Celestia Forums

Hi.

How to treat bug of distorsion of image when look at surface under small angle? The effect is very strong on small altitudes (some kilometers) when look far away. I use dds VT with tiles 256 on 512, dxt1c, without mipmap.
I suppose, it may be fixed, if rendered level of VT depend on distance to tile and angle of vision, not only on altitude.

And the 2nd question. How to increase quantity of VT levels from 13 to 18? I tryed to increase instead it basesplit, but Celestia crashes.[/img][/list][/list]

TheOWHSM,

You'll have to provide a URL linking to a picture of the distortion that is bothering you. Without knowing what it is, it's hard to say anything.

Celestia only supports 13 levels of VTs. Sorry. It's limited by the number of vertices in the model of a sphere that Celestia uses. More vertices would cause Celestia to run more slowly.

The only way to get better resolution at the last level is to use larger tiles for it. The tile sizes do not have to match the size specified in the .ctx file.

Here is:



The bug is especially unpleasant, when move. When you look vertically down, the bug absents.

There is triangle piece of surface (on right half of the image) of lower VT level, that looks better.

I think, roots of this problem are same with one, when look at dds texture without mipmap from very far distance, but here picture "compressed" in one dimension only.

Are your tiles really 256x512 as you write above??
Is this just the base texture? Or do you also use a normalmap?? What texture is this?


Where did you get these from? Ever tried square tiles?

Why don't you use my nmtools package and do a excellent normalmap from the original 85k elevation map. What you show above is quite horrible...I never have seen anything like that.

Always quote the Celestia version!

Bye Fridger

Yes, it is 256x512. I use it for economy of disk space (distance from equator of these locations is about 50 degrees). First I used 512x512 tiles, then I read, that dds files may not be square, but its height and width must be power of two, and remade. Nothing changed, except disk space.

What is "base texture"?

Yes, I use normalmap. Also I use all other maps: cloud, night, spec. All VT, levels 0-4.

This texture is, as I already said, VT dds, dxt1c, without mipmap. Tiles of levels 0-7 are 512x512, ones of levels 8-12 are 256x512. BaseSplit 0, TileSize 512.

The pictures are from Google Maps.

I'll glad to use your nmtools package, if it is really useful, and you tell me, where I can download it and 85k elevation map. (But more I'd like to have something like "virtual models", but it is only dreams...)

Celestia version 1.4.1.

I am convinced that you did something wrong.

My normalmap tools and a tutorial are on our CelestialMatters site. Just click on CelestialMatters at the bottom. Many discussions you also find in this forum, but you seem to be pretty new here...

http://www.celestiaproject.net/forum/viewtopic ... 46&start=0

You also seem to have little idea about the use of the appropriate compressed formats. DXT1c is absolutely unsuitable for normalmaps yet OK for the base texture. The base texture (the one carrying the RGB color information) should be "flat" not (statically) shaded, since it will be shaded dynamically by the normalmap.

Go and get Celestia 1.5.0pre2 or compile it from CVS if you have Linux. There is sooo much new that it's not sensible to do all the stuff now for the old 1.4.1 version. You'll find plenty of discussion in the forum about the new normal map stuff. Just look in the Developer Talk, Celestia Development and Celestia Textures boards.

For normalmaps there is now a SPECIAL compressed, yet high quality DXT format, the socalled DXT5NM, with file endings assigned to .dxt5nm. And so on...it's a lot to learn for newcomers. Perhaps it's better to learn first what's new before you do you own custom textures.

Except if you have a really low-end machine, I'd recommend 1024x1024 basic tilesize. The smaller the tiles, the more your drive has to work! Tile optimizations should be done automatically with any good VT generating program. My well-known VT script, 'virtualtex', does not have it yet, but I meanwhile wrote a new script to do the optimal reductions in resolution. This will be published in CelestialMatters as soon as I find a little time. Soon this will all be part of new compiled tools in C++ for the base texture and other RGB maps. The forthcoming tools will be much faster, of course, than the previous shell scripts.

The nmtools exist as binaries for any operating system and of course the sources are also part of the package.

For normalmaps, the nmtools are the first to produce geometrically correct normalmaps, implement ALL OPTIMIZATIONS including the optimal decrease of resolution towards the poles and the reduction of monochomatic tiles to only 4x4 pixel size. The latter two optimizations save lots of hard disk storage without compromizing in quality! Also, the nmtools are VERY fast and meant to really make BIG, highest quality, normalmaps on normal home computers, without requirement of excessive memory and disk space.

ALL previous normalmap code used the gradient calculation algorithms for FLAT surfaces, while in Celestia we need SPHERICAL geometry. That implies BAD errors towards the poles if you do NOT use the nmtools!

Since I have little spare time (that should rather go into Celestia development), you'll have to find the rest out yourself.

Good luck,
Bye Fridger