Why do flat-surface 3D objects have shading artifacts???

[VeryAnnoyed2016]

Hello all - Just trying to put a 3D object in some art and have it shade properly.  Running into several issues.  Have years of experience with PS Elements, and am brand-spanking newbie to the full PS [Side Bar: is there a way to just buy the blessed full-featured 2019 or whatever latest PS (am not even sure of the name as there seems to be multiple versions CC this CC Pro that--I think the one I am using does not even have the CC) rather than the subscription approach?].  

1. The object is modeled with flat faces.  The .stl files have flat faces.  But when I add textures and save as an .obj, I get these weird shading artifacts that guessing there is a name for and it is a well-known thing.  Including a portion of the image below.  The shading artifacts are lots of v-shaped straight lines along the background surface that appears to be some sort of mathematical artifact from the mesh process.  (Seeking some education in this area.)  I tried making the .obj in Meshmixer and 3D Builder, same thing.  I tried importing the .stl into PS and then generating UV's, same thing.  The object is nice and flat until last step to make it useable...then garbage.  So, question #1 is understanding what is going on and how to get rid of this "puckering" shading artifact.  [Ego Disclaimer #: DontJudgeMe404. This is not how the final 3D object is intended to be textured, yada yada--this is earlier version I am backtrack experimenting with to resolve issues.]  

Thanks in advance for the info,

Richard

[Ussnorway]

the screenshot you posted looks like a shadow effect ... I'd use Dimension in stead of Photoshop because putting 3D objects in front of 2D backgrounds is what Dimension is designed to do

that said, if you share the files I'll take a better look

[VeryAnnoyed2016]

Sounds good will check into it.  Hoping Dimension is free/cheap.  Would like to create bump map for the 2D scene to up-level the shading effects.  Hoping to find something easy to use to do that.

[Mylenium]

These are smoothing artifacts. You need to play around with the smoothing tresholds in the materials. In an ideal scenario you would avoid them entirely by taking your object to a 3D program and letting it generate proper normals, then save it in a format that is actualyl able to retain that info like FBX, DAE, 3DS, OBJ. STL is unsuitable for such a workflow because it exactly doesn't do that. It's merely meant to carry the geometry for 3D printing, where smoothing for shading would be irrelevant.

Mylenium

[VeryAnnoyed2016]

Well as indicated in post, I did create .obj's in 123D and 3D Builder both, but get the same issue as when I import the .stl into PS and generate UV's (which evidently is an equivalent process).  I tried to use Blender before but was baffled by its UI.  No idea why Autodesk 123D would not be generating proper normals.  It looks fine in 123D...but no textures added.  The problem only comes about when textures are added...in other programs...because 123D does not do textures.  Surprised that 3d Builder (Microsoft) would screw up the normals...???

[VeryAnnoyed2016]

It does seem like the smoothing issue is only an issue with the textures.  No problems until textures added, either in 3d Builder or MeshMixer.  

[davescm]

It could be several things such as:

Bad Geometry - it looks like those letters are set into the geometry and the smoothing algorithms are having to cope with them.

Need to remove backfaces

Scaled UVs (there is a bug affecting those)

Without seeing the model it is hard to advise, but you may need to take the model into Blender (or similar) and sort the issues there before brining it back into Photoshop for rendering (or just render it in the 3D app).

Can you post a link to the PSD file?

Dave

[VeryAnnoyed2016]

Thanks Dave.

The geometry was made in Autodesk 123D, but having said that...when I
import it into 3D Builder, 3D Builder does do some repairs on it. But even
after repairs, still does this. Note that after repairs, MeshMixer
indicates zero issues of any sort with it. So can I rule out Bad
Geometry?

No idea what backfaces are or what to do to remove them. Can say that the
affected item is not a composite merge of objects, if that is what this
means. It is an object that had spline volumes subtracted from a block to
get the new object. Note the issue is not merely around the engraved
letters, either. It appears on object even before letters were applied.

Do not know what UVs even are, but infer they are part of .obj that
includes texture info. Can say that 3D Builder .obj has the issue.
PhotoShop import of .stl does *not* have them, until I generate UV's from
within PS...then it has them.

Richard



--
The most terrible poverty is loneliness, and the feeling of being unloved.
― Mother Teresa

Karma is not always direct. Sometimes it comes through our feelings for
those we love, who whether blessed or cursed must live in the world we
helped create.
― Unknown

[rayek.elfin]

If you share the STL object with us, we can probably explain to you how to fix it. As mentioned by others here, it is a face normals issue, and needs to be fixed in a 3d app such as Blender.

[VeryAnnoyed2016]

Sounds good.  I did look at Blender but was totally baffled by the UI.  Can you give any words of encouragement for ordinary humans trying to use it?  🙂

[Ussnorway]

thats great mate but you missed the key point... we need to see the actual file before we can help you more

[VeryAnnoyed2016]

Ok!  Have the links in a reply to OP.  

[VeryAnnoyed2016]

Ok!  Well the coffee is online and I figured out how/where to put the files and provide requested links.  Here is the 

Here is the .stl file:  https://drive.google.com/file/d/1Vb7kC8ajeiQV5laIt4q7gLBGBQDTv9Kn/view?usp=sharing.  

And here is the Autodesk 123D file: https://drive.google.com/file/d/13Qn1XvW3UwZTFCohvxXSRyBlJiwuR-Q2/view?usp=sharing.  

[VeryAnnoyed2016]

They should both look fine, though 3D Builder did indicate it was "repairing file" when it imported the .stl.  Still, once repaired, there will be no issue with the faces.  The issues only pop up once textures are added.  

[rayek.elfin]

Two things stand out:

- the normals should be auto-smoothed

- the object is not uv-mapped, and should be uv-mapped in 3d software.

I attached a blend file which can be opened in Blender, and mapped the UVs quickly. Not great, but it should work better now. Also turned on auto-smooth and smooth surface properties. The texture should ideally be at least twice as long, or seamless and then stretched across the surface for best effect.

Open the file in Blender, then export to Collada (File-->Export-->Collada dae). Open this Collada file in Photoshop. (Blender is open source and free: https://www.blender.org/)

PS if you want a nice looking quick render, avoid Photoshop's aging and tired 3d renderer. It is decrepit compared to modern solutions, and is incredibly slow to render with, while the render quality looks like something from two decades ago. I would just render in Blender: fast and great quality, then import into Photoshop. Ideally also some bevelling should be added to the (too) sharp edges.

I used this wood texture: https://cc0textures.com/view?id=Wood026

https://drive.google.com/file/d/1auJha3tAqq4Pe3ZTF4sHK5x4JekSxT7u/view?usp=sharing

PS hit F12 in Blender to render in Eevee.

[VeryAnnoyed2016]

Awesome info, will try it.  Thanks.

[VeryAnnoyed2016]

Hmmm well...?  So I opened the file in Blender and exported it to Collada dae [which is what, the species of creature that designed Blender UI?]  Note while in Blender I tried to texture and could not figure out how to do that, even with video tutorials.  I did note that if I click on "Modeling" I see the same old stymie:  

"Model" option in Blender

So then I went into PS and saw two things: 1) no texture is visible; 2) I cannot add a texture in PS.  

Taken from inside PS

So to summarize: since I am [redacted--Adobe does not let me say our genus hahahahahaha] sapiens rather than Collada dae, it probably is my fault that it is not working.  What really baffles me is why I must jump through all these hoops just to texture an object to upload into PS.  I have uploaded 123D files into Flowscape using the exact same process before.  Flowscape takes the .obj which was textured in 3D Builder and renders it just fine with the scene lighting.  The only problem is that the object placement controls in Flowscape are heinously oppressive, inaccurate, and tedious to use.  It could literally take me a day to place the object where I want (unless you are the species Imagen dragonia, which developed Flowscape).  So crazy me, I thought it would be simple to import an .obj using the same process into PS, fiddle with some lighting controls, and use the Flowscape scene as a 2D background.  #IStandCorrected  #AllHailOurNewOverlords #ColladaDae   

[Ussnorway]

this is a down and durty example of your [unedited] Stl file in Adobe Dimension

test rendor

I didn't want to do much to it so I just cut the background out of your image and picked two materials... If I had more time I would fix up the letters but this only took a few clicks and about 5 mins for my work laptop

Just to be clear, I use Blender and Photoshop all day every day and they both do some things better than Dimension... at the end of the day use what works for you mate

[VeryAnnoyed2016]

Ok!  Well that looks like what I am aiming for--blessed flat faces.  No idea why have to do all the gymnastics to get from Autodesk 123D to Photoshop...but let's dance.  Thanks for showing me how to do the Dimension stuff, will check it out.  

[Ussnorway]

Autodesk is a software giant that made lots of money on Cad and Maya back in the ye O days before Blender came along... they make Adobe look like a mum and dad store but software that doesn't talk to each other is very much the norm

p.s, when you want to do small details like fixing the letters with the magic wand it can sometimes be hard to get [just] the part you want selected... a good work around is to temp adjust the scale up from 1-10 which makes the model itself bigger and selecting correct area easy

[VeryAnnoyed2016]

Up next, I attempt to unravel the mysteries of Dimension.  Wish me luck, am going in in one coffee.

[VeryAnnoyed2016]

Oh My Sh*t!  It actually took the .stl.  (The .obj gave it *slight* problems.)  Then, I merely clicked on a material and it, and it, and it...*sob*...textured it!  Now, the only remaining--hopefully small--issue is how to ungroup the objects.  I had to group them during export in 123D so would get all objects.  But I want each object to have own texture.  Am working on that.  Alternately, I can export individually and hopefully snap together in Dimension if need be.  Bonus points if is easy to import/create/buy other texture files--but am happy with reasonable selection of default materials.  

Sure...one test remains...exporting the result and importing into PS or else importing the 2D image as a background in Dimension and operating the lighting.  Sorta leaning toward trying the latter first.

[Ussnorway]

giving different materials = magic wand tool [as my screenshots show]... just select a face and click a new material

exporting into Photoshop = rendor as Psd

p.s, Obj is an old standard and what Autodesk exports is not quite correct but Photoshop can normally open odd Obj files and re-export them as a true wavefront Obj... have fun

[VeryAnnoyed2016]

Update:  Well I tried selecting a surface and choosing material and it worked...for a while???  Then somehow it got into mode where it only applied material to whole object.  I tried using the "subtract selection" no luck.  I tried ungrouping but it is greyed out not available (likely due to how I exported from 123D as grouped).  I tried changing the selection *size* from tiny to small, no luck.  So, I know it can do it, but am not understanding whatever I did to put it in a different mode.  

Also, presume there is way to set the parameters for the given material (opacity, luminence, roughness, etc.)...?  Can play around with that.  I tried the "glow" material but it just made the selection white.  

Lastly, and amazingly, I rendered to .psd...but PS does not show the file when I try to open it??  In other words, I cannot open the file from inside PS but I can open the file *into* PS from clicking on it in File Explorer.  *sigh*.  

But the biggest thing, is I was hoping to export the file as some sort of 3D object that I could then import into PS as a 3D Layer...and things would just work right.  But amazingly not seeing a way to import a 3D object made by an Adobe program into an Adobe program that works with 3D layers.  #CrackCocaine  #SweetBabyMultiEthnicJesus.  #Coffee

[VeryAnnoyed2016]

In fairness, am prolly asking too much of either Blender or Dimension--to easily handle my specific situation when there are millions of situations they are designed to handle.  It just *seems like* what I am trying to do would be one of the foundational use cases...create 3D objects and plug them into 2D images.  So my *expectation* is prolly skewed, expecting that to be simple & intuitive and hassle-free, based on standardized protocols that everyone adheres to.    

AT ANY RATE, am within striking range of making this work...which is really all that matters.  I can workaround the mentioned stuff--really just mentioning it in case there is obvious/easy tweak I am not seeing.  So, can otherwise consider this: Problem Solved.

Many thanks to the Adobe community for your patient help.  May I be able to repay this, with contributions of my own toward questions of some sort.  

Thanks!!!