low, medium, high, ultra) but also the maximum number of points (and perhaps yet another choice: select points by quality or by spatial coverage). Which reminds me that at some point I have seen a remark in this forum that it would be nice to also have a quality tag for every exported point.

Alexey Pasumansky

  • Agisoft Technical Support
  • Hero Member
  • *****
  • Posts: 14968
    • View Profile
Re: dense point cloud only?
« Reply #18 on: January 09, 2013, 02:12:06 PM »
Hello RalfH,

In case of no Ground Control information is applied in PhotoScan Pro the scale of scene is arbitrary (like in Standard edition). There is no straightforward formulas to calculate the scale based on initial parameters.

We will think about adding density settings in the Export points dialog. But meanwhile for aerial datasets we could advice to export DEM in XYZ-format, for example, since it is possible to specify the grid resolution of the exported DEM.
Best regards,
Alexey Pasumansky,
Agisoft LLC