Outside and doom3 engine / unrelated hdr question

[101998]

How would the doom3 engine render a large outdoor area, like say Far Cry(maybe that is a bad example, but general outdoorzy places)? I recall reading that the engine could support up to a 2mile area, but how would that work? With all the plants and stuff creating shadows all over the place would that not be extremely taxing on the video card? I was just thinking about the various games coming out using the engine and was just curious.


Unrelated hdr question (maybe I should make two posts) :

With the displays that are currently available in the consumer market could you see a difference between fp16hdr and ps2.0 hdr? I was under the impression that fp16 would allow more accurate brightness scales but that our current displays could not properly display the differences (ie you would need a monitor with 50k:1 contrast ratio to take see the superior rendering). The reason I ask is because rthdribl can do some pretty snazzy effects w/ ps2.0, and once again I was curious and you guys seem pretty “in the know” about these kinds of things.

 

[Neeyik]

How would the doom3 engine render a large outdoor area, like say Far Cry(maybe that is a bad example, but general outdoorzy places)? I recall reading that the engine could support up to a 2mile area, but how would that work? With all the plants and stuff creating shadows all over the place would that not be extremely taxing on the video card?.

Ask yourself this question - could you see anything, in real life, that far away? Would you notice the shadow a tree makes 500m away? Would you be able to spot difference plants within a field 300m away? The trick with all outdoor rendering is LOD (and in the case of Far Cry, changing 3D models into 2D sprites).

 

[Sage]

How would the doom3 engine render a large outdoor area, like say Far Cry(maybe that is a bad example, but general outdoorzy places)? I recall reading that the engine could support up to a 2mile area, but how would that work? With all the plants and stuff creating shadows all over the place would that not be extremely taxing on the video card?.

Ask yourself this question - could you see anything, in real life, that far away? Would you notice the shadow a tree makes 500m away? Would you be able to spot difference plants within a field 300m away? The trick with all outdoor rendering is LOD (and in the case of Far Cry, changing 3D models into 2D sprites).

ever fly small airplanes, Neeyik? It's amazing how much detail you can see at what distances once you get up just a tiny bit (that's assuming the country, not smog-filled city). But yes, LOD... just don't cut out too much with it. Of course, I'd say that currently the physical properties of the monitors are the most limiting for very small objects

 

[Sigma]

About HDR.

Can someone try, with a 6800, to mess around with Doom3 variables "r_hdr_*". It problably anables writting and blending to a FP color buffer and that is nice and the IQ should improve a lot...

 

[SteveHill]

About HDR.

Can someone try, with a 6800, to mess around with Doom3 variables "r_hdr_*". It problably anables writting and blending to a FP color buffer and that is nice and the IQ should improve a lot...

My current guess is that these cvars are used by the "exp" (experimental) rendering path. The game crashed for me when I tried switching to that path (r_renderer "exp") and I've yet to investigate the cause -- perhaps some stuff has been removed or nulled for retail.

 

[Richard]

As far as we know, HDR is used in the ARB2 path.

http://www.webdog.org/cgi-bin/finger.plm?id=1

 

[T2k]

How would the doom3 engine render a large outdoor area, like say Far Cry(maybe that is a bad example, but general outdoorzy places)? I recall reading that the engine could support up to a 2mile area, but how would that work? With all the plants and stuff creating shadows all over the place would that not be extremely taxing on the video card?.

Ask yourself this question - could you see anything, in real life, that far away? Would you notice the shadow a tree makes 500m away? Would you be able to spot difference plants within a field 300m away? The trick with all outdoor rendering is LOD (and in the case of Far Cry, changing 3D models into 2D sprites).

Actually I think it's amazing how many small details could be spotted even from a top of hill, for example...

 

[SteveHill]

As far as we know, HDR is used in the ARB2 path.
http://www.webdog.org/cgi-bin/finger.plm?id=1

Ahah, well that's really more about high-precision intermediate storage than high dynamic range lighting (which I couldn't see any direct evidence of in the main "interaction" shader). The cvars mentioned -- exposure control, bloom and so on, which apply to true HDR -- also don't appear to have any effect on rendering with the arb2 path, so that's what leads me to believe that they're part of "exp".

NB: There's also a Cg path, but it's not fully functional -- not surprising really as the exe refers to a couple of missing .cg files.

 

[KimB]

Ahah, well that's really more about high-precision intermediate storage than high dynamic range lighting (which I couldn't see any direct evidence of in the main "interaction" shader).

Actually, this is the first form of HDR lighting. In fixed-point precision, it requires first dividing the colors by some fixed amount, doing the calculations, then multiplying them (though you can bake the initial division either into the textures or into the lightsources). This basically prevents overflow, but results in banding on hardware with less precision.

But you're right, it's nothing compared to the more real HDR rendering that comes from using a floating-point framebuffer.

 

[SteveHill]

Actually, this is the first form of HDR lighting. In fixed-point precision, it requires first dividing the colors by some fixed amount, doing the calculations, then multiplying them (though you can bake the initial division either into the textures or into the lightsources). This basically prevents overflow, but results in banding on hardware with less precision.

Absolutely, that's precisely why I chose my words carefully when I said "I couldn't see any direct evidence" because the lights could be pre-scaled.

 

[London Geezer]

you would need a monitor with 50k:1 contrast ratio to take see the superior rendering

Yeah, and then, after u're blind, it will look the same as when it's off! Cool huh!?

 

[JD]

Well, the whole outdoor area would firstly be done at dark. No sun or directional light because it would cast too many shadows. It's a portal engine and the areas would have to be small and connected with portals. You can't put too many lights in the frustum because of the shadows. You basically could do a DeusEx style game with it, no gta3 style game. The plants would either have to use projected shadows or shadow maps because of holes in the plants. Same thing with fences, grilles, etc. You could fake it like in FarCry and use cubemap projected shadows though. The thing with FarCry is that for outdoors they use traditional lightmapping meaning static lighting. Only in indoors do they use doom3 lighting and they cheat as well. I don't think their light travels across portals or vis areas. Ok, as you can see, engines are specifically made for a game. In future I think engines will become more general because of the horsepower of the hw that will allow us to forgo some restrictive things we're faced with now.

I forgot to say that you'll need to add ambient for outdoors and cut down on the number of shadows you're creating. Say you're looking outside a window and are seeing lots of buildings and trees, etc. I think Chaser guys did something similar. But basically, few lights and shadows is the constraint you're faced with.

 

[pc999]

See this http://www.beyond3d.com/forum/viewtopic.php?t=14469&start=0

I could share a small additional info about the shot.. All shadows in the scene are dynamic & rendered real-time, and all objects (even a straw off grass) cast one shadow for each lightsource (in the shot there are 3 light sources). Oh, and everything is of course self-shadowed too.

 

[KimB]

Well, the whole outdoor area would firstly be done at dark. No sun or directional light because it would cast too many shadows.

Nah, as a previous poster stated, it's all about LOD. You turn shadows on at some distance, reduce polygon detail at some distance, etc.

City of Heroes, for instance, appears to have stencil shadows in its huge outdoor zones, but it turns them on at a certain distance (and appears to only have them for static objects, unfortunately...I bet the shadow hulls are pre-computed).

 

[Ante P]

Well, the whole outdoor area would firstly be done at dark. No sun or directional light because it would cast too many shadows.

Nah, as a previous poster stated, it's all about LOD. You turn shadows on at some distance, reduce polygon detail at some distance, etc..

If you reduce polygon counts in doom 3 there won't be any models left

 

[tEd]

Well, the whole outdoor area would firstly be done at dark. No sun or directional light because it would cast too many shadows.

Nah, as a previous poster stated, it's all about LOD. You turn shadows on at some distance, reduce polygon detail at some distance, etc..

If you reduce polygon counts in doom 3 there won't be any models left

stick-figures with bump-mapping