Generate normals for ascii pointcloud

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mls
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Generate normals for ascii pointcloud

Post by mls »

Hi Forum.
I have some very noisy sonar data and I am looking for a way to add normals to the points so I can edge light/shade it in Pointools. This will help in visual interpretation for an animated flythrough.
The import option in POD creator has a generate normals option, but this does not seem to apply to ascii import.
If anyone has any ideas please let me know.
Cheers
Paul
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Re: Generate normals for ascii pointcloud

Post by jcoco3 »

Hi Paul,

Interesting problem and first mention of sonar I have seen. The only way I know how to do this is using pcl in CloudCompare, but there must be other ways. I am very interested in how you end up solving this problem. I know so little about generating normals, maybe one of the experts here can enlighten us. I know Recap uses normals for on-screen rendering of the point cloud, but I don't recall if it generates or just imports the normal.

Sorry I could not be more help :(
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Re: Generate normals for ascii pointcloud

Post by tbwester »

I don't know if this would work, but I would try importing without normal's - then exporting in another format - then importing that format with normal's.

I don't think you need anything more than xyz points in order to generate normal's, but I could be wrong - and like Johnathan - I don't know much about the methodology behind their creation.
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Re: Generate normals for ascii pointcloud

Post by dwayne-ellis »

This can be done using Meshlab. If i get some time in the next day or so i can whip up a video tutorial.
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Re: Generate normals for ascii pointcloud

Post by mls »

Thanks everyone.
This problem stems from my stuborn intention to get some lighting (edge lighting) effects in a Pointools flythrough aniamtion.
The data is VERY noisy, and will not even lend itself to meshing.
The meshlab solution sounds interesting - looking forward to the mini tutorial.
There is also a method using Geomagic Studio, and also one using Rapidform XOR, where normals can be added to an ascii pointcloud after it has been imported. I cant find a way of getting the data back into Pointools though. PTX export from either of these apps might work. I also tried creating a "synthetic" FARO fls file by importing the ascii into faro scene.
Cheers
Paul
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Re: Generate normals for ascii pointcloud

Post by Mark Christy »

Hi Paul,

Pardon the blatant "advertising", but I think your problem may be a perfect test bed for us.. so we may be able to help each other out?

We're about to release our new version of Arena4D and one of it's new features is a real time dynamic lighting capability, without the need for normals in your data. The lighting occurs in real time at run time and you don't need to do any processing of your point cloud apart form import it into Arena. You can then produce HD video very quickly from Arena, therefore killing two birds with one stone.

We've tested the technology with all kinds of point clouds and it makes a remarkable difference with highlighting the slightest details. It would be interesting to see how it works with Sonar....

I've put together a very quick video straight out of Arena showing the new lighting capability so you can see what it can do with a standard point cloud. If you'd like to see if we can do something with your Sonar data let me know, it'll be an interesting test!

[youtube]http://www.youtube.com/watch?v=OvLgwRNw ... e=youtu.be[/youtube]

Many Thanks

Mark
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Re: Generate normals for ascii pointcloud

Post by jedfrechette »

Mark Christy wrote:We're about to release our new version of Arena4D and one of it's new features is a real time dynamic lighting capability, without the need for normals in your data.
That looks quite nice, pretty similar to the Eye Dome Lighting in CloudCompare in that it is a little bit blurrier than with normals but is vastly superior to flat shading. Can the user control the specularity of the material shader? Your example looks a bit glossy for my tastes.
Jed
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Re: Generate normals for ascii pointcloud

Post by Mark Christy »

Hi Jed,

Yes, similar ideas. I think we've approached it from different angles (pardon the pun!) from my understanding of how Eye Dome Lighting works but the aim is the same and to provide depth to the image based on the information we can extract at render time.

Our approach does effectively reconstruct normals and therefore allow lighting and materials to be applied as per any other 3D geometry in the scene. The quick video was just a default light type, but the intention is to provide controls for ambient, specular, etc.. to get it how you like.

To be honest I've used it most without colour as it pulls out very small details not noticed before and the colours of the point cloud distract from subtle changes in the data.. so more of an an analysis tool than for out and out realism.

However this is going off topic a little and I don't want to derail Paul's thread!..

Many Thanks

Mark
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Re: Generate normals for ascii pointcloud

Post by jedfrechette »

Mark Christy wrote:To be honest I've used it most without colour as it pulls out very small details not noticed before and the colours of the point cloud distract from subtle changes in the data.. so more of an an analysis tool than for out and out realism.
Yeah, that's what I spend most of my time looking at too and definitely where a decent shading model is needed most. Does Arena4D have a demo?

Back on topic, its been awhile since I've used Pointtools but can't you import a generic text that includes normals? A format something like:

x y z dx dy dz

If that's the case you could reconstruct normals in CloudCompare or Meshlab, export the text file and use that in Pointtools. I don't think using PTX will work as the normals are implicit and you would need to somehow reconstruct the original point topology from your ascii file.
Jed
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