Georeferece

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SpaceMan
Posts: 4
Joined: Wed Apr 05, 2017 10:40 am

Georeferece

Post by SpaceMan »

Greetings,
When i Georeference a model using 6-8 known points and a cloud something beyond my knowledge happens.
It seems that it "cuts" the points and make sections.
This is very annoying because it seems that all the points on the edges "stack themselves together vertically.

Could someone please help me with this and guide me towards a smooth model without the gaps?

I`ve attached one picture that shows the issue
Best regards Jonas
daniel
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Re: Georeferece

Post by daniel »

Could you post a snapshot of what you see (before and after maybe)?
Daniel, CloudCompare admin
SpaceMan
Posts: 4
Joined: Wed Apr 05, 2017 10:40 am

Re: Georeferece

Post by SpaceMan »

daniel
Site Admin
Posts: 7712
Joined: Wed Oct 13, 2010 7:34 am
Location: Grenoble, France
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Re: Georeferece

Post by daniel »

This is clearly an issue with numerical accuracy.

Have you input the georeferencing points manually or have you loaded them as a cloud? Because you have to rely on the 'Global shift & scale' mechanism to avoid losing accuracy. So in the second case you have to accept to shift the points when loading them (the georeferenced coordinates will be restored when you'll save the cloud).

Be sure also to use a version not too old (i.e. 2.7 or later).

If it still doesn't work, don't hesitate to describe your process in details here, or even send me the file with the georeferencing points (cloudcompare [at] danielgm.net) and I'll try on my side.
Daniel, CloudCompare admin
SpaceMan
Posts: 4
Joined: Wed Apr 05, 2017 10:40 am

Re: Georeferece

Post by SpaceMan »

Hi again,

i`am brutally new to Cloud Compare and point cluds in general, could you please explain a bit further on the two cases?
I am using quite big coordinates witg 7 digits in northing and 6 digits in easting.
And i am manually inputting the measured points yes:)

Do i scale the coordinates down and re-scale them when done with the alignment?
What happens with the accuracy then?

Appreciate your help by the way!

Cheers!
daniel
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Joined: Wed Oct 13, 2010 7:34 am
Location: Grenoble, France
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Re: Georeferece

Post by daniel »

Hum, if you do it with manual input, you shouldn't need to do anything... CC should handle it properly (well in the other case as well - see https://www.youtube.com/watch?v=_eG-oj22YrY - but in this case you must be sure to apply the global shift when you laod the georeferenced points).

Does CC ask anything about 'global shift' during your process? And what version are you using exactly?
Daniel, CloudCompare admin
SpaceMan
Posts: 4
Joined: Wed Apr 05, 2017 10:40 am

Re: Georeferece

Post by SpaceMan »

Hi Daniel,

sorry 4 late answer , eastern holidays here in Norway.

But anyway, your last reply explained everything perfectly, and the issue is now solved.
So thanx a lot for quick reply.

Cheers , Jonas
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