Celestia Forums

http://www.nvidia.com/view.asp?IO=earthviewer

anyone with an nvidia card should try that out.

instead of having one large texture (8K by ...) for a planet, why not divide up the textures.

on earthviewer, I can zoom down to the street level and see houses.

the idea is sort of like the model LOD code that Intel created (less polys further away, more closer up.)

in this case, when you're far out, you can use something like a 512x384 or so texture for the surface of earth, and then start loading more detailed textures as you get closer (IE: the next level down gets loaded as you get into the current level.) that way, all you're doing is swapping textures in and out of memory. older cards could (theoretically) benefit from this.

this would probably be very difficult to implement, so I don't expect it to happen, but it is food for thought...

Of course it would be cool but i'll tell you why it's not a great idea:

-Bandwidth: As you are approaching a planet you'd have to be constantly uploading new textures to the graphics card. And this is slow, you'd have a hard time getting decent framerates. Same would happen with a rotating planet (fast pace) from a close view.

-Storage: We're talking about hundreds of MB worth of storage just for a planet. Even if compressed the whole Earth at 1m/pixel (enough so you could see trees or houses) can take several GB.


There's no doubt we'll be able to do it in a few years but today that's just a dream. A nice dream though

Hi,

I tried it. Pretty fun and great stuff. Works very fast. Data/images are loaded from the web as you zoom in. When you quit the program the stored images are not cached anymore - only while the program runs: ie. when you return to a spot the data is loaded from the harddrive.

The harddrive and the CPU and GPU are working really hard but thats the idea; when getting a new fast such one wants to see how far the computer can go and here its pretty fast. The amount of data available in the PRO version is I believe many GB - mentioned on the http://www.earthviewer.com/ website.

So Celestia and Eathviewer in combination should be possible. I can also mention that the polycount drops in Celestia as you zoom away from a planet.

But where would Celestia get the 1m images from?

nur@softorange.com

so make it optional, or even better, store it on the net somewhere. besides, temporary maps can sufice until the user stops moving (or just put a 3x3 set of tiles into memory, and add/sub when the user moves... and texturing isn't that much of a hit, otherwise we'd be playing flatshaded first person shooters.

I really don't know what current graphics chips are capable of, however JPEG and JPEG2000 have several features which may be helpful. For example with JPEG2000 we could just load the texture at a certain resolution. If we wanted to zoom in, then all that we have to load into the graphics memory is the high frequency content of the image. Also we can choose to zoom into just certain regions of the texture and leave other unused portions at a lower resolution.

yanka