NextPreviousHomeAbout reading OBJ files

aki | 5 months ago | 23 comments | 1 like | 786 views

julio solano likes this!

Hello everyone.
I made a model of an arrow in a blender.
I made this an OBJ file and read it with Blufftitler.
Then the wings of the arrow will not be read correctly.

Is there any mistake in the OBJ file I created?

Download media files (34.1 KB)

Share this on FacebookShare this on Twitter

I am usind blender first time. How add textures at to object model in blufftitler. ready I converted from fbx to obj for blufftitiler using the textures

julio solano, 5 months ago

When I double click on your OBJ file, it is opened in the Windows 3D Viewer app. This gives a similar result as in BluffTitler so I think there must be something strange with your model. Maybe modelling it differently can solve the issue.

michiel, 5 months ago

Ho aperto il file condiviso con Photoshop e salvato di nuovo come obj senza alcuna modifica . Non so perchè ma adesso la freccia si vede bene

nonnogio, 5 months ago

Open with accutrans and save again.
And add some textures.

Result in BT

It's a beautiful arrow! Thnx.

Filip, 5 months ago

The same thing happens to me too, if I open the file in BluffTitler I have the same defect.
If I open the file in AccuTrans 3D and always save it as obj it works fine. I looked at the arrow in Blender and saw that the tail has a solid that starts wide with 4 stitches and comes tight with stitches in common. It could be a problem related to normals, how surfaces are viewed

Franco Aversa, 5 months ago

I drew the end of the arrow myself.
As you can see I made some mistakes on the "normals" and BluffTitler no longer understands how the faces are oriented.
By loading the file into AccuTrans and re-saving it, the software orients the faces correctly. As you can see, Blufftitler also displays the drawing correctly.
I think it is a problem of Blender because especially with cut objects it can create confusion in the cuts. It had already happened to me with windows and doors that I had made with booleans.
The thing that can be done is to pay close attention to the orientation of the faces

Franco Aversa, 5 months ago

Thank you to everyone who responded.

I understand from the PiPPi test results that this issue is a blender characteristic.

I tried AccuTrans 3D from Franco and Filip's suggestions.
The result was good.

Some of the 3D models I own had similar issue issues. It was a 3D model created for a long time ago, so I didn't know the solution and left it as it was, but I was able to solve it.

For me, the $ 20 AccuTrans3D fee has become a worthwhile purchase.

Thanks to everyone, I was able to solve the issue where the OBJ file created by blender is not drawn properly by BluffTitler.

Thank you for your help.

aki, 5 months ago

We've taken a closer look at your model and found out that it contains concave polygons with 20 vertices. Especially the concave part is unusual. BluffTitler, Windows 3D viewer and most game engines assume that all polygons are convex. This greatly reduces loading time.

Your arrow shows that we can't assume this, so we will add a convex check in the next version of BluffTitler and properly triangulate concave faces. Thank you for the test model!

I don't know much about Blender, but this seems to be the modifier to fix your model for now:

michiel, 5 months ago

@Michiel  @PiPPi

I'm new to Blufftitler and at the same time I'm new to blender. I didn't intentionally make it a concave polygon. Basically, I created it based on a cube. I don't know why it became a concave polygon.

I have noticed using a blender.
It's Blufftitler is a very easy-to-use app.

Blender is free and seems to have many advanced features. But many small settings confuse me. In that respect, Blufftitler is very simple. Really easy to understand! (I haven't mastered it yet ...)

I think this community is as great as the ease of use of Blufftitler.

Thanks to Michiel and the many users who participate in this community.

aki, 5 months ago

michiel, could you expand on the issues with OBJ "polygons with holes" import into BT?

I created an OBJ that consists of a very basic polygon with zero height and a hole and it shows up fine in MeshLab, C4D and Blender but not BluffTitler. See image.

If that is what you're onto, I'd choose supporting holes in polygons.

As for OBJ load time, they are really excellent now. It's obviously very hard to know before the fact but in your estimate, what kind of load time increase would this "hole support" add in your, percentagewise?

PiPPi, 5 months ago

PiPPi, you've probably done something like the left image, with the gap at the bottom closed, as in the middle image. This is not a hole, but a concave polygon that shares an edge. This will be supported.

But please don't do it this way. The only sensible way is the right picture: build your models out of convex polygons. In this example 4 quads or 8 triangles.

michiel, 5 months ago


The conversation between you and PiPPi is difficult to understand with advanced content. But it's understandable that the "real hole" you say isn't the opening of a coffee cup.

None of the 3D models I own have holes in them. ((Simply a 3D model without cavities))

I don't have the advanced knowledge of PiPPi, so I'm just guessing, but I think 3D models with "real holes" are rare.


You told me "Michiel is a professional". And you predicted, "Michiel will address this issue soon."

That seems exactly right.

aki, 5 months ago

I don't know if I'm wrong (sorry) but I see that BluffTitler has problems with all figures created in Blender by means of Boolean operations.

Franco Aversa, 5 months ago

here is the object created in Blender with a plane and subtracting a cylinder with a boolean.
This object was imported into Accutrans and saved again.
Then I imported both objects into Blender and you can see how the faces are treated in "edit mode". There is a noticeable difference in how they are divided.

So to solve this problem just after applying the boolean, using a "triangulate" modifier this will make the mesh in Blender equal to Accutrans and Blufftitler will recognize the hole.

Franco Aversa, 5 months ago

and here is the Blender arrow after applying the "triangulate" modifier as you can now see the tail part is correct

Franco Aversa, 5 months ago

as proof of my solution here are two cubes, both with a sphere that cuts them.
But on the first one I added "Triangulate" - green cube
on the second cube where the cut of the sphere is not present I have not added triangulate - red cube

Franco Aversa, 5 months ago

If 3D modelling is not a regular day job, what we're discussing here is so very complicated to comprehend.

As a layperson who knows and likes geometry going back decades, it's a mystery why concave polygons screw up 3D modeling in all sorts of ways, no matter BluffTitler or not.

I do spend time reading things like pro game builders fora etc. to learn all this but no go, I don't work with the nitty gritty details of polygon meshes more than a few times a year so the knowledge does not stick.

Having said that, I can't care too much about the why's and why nots on this subject. If I find a solution by empiric testing, I write it down and use the knowledge although I might not understand all of it.

Like above here. The earlier "hole in the plane" OBJ did not work well in BluffTitler from Cinema 4D OBJ export. I know about mesh triangles and such but how do I actually get it right in my own workflow?

I took heed of Francos findings, thank you very very much Franco, and used a mesh function thats's been in Cinema 4D for years called "Triangulate". Both images are from BT, in wireframe mode and normal.

There are probably much better ways to do it but I select the mesh polygons that give me trouble in importing to BT and do a "Mesh/Commands/Triangulate". That's it, the problem is solved in a few seconds, I don't have to use intermediate software, and I'm now a better 3D modeler due to The Community :)


PiPPi, 5 months ago

That's right, I saw that if the plane was split before when cutting, the mesh that is created already has the different triangulation and the hole is accepted by BluffTitler. But if the plane has no subdivision it is good to "triangulate" after making the cut.

Franco Aversa, 5 months ago

sure @Michiel, however it is not a mistake of BluffTitler. It is a modeling that does not take into account some things, which the user should know for himself. A bit like the speech of the normals, if a normal is inverted the face will be transparent because it is visible from the other side, as if the piece were inside and not outside (this is what I understood .... then not I know if I'm wrong.)

Franco Aversa, 5 months ago

Thank you all for the test files. Version can handle them all!

michiel, 5 months ago

but how do you do it? For my part, you have all the respect ...
If I could I would give Outerspace the "Best Company Ever" award
Motivation: A company that is always listening to its customer, ready to improve at any time, accepting challenges and broadening its horizons more and more ".

BluffTitler: the software that was born as a titler but is able to do everything that others do not do !!

🏆 🥇

Franco Aversa, 5 months ago

Thanks to Franco and PiPPi for giving me a lot of advice in resolving this issue, and of course Michiel.

aki, 5 months ago

Franco, at 3:43 your video shows that Blender seems to use no limit for the number of vertices per polygon. Loading time of models could be reduced dramatically when we could assume that all polygons are convex and have a maximum number of vertices. But it's clear now that we can't... 😟

Version supports OBJ files with concave polygons and an unlimited number of vertices:

michiel, 5 months ago

Comment to this article

You must be logged in before you can comment to this article. Login | Register

More by aki