[Papervision3D] PV3d vs. Away3D - what the difference?BE SPECIFIC!

Sun Jul 5 01:11:18 PDT 2009

Hi Peter,

We might have a difference in definitions (and I've heard different people
use different terms), but here's my take from my years as a 3D engine
developer:

I'm not sure what you mean by bump maps being 1 dimensional displacement
above or below the surface. You may be referring to two things. In one case,
from a grayscale (1-dim) bump map, you can easily compute a 3-dim normal
map. You just need to compute the slopes in X and Y at each texel and do
some cross product magic. You end up with a normal map (which you explained
quite well). This is useful to save on texture memory (3x smaller) if you
can afford the extra computations at render time, and is easier for artists
to draw.

The second thing you may be referring to is displacement mapping, and is way
more powerful (and costly) than other techniques. It requires re-tesselating
your geometry in an adaptive way to create new vertices where needed and
displace them. You can start off from a base model, and end up with a very
detailed one by letting an artist simply draw his displacement map. If you
look at the model on the side, you'll see the detail of the geometry (which
you won't in normal mapping, as only the normal is modified).

To go back to the definitions, bump mapping generally refers to the whole
family of techniques to modify a geometry based on a map. Normal mapping is
one of them. Wikipedia explains this pretty well.

Cheers,

Antoine Azar
2XM Labs
645 Wellington W.
Montreal, Quebec
H3C 1T2, Canada
T. 514-606-4821
http://www.2xmlabs.com <http://www.2xmlabs.com/> 

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From: papervision3d-bounces at osflash.org
[mailto:papervision3d-bounces at osflash.org] On Behalf Of Peter Strømberg
Sent: Saturday, July 04, 2009 7:32 PM
To: papervision3d at osflash.org
Subject: Re: [Papervision3D] PV3d vs. Away3D - what the difference?BE
SPECIFIC!

With respect Antoine, and at the risk of sounding pedantic, those terms are
not entirely synonymous, and while
I'm sure you have a grasp of the different techniques I'll try and explain
the differences. 

For starters normal maps can be used for more than just texture.
While you can use normal maps on a model for "bumps", they are inherently 3
dimensional as appose to a bump maps 1 dimension.
That is to say they describe the direction of a pixel, contra it's (one
dimensional) displacement above or below a given surface.
While monochromatic bump maps create variation in a reference face during
lighting calcs, normals don't necessarily require a reference face and can
simulate geometry in a lighting model where no geometry exists at all.

To illustrate, here's a 2D image with a normal map applied. Because is
contains the direction of each pixel, 
it is possible to simulate lighting even though there is no geometry
involved whatsoever, or 3d engine for that matter.
http://www.videometry.net/ARdemo/normalMapper.html
(and the normal map used: http://www.videometry.net/ARdemo/norms.png)

Granted in that example the normals were pre-calculated from a 3d model,
so here's the same filter applied to a simple photograph of an empty room 
http://www.videometry.net/ARdemo/normalMapperRoom.html
(normal map drawn freehand in photoshop:
http://www.videometry.net/ARdemo/3dplacementRoom_norms.png)

How would you do that with a bump map?
While normal maps can do bump mapping, bump maps don't have enough info on
there own to calculate normals. 

Antoine Azar wrote: 

Nice demo, but to clarify what you say, normal mapping IS bump mapping. 

Antoine Azar
2XM Labs
645 Wellington W.
Montreal, Quebec
H3C 1T2, Canada
T. 514-606-4821
http://www.2xmlabs.com <http://www.2xmlabs.com/> 

On 3-Jul-09, at 2:44 PM, Peter Strømberg wrote:

There's one difference that hasn't been mentioned, but has proven to be of
paramount importance to me, 
at least for product presentation, and that is normal mapping. 
Away has it, PV does not yet, though I've heard it mentioned a few times.
http://away3d.com/away3d-normal-mapped-bust

Don't confuse this with bump mapping, as I've seen people do. Normal mapping
makes a low poly model 
look like a high poly model, and the only "hit" is an extra bitmap in the
materials stack.
While bump maps and normal maps can add detail, normal mapping has the
appearance to adding  geometry,
especially to large smooth, rounded surfaces, not to mention nipples.

For more info and examples google "Normal Mapping"

Cheers,
Pete(2)

andysk8er wrote: 

Okay, I have been researching this and I can't find a definitive answer.
What

is the main difference between PV3D and Away3D? Don't give me a bunch of

nebulous statements like "Papervision has more shaders" or "Away handles

Interactive materials better" or "PV is faster." What I really want to know

is this:

WHAT WAS EACH ENGINE BUILT FOR?

It looks like PV3D has a broad feature set that was intended mostly for

websites, applications and viewers.

Away looks like it was designed with making 3D games and game environments

in mind. 

Is this true or am I off the mark? I don't really care about things like

"Away has a torus as a native object." I'm really just curious which engine

fits a certain type of project better than another. If I have a project

spec, how can I decide which engine to use?

I'm not trying to start any arguments about the engines. I'm very familiar

with Papervision and have built several projects in it. I haven't used

Away3D, but I'm starting to think that a few of it's features may be helpful

for a game I am designing in my spare time. Any advice from anyone here?

Thanks,

Andy.

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