long loading times

[HughKay]

Hi, I'm using Celestia for several months. One problem, however, always occurs: I've downloaded several high-res images for the earth, the moon, mars etc. And every time I try to switch the resolution from medium to high, my computer almost hangs up because loads and loads and loads...
I have to wait almost 5 minutes before the 8k-image is loaded!!!
Once this is done, it loads again when I e.g. try to rotate around the earth. After this 2nd time of loading everything works again without any problem.
Is that normal or did I do sth. wrong???
I have Celestia 1.3.0 pre2.
(OpenGL works, at 1024x768, DXT texture compression installed)
My system:
AthlonXP 2000+
WinXP Professional
Geforce4 Ti 4600 with Detonator 43.45
512MB DDRRAM

[billybob884]

I've noticed this too, loading times seem to get increasing longer with every new version that comes out, even though no new higher resolution textures have been added (for me anyway).

[jim]

Hi HughKay,

Which file types do you use? If they are PNG or JPG then it's normal but if you use dds files then something is really wrong.

Bye Jens

[selden]

Don't forget that as you add and delete more software packages the disk gets more and more fragmented. If the new image files wind up being scattered in pieces all over the disk, loading them can be quite slow. It might help to run a disk defragmenting program.

[billybob884]

i have recently done one of these, no improvement. I'm going to try telling celestia to go to another star system first.

[HughKay]

Yeah, most of the high-res images are .jpg
Therefore,if that`s normal that I have to wait for so long, how can I improve the speed?
Does it depend to the program-source code or are the normal pc-machines we are running this cool program on too slow???
Is it possible to convert a jpg-file to a dds one? Would that help?
Are there any quality-losses if I do so?

[selden]

Well, while playing with my "billboard" I found that 2Kx2K jpeg images were taking longer to load than I was willing to wait, so I don't know how long it would have taken. This system has a 32MB Radeon 7000, so it shouldn't be a problem of them not fitting into its memory, since 2Kx2Kx3=12MB. In contrast, a 2Kx2K DDS DXT1c texture of the same picture loaded immediately -- faster than I could measure. (It did hang when I tried to load a 4Kx4K DDS file, but that's not surprising.)

Hugh,

You'll need to invest the time in learning how to use image manipulation programs. Nvidia provides free DDS conversion utilities and Photoshop plugins at http://developer.nvidia.com/view.asp?IO=ps_texture_compression_plugin although I haven't been able to get nvdxt to work with JPEG files. It works fine with TARGA and TIFF files, though.

[chris]

Well, while playing with my "billboard" I found that 2Kx2K jpeg images were taking longer to load than I was willing to wait, so I don't know how long it would have taken. This system has a 32MB Radeon 7000, so it shouldn't be a problem of them not fitting into its memory, since 2Kx2Kx3=12MB. In contrast, a 2Kx2K DDS DXT1c texture of the same picture loaded immediately -- faster than I could measure. (It did hang when I tried to load a 4Kx4K DDS file, but that's not surprising.)

Actually, the 2Kx2K JPEG takes more memory . . . It's unlikely that the hardware really supports 24-bit textures; it's probably stored internally at 32 bits per pixel, bringing the size up to 16MB. In addition, mip maps increase the size by an extra 1/3 (sum(1/2^2n), n = 1, 2, 3, ... is 1/3) So, you're going to end up with just over 21MB of texture data on the card. A DXT1 version of the same texture would only be about 2.5MB.

--Chris

[Guest]

Chris,

Thanks for the clarification.

It'd be nice if Celestia could generate a flash message when there's no room to load a texture. Presumably there's no standard way to find out how much room is left (I seem to have some vague recollection of you mentioning something like that.) Oh, well.