Asset: Crappy Cowboy Video Textures

David Swoboda

To really get your head around this idea of straight or premultiplied alpha, I'll recommend the book "The Art and Science of Digital Compositing" by Ron Brinkmann. It's a must-read for all compositor's

Doug Brown

Just an overall process breakdown (modelling and texturing)... feel free to spend AAAGES on it ;) ;)

Ian Hubert

Oh! It's the cowboys themselves that are crappy- I think the scene turned out nice :D But yeah! Is there any particular aspect you're curious about, or just an overall kinda breakdown?

Doug Brown

Hey Ian... any chance you could breakdown the crappy cowboy scene please? Looks awesome... not crappy at all... THanks.

Ian Hubert

Oh, thanks Michael! So in this case most of the weight is being carried by a roughness map. The color itself is just a flat beige, but I have a (fairly random, actually) image texture going into the roughness setting in the PBC node (dialed in slightly with a color ramp), and that made it feel surprisingly tactile! I talk about it a bit in this video here at 12:17: https://youtu.be/hnGBlt1FXCw?t=737 Sorry I didn't see this till now!

Sweet renders boss, how do you come about your textures they are amazing..... You have a pbr workflow? Cos the level of dirt detail in the printer and showing age and wear is so mesmerizing

Ian Hubert

Ah! I'm glad it got figured out! Thanks for seeing this, Stefan! :D

Great help, it worked! thanks a lot!!

it's that guy!

If you go to the "My Membership" page, you'll see an option that lets you connect Patreon to your Discord account!

David Byrne

It is absolutely useful, I tried to find the Larry Grist mailing list but it kept directing me to a 404, but I feel like I've learned a lot with just your posts, and it's made me re-evaluate my decade long rule - I will continue with the vast majority of work to just use Straight Alpha with AE PNG sequences for quick corporate jobs and the like, but excellent to know this for more refined work and vfx that needs more attention. I will follow the 3 rules you've added! And try to get into it, to find where and when to spend the time and effort making sure this way of working is used. Thanks again Nathan! (And if you do happen to stumble on a copy of the Larry Grist link please do add it!

Hello Ian, I joined a couple weeks ago but I still don't know how to access discord. Can you help me? Tnx in advance.

Wow, those two frames look amazing! Were those done with Cycles or Eevee? Thanks for the stuffffffff!!!!

Nathan Vegdahl

Yeah, just trying things until it works is a pretty good strategy to be honest, ha ha. But there is a correct and incorrect way to do things with straight vs premultiplied image assets, so it's easy to accidentally go wrong. It's important to keep in mind that, assuming you're using the right assets with the right kind of alpha compositing, you should never get artifacts with either type of alpha compositing. They can both do perfect clean composites. So any time you get either a dark fringe or bright halo effect it means one of three things: 1. You're using the wrong kind of alpha compositing for the given image asset. 2. The asset itself is busted in some way, and isn't actually valid for either kind of alpha compositing. Or, for example, if it's keyed from a green screen maybe the key just sucks--basically the same thing as busted alpha, ha ha. 3. The software you're using is busted, and one of the types of alpha compositing doesn't work right. Usually it's 1 or 2. Be especially mindful of compositing with PNG images: they should always be both saved and composited with straight alpha, because a lot of software tries *really* hard to treat them as straight alpha due to the specification. One trick to keep in mind: if your compositor has anything like a "convert to premultiplied node" (in the Blender compositor it's "alpha convert"), using that followed by a premultiplied alpha composite is literally identical to doing a straight alpha composite directly. The math is literally exactly the same, and should produce identical composites. If it's not identical, something is fishy with your software, or there's something wrong in your node configuration. But also, this is useful to know if you want to keep a premultiplied workflow but are working with PNG assets: just put a convert-to-premultiplied node right after all the PNG image nodes, and (assuming the software isn't buggy, or doesn't auto-convert already in the image node) you should be golden. Sorry for the wall of text. Hopefully that's helpful!

Ian Hubert

Ah! I hope they can be useful? Also oh nooooooo, haha, it's true. I think I use it to signal, "hello, I am attempting to communicate using, like, a casual vernacular". Text is hard!

Strobez

Oh man, that subway shot looks amazing!

Carkoon

Thanks! That's super fair and cool.

Lukas Sprehn

I have literally been waiting a year or more to see what the still frames of this scene were all about! It looks so interesting!!

Benjamin Lacey

Dude, thanks! Thank you for explaining about the teaser trailer, thats really helpful! This little clip does look even more polished than the teaser, good stuff!

Phillip Park

Haha thats great!

David Byrne

Thanks Nathan- this is really interesting, I'm only used to using AE for compositing, and premultiplied in there just looks pretty terrible on anything I've ever tried - but I guessed there had to be a reason for it being in there! And interestingly I use PNG sequences all the time, so that may be part of the issue. But yeah I think I've never gone wrong with it in AE, but interesting to know that this is a software and formats issue. Cheers! Also really interested to hear about the Blender composting stuff Ian, I'm just getting started again with Blender and haven't used it for composting at all but guess Nathan's point about the software just shows that it may be you use a particular alpha dependant on whether using AE Blender or other software. Fascinating stuff!

Kennisoan

Haha, that’s amazing! Also, have you noticed that each Ian’s reply starts with “Ah!”

Ian Hubert

Ah! Thanks for that, Nathan! I feel better about being confused. I read this big ol' explanation a couple years ago that went super in depth about all of this, and for a few glorious moments the heavens parted and I was like, "I get it!"... but then the rains came. I think I'll probably just try all combos of stuff for each workflow and try to figure out what works best in each case.

Nathan Vegdahl

So, strictly speaking, premultiplied alpha is the correct way to do things. Well, maybe "correct" is too strong of a word. But better, at least. There's a beautiful rant from Larry Gritz about this on some mailing list somewhere, and about how "premultiplied" is a horrible name because it makes people think something has been done to it, rather than it just being an alternative representation. But basically: premultiplied is strictly more capable than straight alpha. It can do everything straight alpha can do, and more. For example, you can have fully transparent but emissive pixels that add light to the background (think e.g. fire effects, or bright reflections on transparent glass). Straight alpha can't do that: your pixel can be bright and opaque, or dull and transparent, but it can't be bright and transparent. With premultiplied it can be. This has actually come up in real gigs for me before. I had a client that for the life of them couldn't figure out why the composites of their glasses were coming out so dull and lifeless. It's because they were using straight alpha, so all the bright highlights on the transparent lenses were going dull. We switched to premultiplied, and regenerated the assets in the right way, and then it all worked beautifully. Having said all of that, in practice so much software gets this stuff wrong that it often *is* better to just use straight alpha, unless you have a specific use-case that needs it. In fact, finding software that can even *create* image assets that properly utilize the benfits of premultiplied alpha is really hard. And in fact, there are file formats (like PNG) that actually *require* straight alpha in their specification, because whoever wrote the spec didn't know any better (which is completely understandable, btw, this isn't even common knowledge now, much less back when the PNG spec was written). In summary, in a sane world everything would be premultiplied alpha, but that's not the world be live in. So you gotta be pragmatic. But also, complain to your software vendors about their broken premultiplied alpha, because it would be nice to get there one day.

Ian Hubert

Ah! Yeah I guess I don't talk about that much. I'll specify if they have any restrictions. The only real restriction is, "don't take the models/textures and re-sell em", but using them as assets in renders/commercials/anything is totally open. You can give them to other folks, too; mostly these are just things I made that I want to make available to folks in case they find them useful.

Ian Hubert

AH! Hahaha, these guys make even better steampunks than they do cowboys, probably! That's great :D I'd love to see how it works out! I guess a third thing I learned: I did a lot of "extra wiggling" because I wanted to sell that it wasn't just a bunch of still images... it definitely just comes across as "extra wiggling" though- I'll have this figured out for next time! Although I still gotta come up with that mocaped-crowd solution (hopefully very soon here!) HAH! I could even add a "cyberpunk" slider which just turns on an emission texture for various edge loops, Tron style, haha. And glowing eyeballs.

Ian Hubert

AH! Thanks for this! Yeah, in the blender compositor the keying never looks good until you use a "convert alpha to premultiply" node (and then it usually looks pretty fantastic), so I got in my head that premultiplied was this fantastic thing- but apparently it's been burning me quite a bit this past year, so I'm going to avoid it when I can! Definitely useful for making future pre-keyed assets!

Carkoon

Interesting stuff! A more general question: What's the license on the assets that you upload here? I myself am not a professional and would if at all probably use them only in personal stuff but maybe it would be good to clarify?

keith hamilton

Yeh might fine of you to present us with those here assets...Sir

Ry Ken

Awesome I’m so glad you make content like this for blender.

Carter Burr-Kirven

Ooh, thanks for these! Great timing—I’ve been working on a steampunk scene and going through that same process trying to convince myself I can get by without BG crowd elements even though I really need them, so it was either set the greenscreen back up and populate the scene with 50 Carters in different hats or try to find some appropriately dressed 3D models, but “cowboy” might be juuust close enough to “Victorian” to make this scene work without all that hassle!

David Byrne

Great thanks Ian, more amazing stuff! Your assets have now their own folder in my GFX repository, they're superb thanks man. For anyone wondering about Straight Alpha vs Premultiplied, just use Straight. I haven't yet seen a case that used Premultiplied that was beneficial. The only disadvantage isn't even a disadvantage, its a quirk- Straight Alpha looks more crunchy if viewed directly in QT as the edges don't blend until they are composited, but honestly just use Straight. Pretty sure I got this from AE legends Chris and Trish Meyer back in the day, and has helped me through the years! I would genuinely be interested if anyone has any cases where they chose Premultiplied for a specific reason, as I've yet to run into one, but there must be a reason for the choice (and the fact that it's the default option, if memory serves).