Moving objects

[Anonymous]

Dear all, 

I have been playing around with Recap 360 on the cloud for a while now trying to find the limits of what sort of projects it can be used on. I have come to two stumps with trying to model: 1) Modelling a roundabout whilst it is busy with cars 2) Modelling a footbridge spanning over water. On both I used photos from ground level with around 100 included. I know Recap doesn't work well with moving objects or reflective surfaces for obvious reasons but I wanted to test whether it can be combated using stitching points not including any of the moving objects or reflective surfaces. Unfortunately so far I have been unsuccessful and was wondering if anyone else has discovered ways round this? 

Many thanks,
Kieron 

[amorap · Accepted solution]

Hi from Spain, Kieron

Unfortunately, there is not a magic solution for eliminating moving objects. This have to be done by hand.
I only use ReCap with laser scanner files, then it is possible that what I will say below will not work for you if you do not use a scanner.

When I shoot over a reflective surface I do two things in order to minimize the work later.

1- In my scanner (faro focus x130) , I select the best precision that can be made. This mode take 8 shoots for each point and the scanner performs an average of them in order to obtain the best results.

2- In ReCap, usually very reflective points have low intensity values. Then it is possible to apply a filter by intensity when you are importing a new point cloud. Unfortunately, ReCap dose not allow selecting points by intensity unless you are just importing a new point cloud file. The workaround is export your current point cloud and re-import it in a new project.

Once we have already tried removing the junk points in this semi-automatic way, I have a few tricks

A)- use the "limit box" -> "pick" tool. This allows focus on a region or specific area surrounding the conflictive points, in order to do a better selection and erasing them.

B) I prefer to use a parallel projection view, not perspective, and set the proper orientation. Usually, the conflictive points are captured from vehicles, persons... then I think its better set the orientation to front, right... instead of top or an oblique view.

C) The process to select points and erase them must be done by hand. Use the proper tool in each case: window, fence or plane. My preference is the window beacuse is faster than the other two, and if the view orientation is good, then with a few windows the work is done.

Regards from Spain.

[berson.guillaume]

Hi,

I totally agree with Amorap's solution. Cleaning the point cloud manually takes time but it is worth it.

In addition to points A) B) and C) I would suggest to hide every scan location but one, erasing junk points, display another scan location, and so on. It will be very helpful when you have fake points taken through a mirror for instance, while there is actually a room on the other side of this mirror.

[amorap]

In my humble opinion, beware of this: it is possible that there are some overlapping points in the area that belong to other scans and could be invisible.
When we work with terrestrial laser scanner, we need to overlap each scan with others in order to register the whole point cloud.
Before erasing by hand, Its needed verify that no other scans having overlapping points in the area, because the work could be increased twice or three times. If only a scan is visible when we are doing cleaning work, its possible that when we turn on other scan locations, then we notice that there is a lot of work remaining to be done.

Regards from Spain.