chris512

Volumetric Fog in P3D 3.1

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I have a question for the tech experts on P3D...

 

If I deselect the Volumetric Fog option in P3D, does this mean that the clouds are non volumetric too? Or are they still volumetric with this option set to off?

 

The reason I ask is that turning off volumetric fog makes my sim so much smoother...

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The clouds never are volumetric. They are flat sprites. The fog is volumetric with that setting on. And yes, turning that option on can hurt performance if your computer isn't the fastest.

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The clouds never are volumetric. They are flat sprites.

 

Oh, I thought that with ASN and P3D the clouds were now 3D? They certainly don't seem to rotate like the old FSX clouds used to...

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Oh, I thought that with ASN and P3D the clouds were now 3D? They certainly don't seem to rotate like the old FSX clouds used to...

 

No, they aren't and btw ASN has nothing to do with the cloud textures (or 2D/3D) anyway. I see my clouds still rotating... unfortunately. I have to add though that during regular flying things look pretty okay and real. :wink: (I am using the free HDE v2 clouds btw because the default clouds aren't that good imho. It's a single cumulus.bmp that makes a world of difference.)

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Yeah I know that ASN doesn't come with cloud textures... I installed REX and Soft Clouds. They do a pretty good job if that's the case. I can remember seeing clouds rotating as they passed the left hand window in the NGX on FSX, I don't ever see that now. 

 

I was held at 14000 in the Concorde X today and I was surfing the clouds for about 15 minutes. It looked amazing. Now I've disabled Volumetric Fog, the micro stuttering has gone too...

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The clouds never are volumetric. They are flat sprites.

 

Nope, sorry.

Clouds in FS are not sprites. They are 3D in the sense that they are two dimensional objects placed within a world of 3 dimensional coordinates.

"Sprites" are always 2D.

 

Potroh

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I have ASN and soft clouds and have posted dozens and dozens of screen shots on the P3D forums on Facebook, and the clouds look awesome.  This is with a 3+ year old , middle of the road desktop with an i5. 

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Nope, sorry.

Clouds in FS are not sprites. They are 3D in the sense that they are two dimensional objects placed within a world of 3 dimensional coordinates.

"Sprites" are always 2D.

 

Potroh

I probably stand corrected but they look like sprites to me anyway (when I am close to them and see them rotate). ;)

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Is that what we call volumetric fog ? :

 

24107384263_68883b775c_b_d.jpg

 

24734234025_975e21e314_b_d.jpg

 

Another topic : concerning rotating cloud, I had a lot and see them at every corner. Very annoying. With 3.0 and 3.1 and maybe a different set of texture with REX4 Texture direct and Soft Clouds and I haven't them anymore.

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They are sprites always have been

 

You guys are splitting hairs on terminology. Basically, the clouds in FSX/P3d are "2.5D". The clouds are composed of a series of  vertical planes (2D) in a 3D space (as noted above), which have been referred to as "sprites" for as long as I remember. The autogen trees are another example of 2.5D objects.

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Nope, sorry.

Clouds in FS are not sprites. They are 3D in the sense that they are two dimensional objects placed within a world of 3 dimensional coordinates.

"Sprites" are always 2D.

 

Potroh

 

Clouds are sprites and they do rotate.  That hasn't changed since FS2002. 

 

Like Jay said, they are kinda 2.5D...a bunch of 2D sprites placed in a group to make them look 3D, and they rotate to keep that "3D volume" illusion.

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You guys are splitting hairs on terminology. Basically, the clouds in FSX/P3d are "2.5D". The clouds are composed of a series of vertical planes (2D) in a 3D space (as noted above), which have been referred to as "sprites" for as long as I remember. The autogen trees are another example of 2.5D objects.

 

You are perhaps right and it's just a matter of correct terminology.

Sprite: "In computer graphics a sprite is a two-dimensional image or animation that is integrated into a larger scene."

 

I more than agree with the 2.5D definition, but sprites? No. Because in case of those clouds the only 2D elements are the bitmaps stitched into a 3D "frame" or "net", and bitmaps are definitely not sprites...

BTW, those bitmaps are anything but just vertical.

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Well, they call them sprites in SDK (Learning Center.chm) ... to quote:

 

 

 

Setup Scene Rollout
This Rollout deals with the preparation of the scene for the creation of clouds. Open the CumulusCongestus48-1.max file (it is located in the Modeling SDK/3DSM7/samples/clouds folder). This file was used to create one of the actual variations of Cumulus Congestus clouds at 4/8 coverage. At first glance, it looks a little odd. There is a cloud and a whole bunch of brightly colored boxes. The brightly colored boxes are used to create the cloud shape. The cloud shape consists of many smaller facing sprites or planes, which creates the volumetric feel of the clouds.
 
On the Setup Scene Rollout, click the Hide the Boxes! button. Now you can see the cloud all by itself. Next click the Select All Sprites! button. Notice that all of the cloud sprites are selected. This comes in handy when you want to move, rotate or scale the entire cloud. Now click the Clear Old Sprites! button. This will remove all of the existing cloud sprites. Your scene should now be virtually empty except for the camera and the bounding box. Click the Unhide the Boxes! button. Now you can see all of the boxes that were used to create the cloud. You are now ready to re-create the cloud using the Create Cloud rollout.
Setup Cloud Groups Rollout

The Setup Cloud Groups rollout is used to do two things: define Cloud Groups and limit Cloud Rotation. Currently, Cloud Groups are used for dynamically fading clouds in and out when the weather changes. They fade clouds out based on smaller units, rather than just the whole 16km x 16km block of clouds. All sprites must be associated with a cloud group or you will get an error when you try to export.

 

To create Cloud Groups, select a small batch of sprites that would reasonably make up a small cloud. Then press the Assign to Selected button next to the Cloud Group Number text box. It will put the following text in the User Defined Properties of the selected sprites: Cloudgroup = 0. It will also increment the Cloud Group Number text box by 1. This allows you to quickly assign Cloud Groups without having to type in a new number each time.

When sprites are displayed they default to a full 360 degree random rotation. This allows you to use less textures and get more variation. If you want to limit the rotation of a sprite (especially for the Base textures), use the Cloud Rotation text box to do so. If you name a box Base* when creating the cloud, it will automatically put Rotation=5 into the User Defined Properties of all the sprites created within that box. This means that the sprite will never rotate more than +5 or -5 degrees from 0 degrees. A 0 degree rotation means that when a sprite is facing you, the top of the texture will always be pointing up:

 

Also provides tips on how to setup clouds to minimize rotation.

 

True "Volumetric" clouds have a very high performance overhead (think of the FX system when I loads up one's screen with prop wash from snow/rain and how that impacts performance, now take that small local sample and apply it to 200+ mi radius and many more instances ... think in terms of minutes per frame to render rather than frames per second) ... the cloud/weather system in P3D IMHO is the best cloud/weather system I've ever seen in a flight/combat simulator.  It's definitely a compromise, but it's a very good compromise.

 

Cheers, Rob.

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Well, they call them sprites in SDK (Learning Center.chm) ... to quote:

 

Yes, the SDK names them as sprites.

Nevertheless, technically speaking they are actual 3D objects (just as the gmax example file shows in the FSX SDK) which are FILLED by 2D objects (sprites) but we might name them many other things.

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Yes, the SDK names them as sprites.

Nevertheless, technically speaking they are actual 3D objects (just as the gmax example file shows in the FSX SDK) which are FILLED by 2D objects (sprites) but we might name them many other things.

 

I suppose that might just be one of those things that they've named wrong. The term "bump map" is incorrectly used in FSX. The correct name is actually "normal map."

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Yes it's a "Group" of 2D planes ... but I suppose technically there really is no such thing as a 3D object in a two axis physical display (one's monitor) ... so we're sorta just dancing around "relative" definitions.

 

In order to do a "volumetric" cloud it would need to operate as a solid and no flight sim does solid modeling for obvious reasons.

 

Cheers, Rob.

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I'm getting slightly lost in the semantics of this thread but perhaps someone could avail us all of a simple answer? Is the use of volumetric fog an fps killer or is it purely GPU-specific?

 

Regards,

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David,

 

Every option you enable in the graphics settings will have some performance impact and that degree of impact will vary based on CPU/GPU used.  

 

The best answer I can give (don't know if it's deemed simple or not) is to experiment ... no harm in turning it OFF and see what it does, see if you notice the visual difference and if that visual difference to performance hit ratio is significant for you.  Everything about graphics settings is a "balance" and only you can determine the best balance.

 

There is no "magic" setting ... it's all a compromise from high end PC to low end PC.  Most of "FPS" killers I have are all exclusively 3rd party content (aircraft, scenery, AI, etc.) ... that's where I focus most of my performance tuning attention at.

 

Cheers, Rob.

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Intuitive and much appreciated answer Rob. The reasoning behind the question was that - although I have no problems with fps or 'blurries' etc., and am perfectly happy with the way that my setup runs - I was wondering if the selection of Volumetric Fog might have been tying up CPU/GPU resources that could best be utilised elsewhere in the running of the sim?

 

Regards,

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I'm getting slightly lost in the semantics of this thread but perhaps someone could avail us all of a simple answer? Is the use of volumetric fog an fps killer or is it purely GPU-specific?

 

Thanks David, I was beginning to wonder what I'd started! 


 

 


Is that what we call volumetric fog ? :

 

Vincent, that top picture you posted looks amazing!


 

 


There is no "magic" setting ... it's all a compromise from high end PC to low end PC.

 

I was hoping you might chime in Rob. The top picture Vincent posted of the external Cessna view is a good example of the endless battle I have with my Sim. I get it running great and then someone posts a picture and I think "I want that!" At which point I crank up the settings, and it all starts again!  :smile:

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Yes it's a "Group" of 2D planes ... but I suppose technically there really is no such thing as a 3D object in a two axis physical display (one's monitor) ... so we're sorta just dancing around "relative" definitions.

 

With due respect Rob, if you say "there's is no such a thing as a 3D object", you merely mix up the final physical display result (the end user's depiction) with the original 3D object, which is indeed done around X,Y,Z therefore 3D, regardless if it is rendered onto a 2D flat surface or a 3D hologram.

A 3D object is what is designed in X,Y,Z. A photo is 2D where no 3 axes exist...
A 3D object is a 3D object, designed in 3D by 3D designers, there's little use to argue that on the pure semantic level. If there were no 3D objects in a flightsim, we (the designers) would be in a very easy position...

Potroh

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A 3D object is what is designed in X,Y,Z. A photo is 2D where no 3 axes exist...

 

Think about that ... a photo is a snapshot of real world 3D objects ... a 2D coordinate system (the monitor) is doing it's best to depict  3D objects whether they are rendered or photo realistic ... but they are not true 3D objects.  A true 3D object is this keyboard I'm typing this response on ... my monitor is a 3D object that is projecting a 2D space.  I was primarily responding to the use of "technically" ... a 3D movie is not really 3D, it's recorded and presented in such a way as to "fool" the eye.

 

So for accuracy, a 2D space is being used to depict a 3D object, but it is not "technically" a 3D object.  I'm not debating this for the sake of argument (even though I'm sure it appears that way), but the word "technically" was used.  I personally think it's important to understand ... there is only a true X and Y which everything being rendered must resolve to ... this is important because it's that resolving from 3D virtual space to 2D real space that produces inaccuracy (precision issues) and introduces some of the oddities we see in flight simulators.

 

Cheers, Rob.

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Haha, Rob, when the holographic monitors come to market, I'm positive that you will be the first to post here on how to make it work with P3d. :wink:

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