Different versions of .obj file format?

[vdH]

Hi guys. I’ve been using a Shining DS EX to scan and then I import the resulting .obj (with texture) into a tray design program (Shera easybase).

Recently the shining scan software got updated, and the design program refused to load.

The supplier on the design side said he thought the files looked corrupted even!

I had a quick look and the headers of the old .obj, and the new obj. are totally different. Also, now in the export folder there is a .png with the texture data. That wasn’t the case with the old version (I’m guessing the texture data used to be embedded.)

Meshmixer and exocad can open them, but I haven’t found a way to export the new files to a format that Easybase can read. It can read the .ply without texture but I need that for my workflow to work.

So my question is, does anyone know if there’s been a change in the .obj file format. Should an .obj always have the texture data embedded? And of course if anyone has a solution, I would be much obliged.

 

[erzdaemon]

nearly same Problem with partially solution here > https://dentallabnetwork.com/forums/threads/texture-manipulation-for-ply-files.34454/

 

[Davalier]

You can open your files in exocad and save them in other format like .stl

 

[erzdaemon]

Hi Davalier,

yesssss, with this additional export ( on top of meshlab texture to vertex, export as non-binary ) it works!!! I am gonna explain in Detail in my original thread here > https://dentallabnetwork.com/forums/threads/texture-manipulation-for-ply-files.34454/

Thank you so much guys

 

[erzdaemon]

So here's my "Final" Solution:

1. Open the File with the seperate Texture file (jpg in my case) in Meshlab
2. Filters > Textures > Transfer Texture to Vertex Colour
3. File > Export Mesh as... > standard polygon format file ( ply )
4. In the following saving options disable "binary encoding" and disable "texcoord", not sure if this is mandatory
5. Import this file as Jaw Scan into a random created Exocad case and use the save as method as shown by Davalier here https://dentallabnetwork.com/forums/threads/different-versions-of-obj-file-format.33670/ ( chose ply as filetype )
6. Final PLY can be imported into shera easy base with colour then

 

[Jussi Roivanen]

Pure .obj (wavefront obj) is set of text (ascii) instructions that define how to draw a shape. It does not contain texture/material/color information. Separate Material file (.mtl, wavefront material) can be associated with .obj but it does not support bitmaps (jpg/png),it deals with certain mapped texture files.

Binary obj is, as far as i know, line-by-line string conversion to zeroes and ones, to binary format (using ascii tables).

There can be Vendor (software) Specific Extensions in .obj. In theory can be used to store object color (even in ascii format quite easily) and even if binary format is used, those extensions can be used to embed texture (since jpg/png are images, which are binaries). Vendor specific extensions are, and should be, ignored by other programs since it is virtually impossible to know how those instructions should be interpeted.

erzdaemons solution is solid: open obj in program that can handle textures as well, map textures and then export with format (like ply) which actually supports textures/materials.

 

[tuyere]

Just for the record, by far the best CAD program for opening any mesh and exporting to any mesh format that I've used is Rhino 3D. Not dental-specific, and it has a learning curve to use its more powerful modelling tools, but very good for editing, repairing and modifying meshes of any sort. It opens pretty much any mesh file, no matter how gnarly or corrupted, and can export very cleanly as whatever you need. Very lightweight and zippy software, too.
A lifetime license is, like, $600 or so? Not worth it just for file conversion, but phenomenal value as a mesh CAD platform goes, and maybe worth it if you find yourself repairing and editing scans a lot and often find the built-in dental tools lacking or not giving you enough control. The developers are also very nice guys and offer extremely generous trial terms + they refuse to implement any inconvenient piracy protection, it feels good to give them some money once you've used it for free for the *90-day* trial period.

 

[erzdaemon]

Hello again,

on further inspection, the real source of the Problem seems to be, that 3Shape uses different filenames for the exported .ply and texture .jpg ( e.g. replacing "_" and "space" in filename).

If you rename both .ply and .jpg to be the same, you might be able to import correctly.

Real Solution however should be, that the Software Devs ( Shera, R2deusexmachina etc. ) use the Filename for the Texture-File which is in the Fileheader of the .Ply in Plain text.

cheers

 

[vdH]

Hi, i thought I'd reply to my own thread for posterity's sake.

Ive never been able to either export from exocad as a compatible file, or us meshmixer to create something..

HOWEVER:

The latest Shining update has a "Digistell" (French CAD program, from a more ortho focused dev) export preset. Combined with .ply filetype, this works in Easybase! If erzdaemon could check with Bitereg, that would be awesome. Im guessing Easybase is from the same developer originally. Just a hunch based on some circumstantial evidence.
Still having difficulty with Zirkonzahn and Shining, but thats not a huge brand here and those labs are mostly 3Shape based. It would be interesting to know if someone else has made that work, as Formlabs did promote it for designing trays for their printers. Formlabs guys are more likely to have a Shining scanner I would guess.