3D Targets geometry position

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asked Mar 15, 2016 by kelbers (120 points)
Hi, I generated a 3D target and tested it on a photo. The 3D model I generated with 123catch. It is shown correctly in the viewer in the target generator ( its just  flickering a lot ). During the test with the app the geometry and the pointcloud show up, but in a very different position than the real object on the photo. The tracking seems to work though. Is that how its meant to be or should the 3D geometry be exactly in the same position as the real object after the target is generated? If it should be in the same position, what can I do to make that happen?

Thanks and Regards, Kai

1 Answer

0 votes
answered Mar 15, 2016 by Alex (6,680 points)

Hi,

as far as I understand the flickering issue you are having is in your Internet browser, am I right? If this is the case the problem is related to the fact that you are using the OBJ exported by 123D Catch but, quite often, the normals of this kind of meshes are flipped and you should reverse them before uploading.

 

Also, before uploading the reconstructed mesh, it is strongly advisable to always import it inside a 3D editing softare in order to:

 

  1. remove noise and un-necessary surfaces and eventually flip the normals
     
  2. transform the mesh in such a way that it is oriented and scaled correctly (this is really important also because you will be able to add any augmented content on top of the tranformed mesh in the 3D editing software and when you will load it in your app it will be exactly where you expect it to be)


 
If you follow the above steps, the 3D geometry should be exactly where the real object is, otherwise something went wrong during the target creation process.

 

Can you confirm that not only the 3D geometry but also the pointcloud is in a wrong position? If this is the case can you send a screenshot? Does it look rotated by 90 degrees or is it in a totally different position with respect to the real object?

 

By the way, another important factor to keep in mind is that you MUST use the ARMedia Toolset app to take pictures of the object you want to track, please refer to this question for details:

 

http://dev.inglobetechnologies.com/helpdesk/index.php?qa=899&qa_1=how-to-take-pictures-of-object-to-create-good-tracking-target


Alex

commented Mar 17, 2016 by kelbers (120 points)
Hi Alex,

thanks for the quick response. I didnt use the AR Media Toolset for the pictures. I used the photos from 123DCatch. So that might be the issue. I did it because the Toolset App didnt create a folder with photos on my Z1 Xperia Compact. Therefore I took the photos from 123DCatch and made them smaller, so that they pass the upload check ( I think your required size for upload is less than 1024px ).

I also tried a Nexus7 now for making the pictures with ARSDKmediaToolset. On this device I cant find the ARMedia Folders at all although the app is installed and when I make the pictures with it, it says that the images were saved to the specific folder. Do you know about that issue?

If I still have issues with the Toolset App, can I use the 123DCatch photos in size 640*480px?

The flickering of the 3D Model in the browser still exists with flipped normals.

Regards, Kai
commented Mar 17, 2016 by kelbers (120 points)
Update: I found out, that when I capture photos with the app and then restart my Android device, wait for about two minutes, the folder with the images will show up. I dont know if this issue is maybe windows related...I am working on Windows 7 Pro.
commented Mar 21, 2016 by kelbers (120 points)
Hi Alex,

I did the entire Target creation now with the photos from the app. The target works. The pointcloud seems to be in the right spot but the 3D Model from 123DCatch is still not in the correct position. In your post you mentioned to "transform the mesh in such a way that it is oriented and scaled correctly...".
How exactly can I do that? How can I find out where the 3D Model is in the right spot. The only information I have is the pointcloud generated by the target creator right?

Thanks in advance, Kai
commented Mar 21, 2016 by Alex (6,680 points)
Hi Kai,
when I say to "transform the mesh in such a way that it is oriented and scaled correctly..." I just mean to align it in a convenient way and to scale it reasonably, because usually the mesh that is reconstructed is rotated in an arbitrary way and usually is bigger or smaller than the real object... so you should use Blender to move the mesh around the origin, scale it in such a way that it makes sense (a car should be more or less 4 meters long, a toy could be 20 cm high, ...) and rotate it in such a way that horizontal surfaces are parallel to the ground...

When you say "The pointcloud seems to be in the right spot but the 3D Model from 123DCatch is still not in the correct position" are you talking about Blender or Toolset app?

Alex
commented Mar 22, 2016 by kelbers (120 points)
Hi Alex,

it worked now. I could import the 3D model and the .ply file in Blender. Than I rotated the 3D model so that it fits the pointcloud. I didnt do scaling. It seems the scale is quite ok for our purposes.
The pointcloud was in the right position when I used the toolset app.
Thanks a lot...
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