Celestia Forums

This is not in bugs because I don't know yet if it's my graphic card or Celestia or something else.

When using Celestia with virtual textures, noticed something strange.
Between the textures, there is a seam visible.

Heard something about Direct X 11 having something to get rid of this kind of seams.

Is OpenGL also getting this?
And will Celestia use this?

Could somebody please answer these questions?

Could you provide an example?

What VT are you viewing?
Which version of Celestia?
Please include a Cel URL, too.

I'm seeing seams with Celestia v1.5 with BMNG earth texture.
Between every texture, there was a line visible.

That is the problem of the graphic cards, not celestia.

My question was about when the OpenGL/DirectX specification would have ATI/Nvidia make cards that don't have that problem any more.
I'm now reproducing the problem in Celestia v1.6.
However I'm getting a lot of new weird stuff.

One very important thing.
My X1600 Graphic card has partially melted because of a bad Windows Vista 32bit Home Premium driver!!

The seams aren't related to that.






(See the texture edges messing up in this image?)

Another three images.

(These bodies don't have any addons or modifications.)
This is done with Celestia v1.6.

This is the moon.


This is a closer look to the moon. See the edges not closing in on each other correctly?


A view on Titan.
cel://Follow/Sol:Saturn:Titan/2009-08-05T18:57:43.93901?x=GHD4nfCRYw&y=lL8K04nKu////////////w&z=bFRZXFo0ov///////////w&ow=0.427154&ox=-0.318739&oy=-0.839774&oz=0.10356&fov=25.9979&ts=1&ltd=0&p=0&rf=21251&lm=2048&tsrc=0&ver=3

What version of Catalyst do you have installed?

I'm sorry to agree that it seems to be an ATI graphics card and driver issue, since I see nothing like the problems you indicate when using computers using two different types of Nvidia cards.

There was a post a little while ago by sgmccabe, who had better results after reverting to Catalyst v8.4.
See viewtopic.php?f=3&t=14000&p=116584&hilit=catalyst#p116584

It is that problem, and I have checked it.
Resized textures to 1K and it worked!
EDIT: Have Catalyst 9.3 installed.




However there is still a seam in the images.
Is this because of the texture or something in OpenGL not properly aligning?

According to the AMD web site, Catalyst driver v9.6 does *NOT* support the X1600. v9.3 was the last one for that card.

See http://support.amd.com/us/gpudownload/w ... ng=English

Oops, it' s Catalyst version 9.3.
Best version 8.4, now I know.

What about the aligning of the texture?

These seams are a known issue and was discussed at CM. Here is a link about where the discussion starts.
http://forum.celestialmatters.org/viewt ... =1966#1966
Here is where I showed a few examples.
http://forum.celestialmatters.org/viewt ... =2004#2004
There was a bug reported about this but it's still open.
http://forum.celestialmatters.org/viewt ... =2765#2765
I'm not sure but it looks like this will be addressed in a future release of Celestia.
Resolution = postponed
cartrite

That's unfortunate.

Hopefully OpenGL will help.
OpenGL has two very interesting new features in 3.2 related to this problem :

# Shader Fragment coordinate convention control
# Seamless cube map filtering

Hopefully those two will somewhat solve the seams.
Or provide a good way to get rid of the seams.

Other interesting features for Celestia in general and Celestia' s VT' s:
# Fragment depth clamping
# Multisampled textures and texture samples for specific sample locations

(there is more new stuff in OpenGL 3.2)
# Geometry Shader support
...

Source:
http://en.wikipedia.org/wiki/OpenGL#OpenGL_3.2

Some url's

(OpenGL 3.2 doesn't support an ARB tessellation.)

https://www.opengl.org/news/comments/use-tessellation-in-opengl-to-render-at-6-times-the-speed/

Seamless cube map filtering is a very useful feature, but it won't help with the seams between virtual texture tiles. They're just regular 2D texture maps, not cube maps.

The seams between tiles are caused by the fact that bilinear interpolation (smoothing) between the pixels of a texture only works within a texture tile. To eliminate the seams, it's necessary to have some overlap in the texture tiles. The tools to generate the virtual textures could do this... If you're using 512x512 tiles, the tool would resample the input texture tile to 510x510 and set the center texture. The pixels at the edge of the texture would be copied from adjacent tiles. Some support within Celestia is also required, as the texture coordinates need to be adjusted slightly.

So, the seams are a solvable problem, but not trivially solvable.

--Chris

duds26 wrote:It is that problem, and I have checked it.
Resized textures to 1K and it worked!
EDIT: Have Catalyst 9.3 installed.

Celestia_Weird_Effect_On_Melted_ATI_X1600_pic7.jpg

However there is still a seam in the images.
Is this because of the texture or something in OpenGL not properly aligning?

Celestia_Weird_Effect_On_Melted_ATI_X1600_pic8.jpg

duds26 image EARTH ?

EARTH.jpg ? 1K

1K texture = 1024*512

Resized the earth texture in the hires folder.
C:\Program Files\Celestia\textures\hires\
(Windows Vista Home Premium 32 bit.)

Resized earth texture from 2048*1024 to 1024*512