Skewmesh Tutorial
greentooth
A little Tutorial I did on how to get a bake without skewed elements for hard surface models, hope its helpful:
Max: https://www.youtube.com/watch?v=u8nvDgvKbSs
Xnormal: https://www.youtube.com/watch?v=NRNL_21Ee_w
Max: https://www.youtube.com/watch?v=u8nvDgvKbSs
Xnormal: https://www.youtube.com/watch?v=NRNL_21Ee_w
Replies
Going to be abusing this for sure
thanks man!
that's what i thought immediately. and i think handplane is free?
Might have to think about this and try some tests tomorrow, as it could speed things up, and I don't see a downside if you're going to be using OS to ts via handplane anyway. Maybe cages have some other advantages I'm not considering.
edit: like cages giving more control per piece than having a global ray distance. Which might be quite important when you have parts at fairly different scales.
As rays are cast through vertices, simply doing a bake with a higher poly lowpoly would solve that issue. Copy the lowpoly > tesselate (subdivide) without smooting, and bake that + cage. Take the gained map, use it on the real lowpoly and done (unless I mix something up here ?)
The first video uses endless crazy steps and a object space map when you only need more vertices for a more accurate bake, but please correct me if im wrong
What I'm thinking is if you do this, you could get near enough to cage-like results using ray distance / averaged normals (doing in theory the same thing as a lowpoly + averaged cage, minus cage's ability to fine tune ray distance) on your subdivided lowpoly when baking an OS map (which you were probably going to do regardless). I did some quick tests and it seems to work quite well, but cages still seem to be the best option; so cages + subdivided lowpoly bake give the best possible results, but subdivided lowpoly + ray distance bake are pretty good too, and potentially a lot simpler/faster.
did you even try what you just said? you can't just bake a tangentspace map from one mesh and put it onto another. Sometimes it might work, if you are lucky. But good luck once you use synced normals.
basically what you wrote is exactly was Peter did, besides he baked an object space map he can convert to a synced tangentspace map.
I remember working around the issue by doing what I described but maybe I did combine the 2 maps afterwards or something like that, didnt have any mesh at hand to test it out right now, my bad.
More and more info, the puzzle completes itself, Nice!
I never had luck with handplane, really dunno why
From some testing I did the other day my conclusion is that using a 'skew mesh' is a pretty specific thing to do. By that I mean you will use it if you're getting significant skewing problems on an important mesh, or possibly (still need to do more testing here) if you notice significantly better results when doing a ray distance bake. That seemed to be the case for me, but I'm not sure why, so I'm not sure if I was doing something wrong or if using a skew mesh gives significantly better results with ray distance.
For the best possible result you'll use a cage + 'skew mesh' but that's also the longest process, so if you can get good enough results using RD/skewmesh it might be a decent timesaver. And that's particularly interesting for us modo people because we can quickly bake an OS map in modo (no need to export; and this also means we can use the rounded edge shader) and convert to TS with handplane.
Yeah, that method is useful where most of the mesh consists of the parts that prone to skewing(as in that example, a radial cog with lot's of screws etc on the surface), other than that normally it's somewhat predictable where skewing might occur so the places to add support loops. I feel like in some specific cases it can be a good blanket solution to cover whole mesh otherwise adding edgeloops onto the low poly might be too tiresome.
By saying ray distance method, do you say baking one skewed cagebake and one non-skewed ray distance mesh and patch the skewed parts in ps?
Yes, that's correct. Only the tangent space map needs the extra work. You'll be able to use other maps on the low poly mesh without any further messing around (except derivative maps if you're using those, they're still linked to the tangent basis).
thanks farfarer !
btw love your unity plugin for xnormal it is awesome!:poly142:
I still work this way too, since being able to do every bake in one shot, with no conversions, is a lot more appealing to me than having to work through: tessellation -> object -> lowpoly -> tangent
As for wasting time thinking about where to add the geo, test bakes help a lot. While making the lowpoly, periodically do an auto-UV, bake normals, check it out in-engine. Add geo to fix the vertex normals where you see skewing, ray misses, etc.
Test bakes take almost no time and make it easy to catch all kinds of artifacts way before you're even done modeling
The main issue i see here, is that if you need to edit manually that cage, it would be kind of a pain.
You could create the cage on the original low poly, then export the cage, subidivide it, and import it on the subdivided mesh. See what i mean ?
Or do you think there's no need to edit a cage manually with this method ?
Well if the asset you're using doesn't need the benefits of a cage (specific distance values for certain areas) you might as well bake in OS with Ray Distance / Averaged normals as that's doing pretty much the same thing.
If you're already using a script to automate your export of high/low/cage all you'd need to do is insert a step to export a subdivided low.
It's the temporary subdivided mesh used to calculate a temporary normal map with low distortions.
Amsterdam Hilton Hotel : Skewing, yeah, waves on cylinder adjusted for a certain pov, interpenetrating stuff...Seems more simple to set the cage on the low poly rather than on the subdivided one.
Anyway, no big deal, i can script that.
http://wiki.polycount.com/wiki/Normal_map
If you're baking to tangent space, you can't remove geometry without introducing smoothing errors, as you're changing the mesh normals as tangent space maps are tangential to the mesh normals, hence the name.
If you can link me to the specific post you're talking about I'll take a look and perhaps edit it to reduce any further confusion.
Aha, good catch! Yeah, I have the numbers wrong in the text there Fixed it now, thanks.
Or smooth the mesh after creasing all edges
Does the object space map look correct?
If the OS map is distorted, maybe you're not using enough divisions, or your lowpoly shape is too different from the hipoly one.
If the OS map looks fine but you get distortions when converting it to tangent space, there is an issue with the conversion method you use.
Are you sure the skewmesh's shape is exactly the same as your lowpoly shape, silhouette-wise?
[ame]
Sometimes I bake in Modo though in order to make use of the round edge shader, and exploding a mesh is super easy with morph maps.
I wish SD had the option to convert the object space to tangent, then you could create a graph and automate a lot of things for all of your bake needs.