What is/causes texture crawling ?

In article <eg0dk0$o13$1@news5.zwoll1.ov.home.nl>, Skybuck Flying
says...
> Hello,
>
> When I play Battlefield 2 and fly with a helichopter the terrain seems to
> "crawl".
>
> For example hills seem to deform.
>
> This is known as "texture crawling".
>
No, that's not texture crawling. Texture crawling is when you get a
pattern of dots around the edges.


--
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 >> Stay informed about: What is/causes texture crawling ? 

Skybuck Flying wrote:
> Hello,
>
> When I play Battlefield 2 and fly with a helichopter the terrain seems to
> "crawl".
>
> For example hills seem to deform.
>
> This is known as "texture crawling".
>
> What causes it ?
>
> What can be done about it ?
>
> Bye,
> Skybuck.
>
>

I believe you are mislabeling:

We were discussing texture-aliasing, the correct term for "Texture
Crawling" as it pertains to flight sims. This is when textures, of a non
uniform color, rapidly flip change colors at a pixel level as you move
closer, or away from them.

This is due to driver optimizations,specifically Trilinear optimizations
and inadequate anisotropic filtering being applied and lod bias not
being clamped when FSAA is applied.

BF2 gives the best image when run at high resolutions, gamma corrected
super sampling enabled (via the nvidia control panel), trilinear
filtering on, lod bias clamped, and anisotropic filtering set at 8x.

These settings eliminate, completely, textural artifacts.
However...always a however, what you are describing when you say "the
hills seem to deform" is terrain morphing.

As you approach a terrain mesh, the wire frame of the landspace without
any textures on it, the apparent distance between triangle vertices
increases. What appeared as a gentle slope from far away now appears as
an unnatural diagonal line. To compensate for this, the terrain deforms
and adds more vertexes as you approach, to maintain the illusion of
smoothness.

Perhaps your view distance setting is too low? Try to increase it and
see what happens!
 >> Stay informed about: What is/causes texture crawling ? 

My take on this is that the flying over the landscape is a heavy video load
on the video card, and it is overtaxed/overheating. You did not say what
card OR what game video settings you are using.

--
DaveW

----------------
"Skybuck Flying" <spam RemoveThis @hotmail.com> wrote in message
news:eg0dk0$o13$1@news5.zwoll1.ov.home.nl...
> Hello,
>
> When I play Battlefield 2 and fly with a helichopter the terrain seems to
> "crawl".
>
> For example hills seem to deform.
>
> This is known as "texture crawling".
>
> What causes it ?
>
> What can be done about it ?
>
> Bye,
> Skybuck.
>
 >> Stay informed about: What is/causes texture crawling ? 

"Mr.E Solved!" <Iamsingle RemoveThis @askme.out> wrote in message
news:c_WdnQfg_P0Ik7nYnZ2dnUVZ_rednZ2d@comcast.com...
> Skybuck Flying wrote:
>> Hello,
>>
>> When I play Battlefield 2 and fly with a helichopter the terrain seems to
>> "crawl".
>>
>> For example hills seem to deform.
>>
>> This is known as "texture crawling".
>>
>> What causes it ?
>>
>> What can be done about it ?
>>
>> Bye,
>> Skybuck.
>
> I believe you are mislabeling:
>
> We were discussing texture-aliasing, the correct term for "Texture
> Crawling" as it pertains to flight sims. This is when textures, of a non
> uniform color, rapidly flip change colors at a pixel level as you move
> closer, or away from them.
>
> This is due to driver optimizations,specifically Trilinear optimizations
> and inadequate anisotropic filtering being applied and lod bias not being
> clamped when FSAA is applied.
>
> BF2 gives the best image when run at high resolutions, gamma corrected
> super sampling enabled (via the nvidia control panel), trilinear filtering
> on, lod bias clamped, and anisotropic filtering set at 8x.
>
> These settings eliminate, completely, textural artifacts. However...always
> a however, what you are describing when you say "the hills seem to deform"
> is terrain morphing.
>
> As you approach a terrain mesh, the wire frame of the landspace without
> any textures on it, the apparent distance between triangle vertices
> increases. What appeared as a gentle slope from far away now appears as an
> unnatural diagonal line. To compensate for this, the terrain deforms and
> adds more vertexes as you approach, to maintain the illusion of
> smoothness.
>
> Perhaps your view distance setting is too low? Try to increase it and see
> what happens!

Ok, I will assume the "hill deforms" are caused by vertices missing or
vertices being added.

I have some further questions about this:

1. Does the game itself remove or add vertices ?

2. Does the opengl/directx or video driver remove or add vertices ?

Bye,
Skybuck.
 >> Stay informed about: What is/causes texture crawling ? 

Skybuck Flying wrote:

> Ok, I will assume the "hill deforms" are caused by vertices missing or
> vertices being added.
>
> I have some further questions about this:
>
> 1. Does the game itself remove or add vertices ?
>
> 2. Does the opengl/directx or video driver remove or add vertices ?
>
> Bye,
> Skybuck.

Correct, the deformation in the terrain is a function of the game
engine. The designers needed to minimize some of the complexity, in
certain views, to either reduce polygon count, or lessen the load of
processing textures that you weren't really going to pay attention to.
The farthest textures and models are, rightly, the first to go, since
you likely not paying much attention to them, and it's intuitive to lose
detail the farther you are from the object.

You can also morph (change the shape, but not the number of vertices)
terrain for visual effect as well...crater damage, earth movers, etc. IT
doesn't have to be just about improving frame rates.

The creation of terrain triangles, in wire frame form, is one of the
first steps in a 3D rendering of a scene. This is generally known as
'defining primitives'. While your hardware can speed this process up, it
is the game program that determines where and how many there will be. So
no, your graphics API (In this case Direct3D, part of DirectX 9.0c) is
not determining how to deform your terrain.

To prevent this and "pop-up" an extreme form of terrain deformation, you
must increase your view distance as far as possible, at the highest
resolution possible. Which has it's own issues...
 >> Stay informed about: What is/causes texture crawling ? 

> Correct, the deformation in the terrain is a function of the game
> engine. The designers needed to minimize some of the complexity, in
> certain views, to either reduce polygon count, or lessen the load of
> processing textures that you weren't really going to pay attention to.
> The farthest textures and models are, rightly, the first to go, since
> you likely not paying much attention to them, and it's intuitive to lose
> detail the farther you are from the object.
>
> You can also morph (change the shape, but not the number of vertices)
> terrain for visual effect as well...crater damage, earth movers, etc. IT
> doesn't have to be just about improving frame rates.
>
> The creation of terrain triangles, in wire frame form, is one of the
> first steps in a 3D rendering of a scene. This is generally known as
> 'defining primitives'. While your hardware can speed this process up, it
> is the game program that determines where and how many there will be. So
> no, your graphics API (In this case Direct3D, part of DirectX 9.0c) is
> not determining how to deform your terrain.
>
> To prevent this and "pop-up" an extreme form of terrain deformation, you
> must increase your view distance as far as possible, at the highest
> resolution possible. Which has it's own issues...

This seems contradictional to your previous post in which you adviced
to tweak driver settings for better visual quality.

How do you explain this contradiction ?

Bye,
Skybuck.
 >> Stay informed about: What is/causes texture crawling ? 

Skybuck wrote:

> This seems contradictional to your previous post in which you adviced
> to tweak driver settings for better visual quality.
>
> How do you explain this contradiction ?
>
> Bye,
> Skybuck.


There isn't one. Read again, carefully. Best of luck to you.
 >> Stay informed about: What is/causes texture crawling ?