RTC360 periodical wave-like noise

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Surdjak
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RTC360 periodical wave-like noise

Post by Surdjak »

Hi,

I recently began working on several point clouds acquired with a RTC360 that I need to remesh among other things. Problem is, the point clouds have some wave-like noises like this:

Image

Image

Here's the result:

Image

So my questions are:
  • Is that noise something that appear frequently in RTC360 scans ?
  • What could be the cause of that noise ?
  • Is there a way to remove that noise or to prevent it from appearing ?
Thanks in advance for your answers.

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Re: RTC360 periodical wave-like noise

Post by Scott.Warren »

Off the cuff it looks like you are seeing some data from a scan that is likely far from data taken closer to the camera view. The stripes you see are likely due to point spacing at longer ranges. the data points will be spaced further apart as the get further from the scanner. They also will be affected by the angle of incidence.

1. noise is likely data taken at a longer range by the RTC360 (maybe not noise, just sparse data)
2. see 1.
3. You can filter scan data by range in cyclone from with the "scanworld explorer" ex: delete points more than 200' from the scan location that acquired them.

4. the last image to me looks like a registration issue, where 2 sets of data are meeting. If this image is from a single scan, i'd worry. If it is from a registration containing multiple scans, i would chalk it up to the registration needing tweaking.

5. Hot tip, the scanworld explorer window has an awesome little 'color by scan' button, where it will assign a unique color to each scanworld, helpful in determining where points are coming from. if you checked your view again with this tagged on, you might notice 2-3 different colors showing the data is coming from multiple scan locations.

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Re: RTC360 periodical wave-like noise

Post by Surdjak »

Not sure about the exact distances but I think that's somewhere around 7 to 9m away from the base, is that considered far?

I'm already doing some kind of decimation by removing points based on their angle of incidence and distance and it's indeed removing some noise, but not completely.

There's indeed multiple scan datas, but in most places the decimation get rid of those meeting places. I'll still look into it though

Thanks !

EDIT: Could periodical vibrations could provoke this? (Like motors in a machine room or the scanner motor itself)

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Re: RTC360 periodical wave-like noise

Post by charles_nock »

Hi,

I have been seeing some odd data from my RTC360 when scanning objects at close range -- confirmed with a second borrowed RTC360, so not an oddity. Here an example image, from my backyard where a tree branch is < 5 m from the scanner and one sees "wavy" patterns in the returns. I'm not sure why as of yet but would be interested in opinions. Note: conditions were very still so this is not wind or movement. I also suspect it is more prevalent when the object, in this branches, are near the zenith.
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Re: RTC360 periodical wave-like noise

Post by KMack »

I am also noticing this in a 3DR cloud to cloud comparison at the surrounding area for each RTC scan setup in the comparison cloud. Any further thoughts on this? Does it perhaps indicate the scanner may need to be calibrated?
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Re: RTC360 periodical wave-like noise

Post by stevenramsey »

From that second image it looks like you have a registration error as you can see that one are in shadow looks fine then you have 2 other scans coming from different locations showing the wave from a much further distance. how tall was the tripod.
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