Celestia Forums

Hello all.

Over the years I have been a part of the Celestia community I have been asked a few times to create a tutorial here and there to aid other texture creators and there works. Over the last 2 years I have been so wrapped up in trying to keep a friends business afloat that I had basically become an on and off again member. Letting promised projects slip through my fingers and getting nothing finished. I worked as a computer repair technician, and dealing with computers all day long and solving other peoples problems simply put me off from even turning my own computer on except to do some quick web browsing. Well I have separated myself from that problem. I simply couldn't keep doing all the work at the shop and trying to keep things afloat for my friend any longer. I won't go into all the gory details. But I thought I would explain a little about why I have been gone so much.

So what exactly am I going to be doing in these tutorials. Well I will not be going into the basics of texture creation. That has been done by many other texture artist out there. I am going to be delving into more detailed tweaking and tailoring of textures to make them look more realistic. Or in some cases how to make the long promised tutorial on creating snow/ice maps for textures. Another will deal with how I made the terraformed Mars texture and how those techniques can be applied to other textures. You could even use these tricks to re-terraform the Earth per say.

Now I don't have the first tutorial ready yet. But it will be about altering a present texture and making it much more realistic.

For example, I will be taking this fairly old Earth texture that has been around almost forever.



Using Adobe Photoshop, I will show how it can be transformed from a very inaccurate portrayal of Earth into this much more realistic one.



And yes this is the very same 1k texture with just 15 minutes of color adjusting and layering.

I will be using allot of layering in these tutorials. But I will keep the ins and outs as simple as possible so that even a beginner should be able to what I did above without much trail or effort.

I am not sure how i will be making these tutorials. Whether I will be doing them all in one long JPG image as seems to be used on sites like Solar Voyager and Deviant Art, or a combination of separate images with text underneath. It will be one or the other I am sure.
I am not sure if the tutorials will all be posted here in this thread or in a separate thread for each one. With different tutorials and questions all being mixed about in here it could get messy fast. So depending on what I hear about my plans I will decide which way I go.

Well thanks for your time and any other ideas and thoughts are welcome.

So that wraps things up for now.

Don. Edwards

From my experience, step by step tutorials are the one easier to understand whatever level the reader have. The problem is that they can be very long because EACH action done should be one step... The cool point of such tut is that if it is well done you should not have any feedback about problems during the sequence (good if you don't want to loose too much time in answering *in general* pointless questions). So it can be longer to build but will save you some time in after sales service!

Please make them as a combination of separate images with text underneath.

Don. Edwards wrote:Using Adobe Photoshop, I will show how it can be transformed from a very inaccurate portrayal of Earth into this much more realistic one.
Don. Edwards

Many thanks for starting this tutorial, particularly seeing as how you are pressed for time (I know the feeling well...).

Can I ask a question about brightness? The maps on the 'Blue Marble' website are as dark as your realistic one, so your no doubt right. But I would like to understand why. How do we we actually know which brightness and colour to use? I guess you can measure things such as the true colour of the ocean or a boreal forest, their albedo and the strength of light falling on them, but is that enough to predict the actual image? The human visual system adapts to a wide luminosity range; if we were in space, wouldn't our eyes adapt to the view, resulting in more apparent brightness?

Coen,

The rule of thumb I use is if it looks like pictures of the real thing than you have got it. Yes in orbit your eyes would adjust for any change in brightness. But Celestia is not a real environment. Its a 3D working with layers trying give you a sense of depth and space, all the while projecting it on a 2D screen. So your eyes can't work they would in orbit.
My texture coloring choices are made by thinking of what the Earth would like if it were stripped of all atmosphere and seen naked so to speak. If you do this in such a way as I have when the atmospheric elements of Celestia are applied you get a more realistic view of the Earth or any other world. As I have mentioned before our main source of Earth textures is BlueMarble, and they have chosen to give the Earth a far to saturated look to please the average person. As I mentioned to another texture creator in another thread. Go out and have a good look around at the color of vegetation around your area. If you are near hills or mountains look at them. Surprise those hills covered with all those trees don't look green and verdant, but such a dark green as to almost be black. I live in one of the greenest states in the US. I am surounded by hills and mountains that are just covered with forests of fir, maples, and oaks, and countless othe trees and plants. But none of it looks green from a distance. None of it is green until you get up very close to it. The same applies if you were in orbit. All the forest look very dark because they are absorbing more light, while dry grasslands and desert are light because they are reflecting more light back to anyone's eye, even a camera's eye. I could go into even more technical reasons why a dark texture is more accurate.

As for oceans that's simple. It deals with the depth of the water and how clear it is. Water in clear lakes and around shallow seas, look straight to the Bermuda islands for and example, are bright turquoise in color because they are shallow. The great expanses of ocean are so deep that no light illuminates them beyond 50 feet or so. So yes the water is fairly clear over the oceans and it has a blue/green tint but beneath that there isn't any sandy bottom to reflect back the light, just thousands of feet of blackness. Hence the oceans appear almost black in my textures. Except for areas were there are some algal blooms along the coasts near the mouths of rivers, in the colder polar seas, and in some of the open oceans.

Now if we were to find a planet like earth, and it had green vegetation like Earth, and bodies of water like the Earth. Than from orbit it would look allot like Earth. The same laws that govern what we see in an Earth orbit will apply there as well.

I think I have covered all the bases here.

Don. Edwards

One reason forests look dark is that you're seeing under the leaves into their shadows. Shadows are dark

Well that only answers part of that selden. If you are up in a plane and look down those same forests look very dark indeed. Or if you are standing on another hill or mountain looking at a lower peek, again they are very dark. Just because of there nature plants absorb light.

Don. Edwards

Unless the viewpoint is directly between the sun and the direction you're looking, you're still seeing into shadows. I'm not saying that's the only cause of darkening, but it is a major contributor.

And when the viewpoint is directly between the sun and the direction you're looking, you'll see another effect, known as "the glory". It's most noticeable against clouds.

http://apod.nasa.gov/apod/ap040806.html