Parallax Occlusion Mapping Deep Dive Bonus Episode - Nanite vs POM

[@Ricky_Lauw]

A comprehensive decals series like this would also be great. There are some interesting caveats with that workflow in Unreal

[@TechArtAlex]

I've just started doing some decal videos to explore the new(ish) and powerful custom decal response feature.

[@that3dguy119]

Hey ! I was wondering if you knew more channels like yours that give such great explanations and deep dives. Most mainstream channels only cover beginner tuts. Its really hard to find goldmines like your channel, wonder if you knew any ?

[@TechArtAlex]

Some other good tech art channels off the top of my head are Tech Art Aid, Visual Tech Art, Martin Donald and PrismaticaDev. They all post pretty detailed and often fairly unique content.

[@monsterinsane2228]

awesome! thank you a lot for this!!! I really really love this series!

[@pauljojo1318]

You could probably save some more performance with the Nanite mesh by simplifying it in Unreal. The UE algorithm does a great job from my experience. I bet you could lower the poly count by a factor of 5-10 without losing much detail. From my experience nanite is very expensive with shadows. Depending on the use case I like to play around with the shadow variables in editor or even fake the shadows all together. On the other hand POM is very flexible performance wise and requires less storage space. Both have their purpose.

[@TechArtAlex]

It actually was, in order to give the best visual comparison, I started with a mesh that had 1 vertex per pixel, then decimated it. You'll notice some larger rocks have less dense polygons on the wireframe. But I left a lot so that Nanite could do its thing. Nanite is pretty efficient at drawing into VSM, but having two rendering paths when drawing shadows definitely isn't cheap at the end of the day. I suspect Nanite tesselation/ displacement will reduce the use cases of POM a lot - but it still has its benefits.

[@monsterinsane2228]

I really hope you'll able to cover the new substrate material from UE5.2 in the future as well

[@TechArtAlex]

I have been thinking about that.

[@TUSH4R451]

Your nanite mesh looks super sharp and detailed. Which software did you use to make it?

[@TechArtAlex]

Surprisingly it was authored in UE5 directly. I heavily subdivided the plane, baked in the displacement map, and then decimated the mesh back down. The built in modeling tools are not extensive, but for simple things it's a nice convenience not to have to jump between software.

[@Hotrood999]

Hey Alex do you think it is worth making a new video comparing POM vs nanite tessellation in unreal 5.3? I love your videos

[@TechArtAlex]

Probably, although I've heard it's pretty unstable right now so it may need more time for a fair comparison. When all the kinks are worked out, my hunch is it'll be better in most cases. But we shall see. Thanks!

[@marconapolitano2821]

well the only reason to use POM is if you want to do vertex paiting on a plane, or if you are making a landscape and you don't want to use virtual textures, also I have heard they were going to fix the PDO issue with self shadowing in a 2016 stream and i am still waiting 7 years later.

[@TechArtAlex]

There are some other use cases too, like POM decals, or just adding a bit more depth on certain assets. For example I've used POM on the chainmail of a character's armor and it significantly improved the apparent detail and depth, even though the amount of parallax it added was quite tiny. I have given up on them fixing PDO applying to the shadow depths, even though I have several use cases beyond POM that I would like it for. PDO also needs to be applied to velocity depths too but doesn't. Their implementation is kind of half baked.

[@DrTheRich]

Oh this is what i mean, how did you get the silhouettes here on the POM?? Have i missed this in the rest of the series?

[@TechArtAlex]

I don't think I explicitly mention it anywhere. I replied to your other comment but I'll post here too in case anyone sees it and is curious. I'm using the UV coordinates as a mask. Anything outside of the 0-1 range can be cut off. But you can also sample a mask texture if you need more complicated silhouettes.

[@DrTheRich]

@@TechArtAlex Thank you very much, i can finally make by brick wall corners look realistic

[@DistructiveElements]

Can you POM and Nanite mesh with micro-surface detail?

[@TechArtAlex]

You can use POM on a nanite mesh, but keep in mind that POM doesn't do well with non planar surfaces well unless the displacement is kept to an absolute minimum.

[@stephananemaat]

I have a feeling your POM shader would look visually superior than your displaced mesh in VR. When i experimented with it myself, my displaced mesh looked flatter than POM in VR. Probably one use case where POM is indespensible (for now anyway)

[@TechArtAlex]

Interesting, I haven't compared them in VR. I'll have to give that a try. Maybe it gives the per-pixel displacement more room to shine since the tiny differences in depth are more perceptible.

[@stephananemaat]

@@TechArtAlex yeah, probably the ideal use case for pom actually, since the two eyes each see a separate rendered image, hence a parallax effect

[@ArtTstudent]

you'd lose the flexibility of texture blending on terrain meshes when using Nanite. but Nanite has it's positives. trade offs to consider

[@TechArtAlex]

Yeah, there's almost always a trade off. I do think Nanite or a similar solution will eventually replace POM in basically all use cases, but we're not there yet.

[@ArtTstudent]

@@TechArtAlex some procedural/dynamic displacement with Nanite perhaps? otherwise, it's a pain to constantly swap Nanite meshes from stone/wood/grass biomes during set dressing. fixed mesh vs dynamic mesh perspective

[@TechArtAlex]

@@ArtTstudent They're experimenting with Nanite tesselation that will allow you to achieve results similar to if not better than the old landscape displacement system. It works in 5.3 but is hidden by default. Still pretty experimental.

[@ArtTstudent]

@@TechArtAlex i did not know at all. Thank you for sharing ~ looking forward

[@Hotrood999]

Nice

[@johnharbinger4637]

You cant compare performance on that scale, what would a 100 times larger parallax terrain using tile texture and vertex paint compare to both 100 nanite meshes as unique individual meshes and compared to 100 instanced nanite meshes, there's also now a new sudo instance allowing more variation so would also wonder how that works with nanite and performance at that scale.

[@TechArtAlex]

Not true. Both Nanite and POM cost scales primarily with pixel count, not instance count. That is why I'm zoomed in where the material has full screen coverage. Tiling the material 100x over a giant mesh or having 100x as many Nanite meshes using the same material would have no difference in performance.

[@johnharbinger4637]

@@TechArtAlex thanks for clarifying

[@TechArtAlex]

@@johnharbinger4637 Sure thing! Thanks for watching

[@Rlador]

POM can work together with Tri-Planar.

[@TechArtAlex]

Sure, although normally this means doing POM three times so it can get pretty expensive. It also often has issues at the transition points because there's no guarantee of an intersection between the blended projections height values at these points, resulting in artifacts. I may do a video on this in the future, but I've been busy lately. Thanks for watching.

[@Rlador]

@@TechArtAlex Usually there is no need for 3 projections. Often 1-2 sides are needed. I could not completely make one side customizable so that I could change its position.

[@yoshedev5290]

I'm looking into trying to get this to work now. Do either of you have an example that could be shown? I have I only gotten it to work on my walls so far, but can't figure out how to get it working for the floors and ceilings as well. Inexperienced here so I am in a bit over my head trying to figure out tri-planar + POM together