Realistic Earth WIP : Need Critique

As you all know there are a ton of realistic earth tuts out here in the web comunity... but none for XSI/Mental Ray... I have a project coming up involving the planets of our solar system that I decided to get a head start on. I figured I should start with earth since it will get the most screen time and be the most nit-picked.

Since the project is somewhat Sci-fi related I thought I'd share it here and get your opinions (and if you have seen this WIP at the various other forums that I put it in, coment where ever you wish).

Basically I am going for a completely in-app earth requiring little in the way of post processing. Since reference on the appearence of the earth differs to such a great degree depending on camera/lens/processing I am doing my own take on what our home planet looks like with the naked eye, and not what popular media has done with it over the years.

Current status of these renders... (C'n'P from another forum's most recent update)

- Adjusted the Color Values of the Surface Map (although I think I went too far with the land color)

- Toned down the light polution coloring of the surface on the "dark side".

- Adjusted the Specular color of the water to compensate for changes to the atmosphere.

- Tweaked the Specular decay on the water surface to tighten it up a bit.

Opinions:

I think I need to toy around with the lens flare brightness on the backlit image, the adjustments to the atmosphere seem to have far reaching implications.

Feel free to comment...

BTW, I'll be making a tutorial on the steps I took with this after the project is complete, so help me make this as good as possible.

[image=http://www.endpointmedia.com/cgtalk/general/earthts5.jpg]

[image=http://www.endpointmedia.com/cgtalk/general/earthts6.jpg]

[image=http://www.endpointmedia.com/cgtalk/general/earthts7.jpg]

[image=http://www.endpointmedia.com/cgtalk/general/earthts8.jpg]

 

Well here is an update.

- Worked on the color maps and added some color variation for the deeper areas of the oceans.

- Did a lot of adjustment on the specular highlights of the water.

- Tweaked the atmosphere a bit more.

- Adjusted the flare effect of the sun.

- Did no post processing on the earth... straight up MR renders on a star matte.

I have worked quite a bit more on the new cloud maps, but they are still a long ways off so the stand-in will remain for now.

[image=http://www.endpointmedia.com/cgtalk/general/earthA01.jpg]

[image=http://www.endpointmedia.com/cgtalk/general/earthA02.jpg]

[image=http://www.endpointmedia.com/cgtalk/general/earthA03.jpg]

[image=http://www.endpointmedia.com/cgtalk/general/earthA04.jpg]

 

Uhhhh....wow. I'll put this in list form.

1. Get bigger maps, especially for the cloud map.

2. What in God's name did you do with the maps to make them appear like that?! I can only guess that you were using crappy ones to begin with. Go here for better ones.

3. Your maps shouldn't be that bright. There's no need to alter the ones you get from the site I just linked to.

4. Something is wrong with your terminator. Having the clouds suddenly appear dark doesn't look good, so you should play with the settings on your lights to avoid that.

5. Make two lights, one for diffuse lighting, and one for specular. The specular one should be tinted yellow, while the diffuse should be white. Keep them in the same position, and tone down the specular one's intensity just a bit.

 

Wow, what a coincidence. I was working on a model of earth for school. I can't show the picture to you now since I'm at school but when I get home I'll put it up. It's better than what you have so far although it's done in Max.

 

LOL... I'll respond in kind...

@diablo

1. I am making my own cloud maps... as the comment says, they are in progress and that is a stand-in that I'm using to get the shaders right. As to the land maps, those are the ones (blue marble) that I'm using.

2. Thanks for the link, I'll check out his cloud maps, but I need a 15min animated one, so I'm making it. Edit: None of the downloads on that page work... oh well, I'll check it again another time.

3. Actually the maps needed and still need a great deal of alteration in most peoples opinion to more realistically approximate the view from orbit... just look at any NASA image and you can clearly see that they are to dark, also there they are not tinted as-is to simulate the light diffusion (can't remember the term, but the blue tint on the land)... there are also no color variations in the sea (except for the reefs) and in many photos you can see slight value variations.

4. I am still toying with that, but it is kind of a dead end atm, until I have time for a ton of trial & error. Since I am doing the atmosphere entirely with volume effect (no faking it w/ incidence and gradients) there is really no treaded path in my arsenal to just "fix-it"... if you have any thoughts on an approach, I'd love to hear it.

5. After a thorough review of hundreds of images, I haven't found one with a yellow cast... I originally (based on the tuts out there) had a yellow spec highlight, but after the uproar about how bad it looked I looked into it thouroghly and don't see any more than a vary faint hint of yellow/green (green from the blue tint). That's what I've simulated here, with some success.

@darth

Okay, yours is better, that's one heckuva critique. Thanks. Can't wait to see it, perhaps you could make a thread on that.

Does anyone have any other comments or critiques?

 

A 15-min animated cloud map? Yikes.

As to everything else, I guess I should direct you here to get some more experienced opinions on your project.

 

Little catchup from other threads...

It seems to be so much a matter of preference... the specular highlight I mean... some people say no highlight, others say yellow highlight, others say white highlight... argh.

Oh well, diversity is good right.


My new current issue is the terminator as diablo pointed out. It's been pointed out that the very sharp change from light to dark clouds is ugly... I agree, but haven't found the best way to compensate for it yet. I am going to toy with the incidence shader driving the self illum intensity because that may be enhancing the terminator's uglyness... I am also going to tweak the negative light creating the linear falloff of the atmosphere... any other thoughts?

Here is a quick image to show how the lighting is setup.

[image=http://www.endpointmedia.com/cgtalk/general/earthA05.jpg]


Also some have mentioned that the specular needs a map, well there is one, and here it is...

[image=http://www.endpointmedia.com/cgtalk/general/earthA06.jpg]

Any thoughts on whether my map needs tweaking, etc...

@diablo

Very cool looking forum... I am already dealing with 3, but I may post there as well, once it gets further along... thanks again.

 

Here is what mine looks like:

[image=http://www.cgfilms.2webh.com/earth.jpg]


Sorry if I sounded kind of mean before because I didn't mean to.

 

I saw your thread in cg talk
nice start
keep it workin

 

Whose thread?

 

LOL... thus why I said to start you own thread here...

No biggie...

Thanks Bertrand, your sausage character is mighty funny... can't wait to see an animation.

 

UPDATE

Well here it is, still a WIP, but certainly starting to look and feel right to my eyes...


- Swapped my lousy cloud stand-in w/ a high res cloud map... (increased render time by about 48%. :-[ }

- Using some basic arithmatic I managed to even out the terminator... it may need a touch more tweaking, but I'd like to hear your thoughts on it.

- A slight bit of turbulence has been added to the atmosphere... it will definitely need more tweaking.

- Adjusted the "dark-side" linear falloff of the atmosphere and I think the tweak really improved the realistic appearence.

- More color adjustment to the color maps.

- More adjustment on the specular...

No post-work other than the star matte.

[image=http://www.endpointmedia.com/cgtalk/general/earthA07.jpg]

[image=http://www.endpointmedia.com/cgtalk/general/earthA08.jpg]

[image=http://www.endpointmedia.com/cgtalk/general/earthA09.jpg]

 

Getting better.

Maybe it's just me, but I still think that the whole thing is overbright. Can I see the reference images you're working from?

The atmospheric glow in the second picture has, when it's falling off along the edge, a sliver of black underneath it. Needs fixing.

The clouds seem a little high up. Try finding a source on average heights for different types of clouds, and then average them to get a value for the radius of your cloud sphere. Then do a bit of number crunching to make sure everything matches. Props if you've already done this.

 

Hey Thanks...

Here are just a handful of the references... as I said in the first post, depending on many factors, the published photos of earth vary greatly... this is along the lines (but not exactly) what I am going for. No doubt I am still a long way off... but considering I expected to work on it for at least another month... I think I am moving along very nicely.

[image=http://antwrp.gsfc.nasa.gov/apod/image/mir_sts63.gif]

[image=http://grin.hq.nasa.gov/IMAGES/SMALL/GPN-2000-001046.jpg]

[image=http://www.btinternet.com/~fireballxl5/space/earth/pics/a12_h_50_7325.gif]

[image=http://earthobservatory.nasa.gov/Newsroom/NewImages/Images/ISS008-E-8951_lrg.jpg]

[image=http://eol.jsc.nasa.gov/sseop/images/EO/highres/STS075/STS075-773-66.JPG]

All of the measurements are entirely basesd off of the published measurements of the subject matter...

Sun Radius = 70 units (700,000km)

Earth Orbit = 14960 units (149,600,000km)

Earth Surface Radius = 0.638 units (6380km)

Average Cloud Radius = 0.640 units (6400km)
* According to the US Naval Research Laboratories - Monterey Marine Meteorology Division the average height of cloud tops is 19.3025km (Max is a crazy high 70km) so I approximated my cloud sphere to be 20km above sea level.

Earth Atmosphere Radius = 0.660 units (6600km)
* The sphere is essentially a bounding container for the volumic effect. The falloff begins at 0.638 units and ends at 0.659 units. In all actuality I should increase it to encompass the 70km cloud heights, but my new cloud maps displacement will only go about 40km, it should look good.

So props for the props my freind. =)

 

I'm not sure about your data. To me, your atmospheric "aura" seems much thicker than it ought to be.

I created this image to help me visualize the appearance of Earth's atmosphere:

[image=http://www.cgideas.btinternet.co.uk/atmosphere.gif]

I don't remember the exact values that I used, but I'm pretty sure that my atmosphere is less than half of the 210 km that you're using.

Each "stripe" represents a 2x magnification of the one below. The red gradient represents the atmosphere, although it doesn't accurately reflect density. The white band represents clouds and the blue band is the ozone layer, which is responsible for most of the "aura". Above the ozone layer, the atmosphere is pretty thin.

In other words, the aura shouldn't extend far beyond the blue band. If you compare the diagram with real pictures, you'll see that this is about right. Remember that "close-ups" (from the Shuttle, for example) can have heavy perspective that can make the aura appear thicker than it ought to.

 

Yeah... I think your on to something.

The measurements I based the atmosphere off of are based upon the true end of the gases... I need to adjust the falloff ramp alot... thin out the upper regions significantly and increase the overall density to compensate for the color change.

Good point... thank you. But I gotta admit (and maybe I am just fried) I can't make heads or tails out of your diagram...

 

try Zorbi's page, in scifi3d link section, he has done excellent earth pic, maybe it can help you

 

Psuedo Update before bed...

- Lowered the radius slightly of the cloud sphere.

- Added a spec map to the clouds... I think it still needs adjustment.

- Lowered the radius of the atmosphere.

- Adjusted the falloff of the atmosphere.

- Increased density and brightness of the atmosphere to compensate for reduction of volume.

- Adjusted linear falloff of atmosphere darkside.

No post processing. Just quick snapshots of the render region.

[image=http://www.endpointmedia.com/cgtalk/general/earthA10.jpg]

[image=http://www.endpointmedia.com/cgtalk/general/earthA11.jpg]

Night folks... looking forward to comments (focus on atmosphere & specularity appreciated).

PS - Hey Dr. J, yeah zorbi's are beautiful... too dark imho, but beautiful none the less... love his water effect. I may toy around a bit with the "glistening" and reflection he is using... but it will only be visible in the closeups, so I will see what I can do in some tests. Night.

 

i'd just like to say WOW!

 

I know a site where you can download some textures
here
...if you want..

 

BY POPULAR DEMAND

I have been approached repeatedly about advice on how to do an earth in XSI... I do intend to create a thorough tutorial in the future that goes over the concepts and techniques in detail, but to wet tastebuds and perhaps stem the flow of requests for individual guidence, I will now post a very breif set of instructions on the very basics of recreating what I have done here... I will however not be giving instructions right now on how to recreate my atmosphere.

To see this tut-let go here http://www.cgtalk.com/showthread.php?s=&postid=1266632#post1266632.

For all the folks who will come in and comment on these most basic guidelines saying you shouldn't do "that" you should do "this", make your own thread or tutorial. Hope this helps guide some of you folks in a good direction, at least until I publish the actual tutorial.

Cheers and Happy Easter/Wookie Fertility Holiday


PS... Please do not post any questions about this little tut-let here or further instructions... I would really like to keep this thread on topic and target.

Thank You.

 

What really bother me is this specular, really looks like a pool ball. I think a good water effect should have a smaller glossiness level (I talk with max settings, don't know how is called glossiness in XSI), with a mask, for water only.

 

looking good

 

If you're aiming for REALISTIC.. then there's one major thing no one seems to have noticed... whenever you see a planet or a moon... when you see the bright side... you can't see the stars... so remove all the stars in pictures where you have a brightsided planet/moon...