Hi there,
What is the best way to deal with reflective water surfaces? In my map there was a small lake. (I am second guessing the outcome here)
Thanks!
Hello,
It is indeed difficult to calibrate the images that capture only water since it is very hard to find keypoints on water surfaces and even if keypoints_ are found, it is very hard to match them between images. _
I suggest taking images that contain water with some land (30% of land minimum) so that the images will get calibrated and contribute to the orthomosaic generation.
Check this article for more info: 202557459.
Best regards,
Hello,
I´m working on a survey of an open pit mine, that has a lake inside. As you know, that water is an issue for photogrammetry, so I tried the surface option. However, the borders of the lake is full of bush, and I can´t have a constant elevation on the MTP. If I put too much on the water, is not reliable due the erratic points created. If I put on land, I touch the top of the bush cannopy, so is also erratic and not constant the elevation. I can´t edit the Z value of each MTP, I can´t import any shp file… in fact this is a tool too limited to solve the challenge of the water in photogrammetry, what is even worse, as if we know in advance that this one the biggest downside of the photogrammetry against other methods, like LIDAR, I was expecting a better solution to answer to this need.
Please, how can I sort this out, creating the surface of the water with a constant elevation?
…and I know that this not possible at the moment, but will be great if in a future release, we can define a surface that can be mandatory to the point cloud, and will push the points to adjust to that specific elevation, and doing so, we can use and export the full point cloud, instead playing around with the erratic points and putting them into the disable group.
Thank you,
Regards
Nuno Santos
Hey Nuno,
Very interesting use case. Thank you for sharing it with us.
At the moment, I don’t think it is possible to import surfaces in the software. As you said, you would have to create them directly in the software and edit each MTP separately.
I will pass it on to our product development team for review for future releases.
I’m having a similar problem, and I KNOW this user community and the intelligent people at Pix4D who provide service to them can figure it out (and may already HAVE: if so, my apologies for a stupid question and my many thanks in advance for pointing me in the right direction).
So the problem is this: I have dark water areas associated with my projects. They tend to generate in 3D as boiling surfaces. I’m guessing this is an artifact caused by reflections of clouds or something.
How do I resolve this? As with Nuno above, my edges are typically bush and erratic, with overhanging vegetation. Can I flatten the water out? Can I import a SHP file mask from ArcGIS such that the model is created with a planar surface that looks sort of smoky brown and translucent, like the water captured in some of images? Can I pick an exemplary sample from the imagery?
Please help me out here folks. These artifacts are distracting to my audience, and it takes their attention away from the subject they are supposed to be viewing.
Kindest regards,
- beel
HI @UAV_Program,
We would to need to have a look a on your Quality Report to check your processing options.
Water surface are also difficult to reconstruct since they are very homogeneous which makes finding matches more difficult. This tends to lead to noisy point clouds as you are describing it.
Few advice:
Reduce the image scale of the first processing step.
Reduce the number of matches:
Cleaning the point cloud:
Which output are you displaying? Point Cloud or Mesh?
For the mesh, you can improve its quality by adding a surface that will used to flatten a water surface for example:
These recommendations should help.
Best