Student needs help - residual error and overlap

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snobbias
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Student needs help - residual error and overlap

Post by snobbias »

Hi people!

Just a short introduction. I'm studying to become a surveyor in Sweden and I'm almost done. However, first I have to write an essay and I decided to got for a point cloud scan I made in a cave. I will try to explain how to link projects together into one big point cloud through registering in TBC

Now, the process is more or less automatic as long as I give TBC a couple of common points. However, in this essay I need to go slightly deeper and give some more technical info. TBC doesn't tell me much, apart from "residual error" and "overlap", but I think that is enough. The problem is: I don't know what these mean.

I've tried to search for information, but the explanations are at a too advanced level for me (and for my essay). I'm just wondering if someone is willing to give me a simplified explanation of these two parameters.

Note: I would like to use Realworks but I wasn't able to get a hold of a license so I have to stick to TBC.
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Re: Student needs help - residual error and overlap

Post by MajorDomo »

Hello and welcome.

Use the search function, Daniel Wujanz posted some great write-ups that might be what you're after.
Use the keyword taming errors

This is a grossly oversimplified explanation:
Overlap = how much of a scan, or group of scans can be seen from a different scan. The commonality between these allows ICP algorithms to find the solution to register different scans together.
Residual = How far those points that are in the overlap region deviate from the ideal placement to achieve a perfect registration.

All things being equal, the more overlap you have, the lower the residual value, again, grossly over simplifying this.
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Daniel Wujanz
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Re: Student needs help - residual error and overlap

Post by Daniel Wujanz »

Dear Snobbias,

as Domo mentioned (thanks for that), here are the links to the articles in question. If you need more scientific explanations or have deeper questions, just send me a pm.

https://www.linkedin.com/pulse/taming-e ... ap-wujanz/
https://www.linkedin.com/pulse/taming-e ... el-wujanz/

All the best

Daniel
snobbias
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Re: Student needs help - residual error and overlap

Post by snobbias »

Thank you both for your help. I actually came across "Taming errors" a few weeks ago and I haven't been able to find any deeper analysis of residual error as of yet. The problem is I lack the knowledge to understand your articles. I will however reference them in my essay for those who are interested in going deeper.

@MajorDomo, your definition is fine for me.
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Re: Student needs help - residual error and overlap

Post by Daniel Wujanz »

If you are not sure how to interpret something, you can also simply ask. I will send you my email address in a pm.

Cheers

Daniel
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