obj file and import a CT Dicom data

[Raghadfahhad]

Hi all, i am a new in term of using this software.
First, i reconstructed 3d model by photogrammetry techniques using Agisoft Metashape software. following 5 steps, add the photos from the desktop folder, align photos, build cloud density, build a mesh, scale the model and finally exported it as a obj file. these steps for the two model. so, when i import the two file to CloudcCompare to compare the two models, i cannot do the final registration which is an e Align (point pairs picking) and finish it. As well, all models comes in the same color, what do you think the problems for it. i cannot get one model with green and the other with gray color.
i was following this pagehttps://www.cloudcompare.org/doc/wiki/index.php ... D_entities but i am struggle with the Align (point pairs picking).
second point, can i compare two models one generate by ct scan and the other with photogrammetry. to clear the photogrammetry model generates on obj file but the ct scan i download it on zip of CT Dicom data.


regards
Raghad

[daniel]

CC doesn't manage DICOM data (you would have first to open the DICOM volume with another tool to create a mesh).

Otherwise, which version of CC are you using? The latest ones (2.10 and 2.11) allows to pick points on meshes easily, and using the 'Align' tool shouldn't be an issue (there are even some videos on Youtube that explains that).

And last, regarding your OBJ files coming without any color, have you checked if there's any warning message in the Console (F8). OBJ files generally come with texture files (jpg, png, etc.) and a 'mtl' file. They should be next to the obj file.

[Raghadfahhad]

Hi Danil and thanks so much,
i was convert the ct dicom file to a stl file and import it on the cloudcompare.
So, i would i ask you can i compare the 3d model that create by agisoft metashape involving these steps ( add photo, align photo, build cloud density, build a mesh, scale it and finally export itas obj file) to stl file of ct scan which is using as a gold reference) ?

what are the steps that i need to compare a 3d model to ct a mesh, could you please give me a link which helps me?
as well, it is need to scale the 3 d model by cloudcompare before i compare it with CT stl file?
regards

Raghad

[Raghadfahhad]

hi all,
when i am trying to Align (point pairs picking), it come with this error as the screen shot show.
i cannot align all the model just CT mesh.
regards
Raghad

[daniel]

To compare 2 meshes: see https://www.cloudcompare.org/doc/wiki/i ... comparison (and pay attention to the very last section)

Otherwise, which version of CC are you using? (note that it would be better to make screen captures of your screen (with the Snipping tool, or the "Print screen" key, or even the "ALT+Print screen " shortcut ;)

[Raghadfahhad]

Thanks Danil,
I have a problem, i followed the link that you sent but i got RMS is very big and when i make comput i got some not work. So, i would like to ask you what is the main problem for it. And i noted that when i open obj file which i created by Agisoft Metashape, in the costal it appear there is a problem with reading mtl material and texture can define. So do you think the problem becaues that ?? And what i have to do to get best result to my model??
And when i open ct obj file no problem with it just with the one which i created .
Regards
Raghad

[daniel]

So the distances computation should always work I guess, but it can take a very long time if you clouds/meshes are very far apart.

Which makes sense if you have a very big RMS (which either mean that the two meshes are very different, or that they were not correctly registered).

And last, for you obj file, the material and texture files should be next to the OBJ file to work. But if they are not, you'll just miss the textures (it won't impact the result or hinder the distances computation).

[Raghadfahhad]

thanks for a clear explanation.

regards