Celestia Forums

Well I have been keeping an eye on the Space-Graphics site and they have released a new Mars texture that has NO SHADOWS what so ever. So I downloaded it to give it a test. After getting it resized from 5700 to 4096 and saving it as a png versus .jpg I did a little contrast adjustment. The final product looks OK except for one thing. Apparently the new bumpmap that goes along with the texture are out of alignment. Have a look. This is over Noctis Labyrinthus.

I going to email them and let them know about this. Hopefully they can fix it. The texture has some promise if they can fix the mismatch.
Here are two more shots of their new Mars texture.



Don "Martian" Edwards.

Hi Don,

I've checked the new Mars textures at Space Graphics (an umbumped Mars, at last! I love to see that dinamical bumpmapping effect ) and checked both main texture and elevation map, but I find strange that I'm not having any kind of problems with the bump effect as yours

Here are some screenshots:




P.S. I haven't done any modification to the textures only corrected the prime meridian on both maps and converted them to dds format.

Don't forget that Celestia v1.3.0final has problems with bumpmaps. You need to do the comparisons using one of the pre-releases or with v1.2.5.

Oops! I forgot to mention, using Celestia 1.3.0 Final

praesepe,
You did resize the texture didn't you? That all I did to the bumpmap and the texture. The little color changing I did count account for the sift.
I am using it on an olde install of Celestia. I am going to convert it all to .dds and try again just for the heck of it.

Here are a couple shots with the new Space Graphics textures and fixed bump mapping:




I resized the textures to 4k x 2k and converted the color map to a DXT1 .dds file. I also toned down the bump height a bit, for a more subtle relief effect. The only artifact that I notice are some diagonal streaks on the Olympus Mons image . . . I'm not sure what's happening there, but it appears to be an issue with the bump map. Overall though, if these images aren't enough to make you go out and buy a new graphics card with a ton of memory, I don't know what is

--Chris

Well after doing a great deal of tweaking I got everything to work. But, after all is said and done the texture just leaves me feeling flat. Ha-ha!
There is just not enough detail at this resolution to sell me. Maybe if they can get the 10k texture up so I can work with that at the 8k level I may give this more thought. What my own private goal is to be able to recreate one of my favorite pictures of Mars from NASA. Take a look at this.


Now this is a screen cap of the new texture tweaked a little trying to emulate this picture.


And now this is the texture I have made for the project I have been working on.


Sure the old texture has shadows but it helps give some extra detail to the image. The problem with the Space-Graphics texture is it’s just too flat. Sure they got rid of the shadows but in the process they killed all the detail. The only way to get it back is to crank the settings on the bumpmap way up. But then again this still doesn't give you the detail that is lost. And the more I look at the texture the more its stating to look like it is just a colorized version of the bumpmap anyway. I am planning on trying 2 more things to see if I can get this thing to look better before I move on to other things. I will post my results here as soon as I am done.

Don “Martian” Edwards.

I just downloaded the mars,no shadow texture,
after 5 min looking at it I am DELETING it
VERY BAD .jpg texture
--NOT YOU -- Space Graphics
Just look at all this .jpg GUNK

This was from the med res 5k zip file from Space Graphics



This one is my 8k mars tex that i am using
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Ok, Now were talking. I have got some detail back in the texture. Give it a compare to the previous posted images.


And a closer view.


I ended up haveing a flat topped Olympus Mons so I have to rework the bumpmap. But you can see there is more detail in the texture. This texture still has miles to go. I only hope Space-Graphics releases at least a 10k so we can convert it to 8k and that should help regain some of the losses.
Don.

I notice in comparing the top two pictures in Don's last post that the three Tharsis volcanoes (along the limb in the upper left quadrant) appear as dark spots in the NASA photo but bright ones in the texture. This seems strange.

- Hank

Hey John,
Did you convert it to a .png before resizing it? That helps keep some of that garbage from showing up. But I must agree with you. Unless they release a 10k that can be reworked this texture is a bust. I can't believe all the hoops I had to go through just to get the detail up. I won't bore you with the details. It did work but in the end all this for a 4k texture is just a bit much. As you can see from my posts it got better but I think I will stick to the textures I have.

Hank,
I think part of the reason that they apear dark in that photo is there is a duststorm all over tharsis in this photo. The volcanos are tall enough to poke up through the dust so there is an increase in contrast. But I have always felt all the Mars textures show the volcanos a little to bright in color. In most real close ups of them they apear quite dark.

Don "Martian" Edwards.

the first thing i did after unzipping it was to use gimp to convert it to png
All my textures are png except for --gstar .jpg ,astar.jpg ...

Well, after playing a bit with the new flat Mars textures I tried this little experiment. As Don says, the guys at Space Graphics have removed lot of detail on the new textures, so I've merged the data from the old Red Mars textures with the new ones. These are the results, a nearly umbumped 8K Mars, but much more detail.

Take a look at these pics, they're with and without bumpmapping enabled:

Indeed, the new 5k un-shaded SG2 mars texture is no good. I have tried to play out all the tricks I know to improve the display. Hopeless. The best display I get is by scaling the texture up to 8k (in order not to vast any pixel info) and of course converting the jpg to some lossless format, before doing any further manipulations with it. The color rendition is /very/bad with lots of artefacts despite my consistent 24 bit treatment throughout. 8bit bump maps are also by far inadequate. Imagine characterizing the huge altitude difference between the top of mons Olympus and the bottom of the huge valles Marineres canyon by merely 256 steps!

My latest mars textures (to be found in the TextureFoundry soon,) are /way/ better!

Bye Fridger

Just to add a little pence to the discussion, I have prepared a page that shows some kind of comparison on the matter.
You'll find it at:

http://www.ara-frasso-sabino.org/andrea ... ia_bis.htm

By

Andrea

Fridger,
What I did with mine was to attack the bumpmap. I adjusted the contrast and brightness just a liitle. Than I used an unsharp mask the clean things up. This brought out some hidden detail. I then added it to a slightly color corrected version of the shadowless Mars texture. I then reduced its opacity by 85%. This also aided in adjusting the color some but most important it brought out more detail. Not a allot mind you but just a touch. I am still of a mind to write these guys over at Space-Graphics and let than have my opinion of the texture as a whole. I still think all they did was colorize the bumpmap.

Hi all,

Here is my version of a new 'bumpless' Mars. The shot are made with 'Basic rendering' and 'None ambient light'.





I merged my old 'bumpless' 8k Mars map with the new flat Mars map from Space-Graphics. Now you can see that this 8k map is not complete bumpless but it's good enougth to work fine with a 8k normal map.

I've uploaded a JPG version of this texture on my home page. John, I've checked carefully that I have not added artifacts ;-).

Attention, my homepage has moved. http://home.arcor.de/jimpage/

Don, i think your Nasa picture isn't a photo but a color enhanced render image. I have this and other mars globe pictures on my disk. I would not use this pictures as reference.
Selden has posted some good link about the real colors in our Solar System.
http://www.donaldedavis.com/2002_addons/SSYCOLRS.html
http://www.donaldedavis.com/PARTS/MARSCLRS.html

Maybe that my texture is a bit to bright. Further must be add a 'shining orange' by the clouds and the haze effect to get a more realistic view from the orbit.

Bye Jens

My initial excitement about the space graphics textures has waned as well . . . I'd been focusing on the areas near the terminator, where the bump mapping reveals an adequate amount of detail. In other places, however, the texture is indeed much to flat and devoid of detail . . . I think that a part of the problem is that standard bump mapping doesn't show cast shadows--the lighting variations are all due to the varying angle between light and surface. Actual images from spacecraft will show additional detail from cast shadows. That's not the whole problem though--it appears that real albedo variations of the surface were lost in the production of this texture, too.

As t00fri noted, the 8-bit height map is a big problem too . . . Using 16-bit height maps as a starting point gives much better results, even when the result is an 8-bit per component normal map.

Here's my analysis . . . Mars has a radius of 6794km, giving a circumference of roughly 20,000km. With a 4k x 2k texture, each texel represents 5x5km at the equator. The altitude range on Mars is 31km from the bottom of Hellas Basin to the top of Olympus Mons. The bump height should then be 31km / 5km, or about 6.0. What a bump height of 6 means is that you're throwing out a lot of data--the resolution of the normal map computed from the height map is 6/256. The ideal resolution of an 8-bit normal map is 1/128 (not 1/256, because normal map components are represent values in [-1, 1] not [0, 1] like colors). Very important to note is the fact that with larger bump maps, you need a higher bump height, which further reduces the resolution. 16-bit height data is essential for generating large, high-quality normal maps.

Once I get a GeForce FX at home, I hope to find time for some experiments with 16-bit per component normal maps to see how they affect rendering quality.

--Chris

Praesepe,
Any chance of you uploading your textures to your page? I'd like to try them out on my machine, as I have no clue how to make my own.

Thanks,
AC

While it's true that bump mapping doesn't give you cast shadows, I'm not sure that's the main problem for planetary surfaces, where the relief is small compared to the planet's radius. Shadows can't get too long before they hit the terminator. Sure, it would be nice to have them, but they're just not feasible with current graphics technology. Maybe when we have real-time ray casting... But shaded relief maps don't show cast shadows either, and they seem to give a reasonable appearance. Maybe some kind of relief exaggeration to enhance contrast would help. Chris's comments about normal map resolution sound plausible. I also wonder about the effects of applying compression to normal maps. Compression techniques designed for visual images wouldn't necessarily be expected to work well with normal maps.

- Hank