Crossfade LOD Transitions for Clutter Effects

[Dinorius_Redundicus]

I'm having a bit of trouble with the terminology being used. The article talks about materials in terms of polygon count. How can a material have polygons? I thought PBR was all about giving the impression of polygons and physical volume but using only 2D texture materials. As an eminent Queenslander once said "please explain".

[Shortline2]

That looks nice, if you can make it work on railroad tracks as well it would be even better ;-)

Linda

[n3vpolsen]

I'm having a bit of trouble with the terminology being used. The article talks about materials in terms of polygon count. How can a material have polygons? I thought PBR was all about giving the impression of polygons and physical volume but using only 2D texture materials. As an eminent Queenslander once said "please explain".

PBR (Physically Based Rendering) isn't about physical volume, that would be height maps / parallax effects. PBR uses emissive, roughness, ambient occlusion and metallic textures (all in one texture in our engine) to give a visual result based on lighting.

Height maps are used in parallax effects to give the perception of depth on (well "into") a polygon surface.

Regarding the reference to Materials in this crossfade blog, we are saying (with LOD0) one mesh or one part of the mesh will be UV'd with Material A and this part is made up of 500 polys. Another mesh or other part of the mesh will be UV'd with Material B and this part is made up of 100 polys. The meshes or parts of the mesh (however you decided to model your asset) must have 2 materials in LOD0 so the 500 polys with Material A can start off opaque and start to fade out as the 100 polys with Material B starts to fade in to create that smooth blend. It's also worth noting that you are only exporting 1 file from your modelling software, for example lod0.fbx which will contain all the polys and materials (500-A + 100-B)

[Dinorius_Redundicus]

Thanks for the high level overview. Remember that many in your audience are non-professional modellers, stuck in our old creation methods, maybe even still struggling to master them. I’m sure a lot of us are hearing about these new methods for the first time and at a rate of about one per week. It’s easy to get lost in the unfamiliar jargon and details. Seeing the big picture helps.

[martinvk]

Hope to see this extended to other materials as soon(tm) as possible. Once other objects get this smooth transition effect, I think the immersive experience will go up by several notches. Bravo

[PerRock]

Digging that new UI ... but I'm sure there are others here who hate it.

[Dinorius_Redundicus]

@n3vpolsen. I re-read your explanation a few times now, but I still don't get why the high- and low-poly incarnations of LOD0 need different materials.

It's the meshes that are cross-fading (right?), so wouldn't the transition look smoother if both meshes used exactly the same material as they cross-fade? Or are the materials A and B actually the same in appearance, but just given different names because the game has no other way to distinguish the high-poly mesh from its low-poly counterpart?

[EverTrainz]

LOD transitions don't seem as bothersome to me unless it's modeled grass/shrub meshes (covered by this Dev Diary) or track. Considering how frequently track is used, and how high the polygon count can reach, LOD is used rigorously, but the same amount of "rigor" is conveyed to our eyes as the LOD jumps between levels.

Therefore, I think crossfading should be implemented on track spline assets, perhaps in a manner that makes it easier on the creators of pre-existing track.

[pdkoester]

I think we are all going to miss the old popcorn effects, and need to learn to get accustomed to the new style.

[WindWalkr]

It's the meshes that are cross-fading (right?), so wouldn't the transition look smoother if both meshes used exactly the same material as they cross-fade? Or are the materials A and B actually the same in appearance, but just given different names because the game has no other way to distinguish the high-poly mesh from its low-poly counterpart?

The fade parameters are material attributes, so to have one set of polygons "fading in" while another set is "fading out" they must belong to different materials. We expect that the materials will likely be equivalent in all other ways.

chris

[WindWalkr]

Therefore, I think crossfading should be implemented on track spline assets, perhaps in a manner that makes it easier on the creators of pre-existing track.

We continue to investigate improved techniques in all aspects of the product, however I should stress that the technique discussed here actually INCREASES the polygon count and overdraw ratios of the high LOD models, so may not be appropriate for models which have very high polygon counts or which regularly occupy large parts of the screen. Additionally, different hardware has different performance outcomes with this material, meaning that this technique may need to be restricted to parts of the scene which can reasonably be turned off where it causes performance problems. This is true of clutter- turning it off causes you to lose some nice visuals, but won't ruin the gameplay. It's not true of track or other major parts of the scene.

It unfortunately isn't a case of "this looks great, let's use it on everything".

chris

[Scitimar]

The fade parameters are material attributes, so to have one set of polygons "fading in" while another set is "fading out" they must belong to different materials. We expect that the materials will likely be equivalent in all other ways.

chris

Is height and/or normal usable in the material ?

[WindWalkr]

Is height and/or normal usable in the material ?

Height, as in parallax displacement, is not present in this material.

The material does use a normal map and PBR parameters.

chris

[Scitimar]

Height, as in parallax displacement, is not present in this material.

The material does use a normal map and PBR parameters.

chris

Thank You, and that looks quite good.

[tfb]

What is the texture for Unknown Location: <kuid2:116296:16048:127> <kuid2:116296:16115:127>?