Very weird VT behaviour

General discussion about Celestia that doesn't fit into other forums.
Topic author
rthorvald
Posts: 1223
Joined: 20.10.2003
With us: 21 years 1 month
Location: Norway

Very weird VT behaviour

Post #1by rthorvald » 29.09.2004, 21:53

Hum.
I am working on getting down to the "surface" of a gas giant in my Ran system, and are building a virtual texture that will go to level 10.

However, i have noticed something very strange: with the tilesize set to 512, Celestia refuses to load tiles above Level 3. Setting the CTX tilesize to a smaller value (say 256) lets Celestia load higher levels. Setting the CTX to a tilesize of 64 lets me view Level 7 textures, but beyond that nothing shows up.

What is really weird is that i do NOT have this problem with the terrestrial world where i am down to Level 9, with the CTX tilesize set to 512! This fact should rule out a memory problem.

So, what might be going on here? Is it something to do with the radius (size) of the gas giant? It?s?the only difference i can think of - it is at least 10 times the size of the terrestrial.

Oh, i discovered the Oblateness Bug, and set oblateness to 0. That?s not it. Also, both texture sets are JPGs at 512x512.

If anyone has a suggestion, please respond...

-rthorvald

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selden
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Location: NY, USA

Post #2by selden » 29.09.2004, 22:16

Have you tried using your deeper VT on the gas giant?

I just now tried the BlueMarble DDS VT on Saturn and it seemed to work OK.
Selden

Topic author
rthorvald
Posts: 1223
Joined: 20.10.2003
With us: 21 years 1 month
Location: Norway

Post #3by rthorvald » 30.09.2004, 12:00

selden wrote:Have you tried using your deeper VT on the gas giant?


Yes, tried it now. It seems i can load higher levels with that one, without changing the tilesize value. That does not make sense, as the two texture sets are produced in the exact same way.

Also, if i shrink the radius, it seem to load more tile levels...

Now i?m starting to doubt my machine. How does memory work with VTs? Does it use Ram or Vram to calculate and position the tiles, and is there a key for how much memory is needed to load what?

BTW, i use an ATI Radeon 7500 with 32 MB Vram. 768 MB ram.

-rthorvald


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