Manipuler les surfaces dans Terragen


Manipulate surfaces withTerragen

Introduction

Terragen is a wonderful netscape rendering tool. Atmosphere and lighting effects remain it's strong points with their few parameters (compared to other products) which almost all have a "physical" existence.

Between the "I click, and we'll see..." approach, which has it's charm, and is far from being innefficient, and the "let's see what this thing means" approach, the second one is certainely more interessant as it will allow to advance towards realisations.

I here propose you a brief summup about terrains textures conception. The fact of elaborating them appart from the other parameters allows you, during the restitution, to only play on Terragen's surrounding elements : mist, clouds, light, etc...

A nice texture is also a key to succeeding in making a good animation.

Here are the steps I propose :

0- take some height: how to use a sattelite view to create the surface.
1- chose the surface map : surface +++arborescence.
2- plants / minerals distribution : distribution considering the slope, use of répartition depending on the slopeness of the hill, use of the bias.
3- trees / dry grass distribution : dsitribution depending on height.
4- pine trees / oaks distribution: random distribution.
5- rock / sand distribution : idem for rocks and sand.
6- colors : choice in the layers'colors.
7- final calculations

Take some courage, and let's go!


	WARNING : this guide was made seperatly from Matt Fairclough's Terragen project. Ti was conceived once I had Terragen, but it may have some mistakes...which will not engage anybody's responsability. Any comment good or bad will be welcome, in order to know if it was useful to someone. If you wish to put these pages on line on your site, it's possible if : 1-you don't modify them (text, image) and 2- say it. Any commercial use requires a prior agreement.


Manipulate surfaces withTerragen

0- take some height

Open the demosurface.terrain file from the Landscape window. We're going to see what it looks like, and to do that, nothing's better than a sattelite view.


In the Rendering Control window, place the camera in the center (x=y=128) and very high (z=800). Place the target right under it (x=y=128,z=0). Preview the result: the terrain is far, and blueish : mist hides details of it, and a good zoom wouldn't be bad. Zooming : in the Rendering Control/Camera Settings window, setthe zoom to about 5.6. Suppressing atmosphere : in Atmosphere, set simple haze, atmospheric blue and Light decay / Red to 0%. You have now got a sattelite full of filters to attenuate atmosphere effects (which is rather sad when you have Terragen!) and you can take a first picture with high details (fig 1). A landscape with high hills, a Noth/South Valley ended by a cirque and a col, all of it is hailed. We are now going to look after conception of the different textures, that we'll be able to observe with our satellite. Let's try to make a Pyreneen landscape (dark and bright rocks, little sand, dry grass up high, pine trees and oaks in low spots. We are getting into the subject now. Please note that I don't often go in the Pyrenees, sorry if all it's got of Pyrenees is the name...	*fig 1 :* satellite view!


Manipulate surfaces with Terragen

1- chose the surface map

Even if Terragen allows you, by a few random clicks, to get a beautiful realistic landscape, you will have to note down a few things if you want to get a specific result, for example a Pyrenees texture.

Terragen uses altitude and slopes to distribute textures. It's very important to keep that in mind, since they are the only two factors on which you can do something.

In our case (as in most cases), slope will be the main caracteristic that will determin rather there should be minerals, or plants. A first minerals / plants distribution is required.

After that, we'll have a different vegetation depending on altitude and maybe slope. In the same way, we'll have sand on not steep hills, and in holes.

Finaly, rocks can have different colors depending on the same factors.

At the end, we should get something like this:

Landcape (distribution depending on the slope)
|--- vegetation (depending on altitude)
|........|--- dry grass
|........|--- trees (depending on slope and l'altitude)
|.................|--- pine trees
|.................|--- oaks
|--- minerals (depending on slope and l'altitude)
|........|--- sand
|........|--- rocks (random distribution)
|........|........|--- bright rocks
|........|........|--- dark rocks


Manipulate surfaces with Terragen

2- vegetation / minerals distribution


It's not necessary to change the colors yet, because the default ones allow us to clearly see the first two textures: minerals and vegetation. To distribute the two textures, double-click on the knot just above them (here, "landscape"). To change a color, change on the texture you want to change (vegetation or bare)	*fig 2 :*selecting
A first calculation without any changes gives this (fig 3) : There's a little to many rocks (personnal opinion :), and if we want to put some dry grass on the summets, they have to be green. By double-clicking on "landscape" you will get to the following window: *fig 5 :* distributions settings Deactivate altitude effectiveness (vegetation and minerals at all heights), set the other parameters to about 50%. Then, we'll look after Overall Surface Distribution to get more vegetation than mineralswe get this (fig 4), In green, we have all vegetations, in grey, we have bare areas.	*fig 3 :* before *fig 4 :* after


Manipulate surfaces withTerragen

3- trees / dry grass distribution

The distribution of different plants is determined by altitude and (a little less) by slope. On the combs, we'll have dry grass, and in valleys, trees.


Create a vegetation : dry grass and trees. you have to change the color of one of the two to see it well. Let's set dry grass to a military green 92/110/20 for example : (fig 6).	*fig 6 :* dry grass colors settings
Then, set the trees / dry grass distribution by using altitude as main distribution determiner(about 80/20). you might have to use the"negative correlation" box to invert trees and grass: the two vegetations will be switched. Small maps represent the distribution in black & white ; in the top of the window, two text lines indicate correspondances. Set other effects to your liking, but they must not hide distribution set by altitude. "surface modifier map" uses altitude data to disperse other distributions effects, to make things look more realistic. The following settings : altitude 80/20, slope 30/70 and surface modifier 30/70 give this (fig 7). 30/70 means 30% is grass (so 70% is trees)on the distribution cursor. For the moment, colors have no importance. They just help to see which is which.	*fig 7 :* dry grass setting


Manipulate surfaces withTerragen

4- pine trees / oaks distribution

Not being a professional in pines and oaks, I don't know how they're distributed. On top of that, to be realistic, one would probably have to look after wind and sun directions... Which Terragen doesn't currently do. I will then propose a random distribution (only to make different colors of trees to make our landscape look better).



Create a distribution in trees : pines et oaks. Starting to get hairy :) Set two different colors to pines and oaks (like green-green, and red-green just for fun). As far as distribution is concerned, the best is not to force the values, so as to have a mixed vegetation. Warning, think of ticking the"negative correlation" box to invert an effect if necessary. Here's what it gives with the following settings (fig 8) : pine trees color: 18/30/9 oaks color: 56/32/12 altitude based on distribution : disabled slope based on distribution : disabled surface modifier : 60/40 bias : 50/50 We can see how the fact of multiplying colors give a much better effect.	*fig 8 :* green and brown trees

We're done with vegetation! All we have left is minerals rocks (dark / bright) and sand.


Manipulate surfaces with Terragen

5- rock / sand distribution

The following instrucions are very much like the ones for vegetation. Now that you're familiar with Distribution Settings, you can follow these instrucions:

divide minerals into rocks and sand ;
give a grey color to rocks and a bright color to sand (35/32/32 and 96/80/64 in the example below) ;
then distribute the two minerals depending on the slope (50%), on altitude (50%). You can if you want, disable the Surface Modifier.
divide rocks into bright rocks and dark rocks (115/109/99 et 35/32/32).
distribute them using only Surface Modifier.

You should get something like this (fig 9 et 10) :


*fig 9 :* adding the sand	*fig 10 :* rocks of two differnet colors

We're done with the hard stuff! All we've got to do now is give colors (nice ones).


Manipulate surfaces with Terragen

6- colors

Setting colors isn't hard: you can make yourself a typical "surface map" that you'll be able to use for all your landscapes. Here's an example :


LAYER	dry grass	oaks	pine trees	sand	bright rocks	dark rocks	*fig 11 :* complete map
parent	vegetation	trees	trees	minerals	rocks	rocks
brother	trees	pine trees	oaks	rocks	dark rocks	bright rocks
distribution	altitude	no	no	slope	no	no
COLOR red green blue	35 46 18	34 21 6	18 30 9	96 80 64	67 69 67	27 24 24

NOTE : If your screen doesn't support 16 Million colors, these colors aren't good, but anyway, you can't use Terragen so...


Manipulate surfaces with Terragen

7- final calculations

Don't forget to reinitialize the zoom, and to set atmospheric parameters that we had suppressed to use satellite view. Place your camera and the target, set the atmosphere (default settings should do), clouds, sun, water if it makes you happy.

When you see your first picture, don't be disapointed not to see all the textures you just made: they'll be easier to see in an animation since the camera will go and see different angles.

image finale
camera : (114, 251, 10) target : (128, 128, -17,4) zoom : 1
atmosphere : default lighting : multidirectionnal
post-processing : spectrum stretching

The two trees textures pine trees and oaks don't really look like tree as they have no thikness. Maybe one day, real trees in Terragen... But untill then, good luck ! Don't hesitate to send me other methods to make textures...