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[Resolved] Mesh render layers issue


JackTheOtterFox
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Hello and first of all thanks for taking the time to read through my problem.

I have been trying to get into content creation for SL, starting with smaller tasks and working up.
I decided to try to create a nice looking rock/stone, complete with generated textures and bumpmap UV-unwrapped onto the model.

I have however come to the problem that after the import into SL, the mesh seems to stack the render layers incorrectly when viewing from certain angles.
(Like this)

I would try to fix the problem myself, however even after quite some searching on the web I could not figure out what causes this issue, so I'm asking here now.
I would greatly apreciate any help regarding this,

best regards and thanks in advance,
Jack.

 

Edited by Toastfan123
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It's called the alphabug and it's not unique to SL or to mesh but a common problem with virtual reality simulations of all kinds. When two surfaces with transparency overlap, the render engine will always have problems deciding which of them is to be in front of the other and it switches back and forth like what you see in the pciture.

In this case it's easy to fix. There is now reason the rock needs an alpha texture and several reasons (in addition to the overlap problem) you don't want it to have it. Remove the alpha channel from that texture and reimport and problem is fixed.

Alternatively, if you can't do that, change the alpha mode of it to "none"

Edited by ChinRey
Fixing typos
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Also note that there is a bug in Blender that will save your texture as ALPHA on the second (or third etc) baking. So you might have been doing the correct thing (assuming you were in Blender) and just got caught by that. Make SURE whenever you save your texture in Blender that it says RGB and not RGBA. Again this will SHIFT without you doing anything. Hopefully they will fix this eventually a:D.   Just make it a habit to check for now. 

 

 

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Download a copy of irfanview, and run all your textures through it to convert to non alpha channel formats. You mentioned 'render layers' in your rock, what the hell has a rock got multiple layers for.

The only circumstances I can imagine for having multiple mesh layers for a stone surface, is doing ultra high quality slightly translucent marble effects, and frankly for a platform like sl, you're better off compositing a single opaque texture from multiple layers in a 2d image editing app.

People often save images in png format "because lossless quality" and end up accidentally setting it as 32 rgba instead of 24 rgb, I once saw a guy save a rendered preview image of a mesh they had made as 54 rgba and wonder why it wouldn't display on a forum properly. You can use "lossy" formats like jpeg/jpg with the quality setting set to 100, and the "loss" is hardly noticable and you are guaranteed a 24 rgb image,
 

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My recommendation would be to learn how to work with alpha channels in your image editing software, and still use a lossless format like Targa, or PNG. Alpha channels aren't only used for transparency these days.
There is no good reason why you would want unnecessary cormpression artifacts on top of those you get when the texture is imported into Second Life.

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1 hour ago, arton Rotaru said:

My recommendation would be to learn how to work with alpha channels in your image editing software, and still use a lossless format like Targa, or PNG. Alpha channels aren't only used for transparency these days.
There is no good reason why you would want unnecessary cormpression artifacts on top of those you get when the texture is imported into Second Life.

Targas? Hahahaha... Seriously? tga is a pain to use, the whole thing with compressed vs uncompressed tga's, and never mind the cases where applications claim to make one version but actually make the other.

Png is a good solid format, but it's biggest problerm is that it supports not only multiple channle configurations (rgb vs rgba) but multiple bit depths, and many image editing or image using applications don't support the whole range of png options.

As for 'compression artifacts' in images, that does largely depend on the compression level used, 20 odd years have taught me the people who whine loudest about how 'pixelated' jpg's are, are usually those who never learned to change from Adumby Photosnop's default 20% compression.

Oddly, about 10-12 years back, 3D World magazine did an article about people not knowing the differences between and /or limitations of image formats. They did two copies of a 3k x 3k image, one as a high quality/low compression jpg, the other as the then popular choice of tech illiterate format snobs, TIF. They showed both images on a screen to the format snobs and discovered that... the snobs couldn't tell the damn difference without looking at the filename extension.
 

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1 hour ago, Klytyna said:

Targas? Hahahaha... Seriously? tga is a pain to use, the whole thing with compressed vs uncompressed tga's, and never mind the cases where applications claim to make one version but actually make the other.

Png is a good solid format, but it's biggest problerm is that it supports not only multiple channle configurations (rgb vs rgba) but multiple bit depths, and many image editing or image using applications don't support the whole range of png options.

As for 'compression artifacts' in images, that does largely depend on the compression level used, 20 odd years have taught me the people who whine loudest about how 'pixelated' jpg's are, are usually those who never learned to change from Adumby Photosnop's default 20% compression.

Oddly, about 10-12 years back, 3D World magazine did an article about people not knowing the differences between and /or limitations of image formats. They did two copies of a 3k x 3k image, one as a high quality/low compression jpg, the other as the then popular choice of tech illiterate format snobs, TIF. They showed both images on a screen to the format snobs and discovered that... the snobs couldn't tell the damn difference without looking at the filename extension.
 

TGA is the standard for 3d graphics. What exactly makes them so painful to use?

Compression artifacts are definitely something to be aware of, and how severe they are is going to depend as much on the image as the compression level.

TIF is wasted on textures, I agree, but you're definitely going to the notice the difference in print between a compressed JPG and TIF.

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3 minutes ago, IvanBenjammin said:

TGA is the standard for 3d graphics. What exactly makes them so painful to use?


 

 

Trust me when you've spent hours trying to get a tga image to work in some application only to discover that the damn thing only works with UN compressed tga, and the 2d image butchery app provided only saves as compressed tga, you'll feel the pain. I'm also interested to hear who you think sets the standard image format for 3d graphics. PNG's are just as common and often more useful, especially for online work. Point is that people get hung up on a certain 'officially unofficial preferred format' that they don't stop to think what format best suits the intended use. Hence "solid stone wall" textures that come with a 'blank' (show all) alpha layer, which in sl automatically makes them 'alpha blend' when applied to a surface, and creates alpha glitch and additional gpu based client lag as the rendering engine tries to figure pixel by damn pixel if you can see whats behind the solid wall, for no damn reason at all other then somebody got all hung up on using a 'pro file format' that they read about in a forum post, and didn't bother to check the damn save options before exporting from their copy of Adumby Photosnob 2d Image Butcher.
 

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49 minutes ago, Klytyna said:

 

Trust me when you've spent hours trying to get a tga image to work in some application only to discover that the damn thing only works with UN compressed tga, and the 2d image butchery app provided only saves as compressed tga, you'll feel the pain. I'm also interested to hear who you think sets the standard image format for 3d graphics. PNG's are just as common and often more useful, especially for online work. Point is that people get hung up on a certain 'officially unofficial preferred format' that they don't stop to think what format best suits the intended use. Hence "solid stone wall" textures that come with a 'blank' (show all) alpha layer, which in sl automatically makes them 'alpha blend' when applied to a surface, and creates alpha glitch and additional gpu based client lag as the rendering engine tries to figure pixel by damn pixel if you can see whats behind the solid wall, for no damn reason at all other then somebody got all hung up on using a 'pro file format' that they read about in a forum post, and didn't bother to check the damn save options before exporting from their copy of Adumby Photosnob 2d Image Butcher.
 

When I was new in SL I used tga, but my current graphics program cannot SEE tga (as an image) in the Windows explorer -- so THAT doesn't work well at all. 

Also using a texture with an alpha channel increases the texture download in world needlessly and takes longer to rez. You can of course take an alpha texture that you uploaded by mistake and change that in the build menu to "none" but that texture is still having to be rendered -- is that not correct?  

Best to just pay attention when you save from Blender. The bug of course is only in Blender, not other software. Still, you can easily forget that you have your export to include an alpha channel in your graphics software and end up with a larger file. 

 

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5 hours ago, Klytyna said:

Targas? Hahahaha... Seriously? tga is a pain to use, the whole thing with compressed vs uncompressed tga's, and never mind the cases where applications claim to make one version but actually make the other.

Png is a good solid format, but it's biggest problerm is that it supports not only multiple channle configurations (rgb vs rgba) but multiple bit depths, and many image editing or image using applications don't support the whole range of png options.

As for 'compression artifacts' in images, that does largely depend on the compression level used, 20 odd years have taught me the people who whine loudest about how 'pixelated' jpg's are, are usually those who never learned to change from Adumby Photosnop's default 20% compression.

Oddly, about 10-12 years back, 3D World magazine did an article about people not knowing the differences between and /or limitations of image formats. They did two copies of a 3k x 3k image, one as a high quality/low compression jpg, the other as the then popular choice of tech illiterate format snobs, TIF. They showed both images on a screen to the format snobs and discovered that... the snobs couldn't tell the damn difference without looking at the filename extension.
 

Hahahaha... yeah seriously, Targas! But hey, be happy with your compression artifacts, especially on your tangent space normal maps. :SwingingFriends:

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3 hours ago, IvanBenjammin said:

TGA is the standard for 3d graphics. What exactly makes them so painful to use?

Compression artifacts are definitely something to be aware of, and how severe they are is going to depend as much on the image as the compression level.

TIF is wasted on textures, I agree, but you're definitely going to the notice the difference in print between a compressed JPG and TIF.

I do use 16 bit Tiffs to export baked normal maps from XNormal. They will be converted to 8bit targas in Photoshop later on, to avoid banding artifacts.

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3 hours ago, Klytyna said:

 

Trust me when you've spent hours trying to get a tga image to work in some application only to discover that the damn thing only works with UN compressed tga, and the 2d image butchery app provided only saves as compressed tga, you'll feel the pain.
 

Well that happens only once, and you know how to convert it to the format needed.

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2 hours ago, Chic Aeon said:

When I was new in SL I used tga, but my current graphics program cannot SEE tga (as an image) in the Windows explorer -- so THAT doesn't work well at all. 

Also using a texture with an alpha channel increases the texture download in world needlessly and takes longer to rez. You can of course take an alpha texture that you uploaded by mistake and change that in the build menu to "none" but that texture is still having to be rendered -- is that not correct?  

Best to just pay attention when you save from Blender. The bug of course is only in Blender, not other software. Still, you can easily forget that you have your export to include an alpha channel in your graphics software and end up with a larger file. 

 

When I mentioned "learn how to work with alpha channels in your image editor" that includes adding and removing alpha channels as well indeed. It's always best to have one application that you know it works as intended to export out your final stuff, be it textures, or models.

Of course a texture with an alpha channel will always be downloaded with that alpha channel, because Linden Lab doesn't store 2 different versions of these textures.

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3 hours ago, Klytyna said:

 

Trust me when you've spent hours trying to get a tga image to work in some application only to discover that the damn thing only works with UN compressed tga, and the 2d image butchery app provided only saves as compressed tga, you'll feel the pain. I'm also interested to hear who you think sets the standard image format for 3d graphics. PNG's are just as common and often more useful, especially for online work. Point is that people get hung up on a certain 'officially unofficial preferred format' that they don't stop to think what format best suits the intended use. Hence "solid stone wall" textures that come with a 'blank' (show all) alpha layer, which in sl automatically makes them 'alpha blend' when applied to a surface, and creates alpha glitch and additional gpu based client lag as the rendering engine tries to figure pixel by damn pixel if you can see whats behind the solid wall, for no damn reason at all other then somebody got all hung up on using a 'pro file format' that they read about in a forum post, and didn't bother to check the damn save options before exporting from their copy of Adumby Photosnob 2d Image Butcher.
 

Wow, you really don't like photoshop, huh? :D 

All the problems you describe are user error and/or application limitations, not the fault of the image format. TGA is standard across the game industry because its uncompressed and lossless. It can then be compressed as needed when game files get 'cooked'. PNG is fine if it does what you want - I'm not here to tell you how to work - but they're awkward to work with if you need an alpha channel for something other than transparency. I'm currently working with Unity, and its shader system has inputs for Diffuse/Albedo, 'Metalness' and Gloss (plus other things). If I'm doing a surface that needs to be glossy but isn't metallic, I can use the Diffuse alpha channel for gloss and avoid using another separate map.

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3 hours ago, IvanBenjammin said:

Wow, you really don't like photoshop, huh? :D

All the problems you describe are user error and/or application limitations, not the fault of the image format. TGA is standard across the game industry because its uncompressed and lossless. It can then be compressed as needed when game files get 'cooked'.

Experience in games modding and 3d work over the last couple or 3 decades tells me there are very few "standards" in the games industry.

I've worked with tga's in old games like neverwinter nights (which isnt fussy about compressed vs uncompressed until you start on character portraits, when it throws a wobbler. The IDTech 3 game engine, was also a tga based system, but happily swallows png's as well, its internal shader system even makes virtual tga's at load/run time. However claiming that tga is a 'standard' seems to miss out all those games that settled on .dds format (why anyone would use dds i cannot imagine, especially dds dxt1 which has a lossy compression standard WORSE than the default jpeg settings in Photosnob) or jpg's or custom formats of their own devising. Even second life it's sell, breaks the 'standard' since as far as I remember, it's internal file format is jpeg2000.
 

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4 hours ago, arton Rotaru said:

I do use 16 bit Tiffs to export baked normal maps from XNormal. They will be converted to 8bit targas in Photoshop later on, to avoid banding artifacts.

I hope you are happy with the quality drop or 'artifacting' that you will get by converting from 16 bit greyscale to 8bit with photosnob.

True story, I once severely annoyed a clueless postwork buffoon, buy demonstrating how they could get the same low quality images they normally produced in 12.5 % of the render/postwork time...

Their method:

Render at TWICE desired output size, perform clumsy digital fingerpainting to hide the errors in their render caused by lack of 3d technique, then reduce image quality by adding the almost compulsory forum-fool-advised 'guassian blur', THEN reduce image size 50% using a less than brilliant tool in photosnob.

The alternative I suggested:

Render at half desired size, clumsily finger paint, then resize with the same tool to desired output size, the blurring from the low render size and crude upsizing will match the quality loss of the gussian blur, and rendering at HALF size instead of DOUBLE size means a 92.5% drop in raytracing time and postworking time (92.5% fewer pixels to fingerpaint over) .

For the record, personally I used neither method myself, preferring to render at desired output size, and a) fix render errors in the rendering app, in 3d not afterwards with clumsy postwork, and b) despising the use of 'gussian blur uber alles' because it does not add 'gritty realism', it just adds blur..
 

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1 hour ago, Klytyna said:

I hope you are happy with the quality drop or 'artifacting' that you will get by converting from 16 bit greyscale to 8bit with photosnob.

I don't know if it makes me happy, but I'm certainly satisfied with the result. The dithering PS applies when converting 16 bit/channel to 8 bit/channel is the whole point of why it's done. xD Though, my normal maps are certainly not greyscale to begin with. ^_^

Edited by arton Rotaru
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28 minutes ago, arton Rotaru said:

I don't know if it makes me happy, but I'm certainly satisfied with the result. The dithering PS applies when converting 16 bit/channel to 8 bit/channel is the whole point of why it's done. xD Though, my normal maps are certainly not greyscale to begin with. ^_^

I've always found the dithering in PS to be on par with the artifacting in a minimal compression jpg, so... You're happy, I'm happy, you get your 8 bit normals, and I get to comply with max file size limits on online gallery sites, without having to compromise on image resolution while still retaining 'acceptable' image quality.

The expression is "horses for courses", which is why there is NO "single perfect image format we should all use all the time".
 

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15 hours ago, Klytyna said:

Experience in games modding and 3d work over the last couple or 3 decades tells me there are very few "standards" in the games industry.

I've worked with tga's in old games like neverwinter nights (which isnt fussy about compressed vs uncompressed until you start on character portraits, when it throws a wobbler. The IDTech 3 game engine, was also a tga based system, but happily swallows png's as well, its internal shader system even makes virtual tga's at load/run time. However claiming that tga is a 'standard' seems to miss out all those games that settled on .dds format (why anyone would use dds i cannot imagine, especially dds dxt1 which has a lossy compression standard WORSE than the default jpeg settings in Photosnob) or jpg's or custom formats of their own devising. Even second life it's sell, breaks the 'standard' since as far as I remember, it's internal file format is jpeg2000.
 

TGA is "standard" in the same way that photoshop is "standard". It's not universal, just best practice. Also, we're not talking about internal formats here, we're talking about the format that you, the artist saves your work as. The point of TGA is that its lossless - you want to avoid at all costs feeding a lossy compressed image into a different compression algorithm.

I repeat, I'm not here to tell you how to work. If you want to use PNGs, fine. If you want to use jpgs, fine. This whole "debate" started because you expressed a negative opinion for a widely used image format - an opinion that apparently stems from the limitations of your tools. Personally, I've never had issue with unwanted compression in my TGAs (I didn't even know that was a thing...), but maybe that's because I use photoshop... 9_9

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I wouldn't call Photoshop  a 'best practice'.  It's got a dominant market position all right, and lots of people don't know anything else - why would you even try anything else when you have shelled out all that loot for an Adobe product?   Adobe is one of those anti-trust oligopoly companies, like Apple and Microsoft, that some of us wouldn't pay a bent nickel to.

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2 hours ago, Pamela Galli said:

I bought PS. But I use Gimp.

I've got GIMP, but I use Photoshop.  And I will make either PNGs or TGAs, depending on my mood and the task.  I am far from a pro -- I'm a scripter with moderate artistic skills -- so I use the tools I've learned from smarter people. I find it a lot easier to use TGAs when I am doing anything tricky with the alpha channel, but that's mostly because I learned the basics when Chosen Few -- a rabid TGA fan -- was still among us. 

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