PAGE 3

SETTING THE SCENE

MORE ABOUT SURFACE MAPS

For the next stage of the tutorial I wanted to create a scene which showed a bay, with mountains ahead and round to the right, some foreground showing, and open sea to the left. I generated several terrains before getting the one below left, which seemed to have the sort of terrain I wanted in the bottom right corner. If I placed the camera position right in the corner, with the target position towards the centre, that would place all the elements where I wanted them.

terrain     render1

However, when I rendered the scene, above right, it was not quite what I wanted. The mountains ahead were too far away, there was too much foreground, and it came round to a point at the left which made the water area look like a lake, rather than the open sea. So I used the sculpting tools (below) to change the terrain to give me what I wanted.

sculpting tools

The sculpting tools are the three green buttons on the Landscape panel. The first button, on the left of the row and shown depressed here, is the one which allows the sight line to be displayed and/or changed, using the left and right mouse buttons to place the camera and target positions. You can also make changes to the sight line by clicking in the same way on the smaller copy of the terrain on the Rendering Control panel, though I find precise changes more difficult on the smaller terrain.

Selecting one of the green buttons opens the sculpting mode, in which you can draw directly on the terrain. The left is the largest one, affecting quite large areas of the terrain, the centre the medium one, and the right the smallest one, useful for spot changes in small areas. Left clicking will raise the height of the landscape at the position under the tool. Click and drag to 'paint' higher landscapes over wider areas. Similarly, right click and right click and drag will lower the height. You can, in fact, use these tools to paint your own terrain, without using the terrain generator at all. In this section, however, I am using them to modify the terrain generated by the program.

Changing the height in one area can give the illusion of changing the height over the whole terrain. For instance, if you right click in the water area, the land will be redrawn and may appear as though its height has been raised. This is because you have lowered the lowest point in the terrain. The actual height of the mountains and land has not changed, but its relationship to the lowest point has - it is higher above the new lowest point than it was above the old, and so the range of colours used in the terrain is adjusted. It will make no difference to the appearance of the land, or the height of the mountains, so do not think if you change one point and the whole terrain seems to change that you have ruined your whole terrain - you have altered the height and appearance only in the place where you used the sculpting tool, but the relationship between that spot's height and the rest of the terrain has changed, and the redrawn terrain reflects that.

Nevertheless, it is wise to save terrains regularly when you are using the sculpting tools. There is no undo in Terragen, and if you make a mistake at any stage you need to be able to recall the previous version.

As you move your cursor around the terrain, the co-ordinates of its position, just like those on the Rendering Control for camera position and target position, are displayed at the bottom of the Landscape panel. The z parameter is the height, and it can be useful for checking how much you have raised or lowered a point. If you wanted water in an area, and none is showing, the z parameter will tell you how much that area is above the height at which water is visible, and you can decide whether to lower it or raise the water level on the Water Control panel.

The changes I made to the terrain were to open up the sea area at the bottom more, bring the mountains closer around the sea ahead of the target position and fill in the tongue of sea going off towards the top right, raise the height of the mountains coming round to the left, and slightly reduce the tiny piece of land just in front of the camera position. I also moved the sun position round so that it was coming in from the sea and lighting most of the mountains, and giving us good reflections of the mountains in the sea. Below is the new terrain, and the rendering.

terrain2     render2

Try to generate a terrain yourself that will give this sort of scene. It does not have to be in the bottom right corner of the terrain like mine. If you find a terrain with water against one of the edges and mountains around the three sides, or enough room for you to paint mountains in, then use that and use the sculpting tools to edit it till you have a bay with mountains around it and sea on the left. It will not be exactly like mine, but a similar one will do very well, so long as you like what you see when you render.

Now that we have the terrain giving the scene we want, we can begin to build surfaces that will give it its character. First, I decided to make grass the basic surface material. With a mountainous scene like this rock will be mixed with grass, and it is a matter of choice which you want to be the predominant material. I preferred to use grass as the base material, which is present everywhere, and add rock later, controlling where it is to appear and in what proportion.

Edit the surface map, (double click on Surface Map in the surfaces list, or select it and click EDIT) select the colour option that we examined in the previous page, and click the green button to make the basic surface material grass. This time also change the name of the surface map to grass, by typing in the new name at the top of the surface edit box, in place of Surface Map.

child layersWe do not want to exchange monochrome rock for monochrome grass, however, so add two child layers. To add a child layer, on the Landscape panel, select the Grass layer in the surfaces list (at this stage it is the only layer) and click the Add Child button. Make sure that Grass is still the selected layer, and click the Add Child button again. Your list should now look like the one on the right.

Click on the top [New Surface] to select it, and click the EDIT button. First rename the surface Dark Green. I left Bumpiness and Mimic Terrain at their default settings and did not use the Reset Bumps button. Click the colour button, and on the colour changing panel, type in these values, then click OK. Red 4, Green 13, Blue 1. The colour of the sample circle has now changed to a dark green.

Now click the Advanced Distribution tab. The illustration below shows how I set it up for this dark green layer, but I will go through each control, explaining what it does, except for Depth which was covered on page 3. Play with the controls to experiment with their effects, but then return them to these settings.

advanced distribution

The small black and white terrain-like image shows the proportion of the child layer which will show in white, and the proportion of the parent layer (our ordinary coloured grass) in black. These proportions are mostly governed by the Coverage and Fractal Noise sliders, but the two constraint settings also have an effect on them, so I leave setting Coverage and Fractal Noise till the others are done.

Altitude constraint allows you to specify that this layer colour may not appear above or below a certain height in the terrain. The little 'snow covered wire' indicator shows the proportion. Where there is bare wire, this layer will not operate. I do not want dark green at the top of the mountains, where the sunlight would make the grass look lighter, so I have set no minimum constraint, but entered 10 as the maximum. This means dark green will not show more than about half way between 'sea level' and the mountain tops. I want the dark green areas to be fairly well defined but not too much so, so I have set the sharp/fuzzy setting to the sharp side of centre.

Slope constraint lets you specify the sort of slope angles where you permit this layer to operate. I do not want dark green grass on vertical or very steep slopes, where it would never appear anyway, so I have again set a maximum. There is no minimum constraint because I am happy to have dark green on flat or gently sloping land. On this slider there are no figures to enter, you move the slider to cover or uncover the slope angle you wish to specify. The same considerations as for the height applied to the sharp/fuzzy setting.

I made no changes to depth, but then set the Coverage slider to make the dark green appear over something between a third and a half of the total area, with basic grass covering the rest. Fractal Noise affects the definition of the layer colour. Taken to the left, the layer colour areas become bigger with little of the base colour in the patches of layer colour. Taken to the right, the layer colour areas are very precisely defined, with no shades between the two colours. Halfway seemed a good compromise.

After setting this layer, return to the layers list on the Landscape control. You still have one layer called [New Surface] so select that, click the EDIT button and rename it Light green. Click the colour button, enter Red 41, Green 60, Blue 29, and OK the box. Then set the Advanced Distribution settings as shown below.

light green distribution

This time I do not want the light grass on the flat, low lying land, so I have used minimum constraint settings. And because there is more lower lying land than higher, that reduced the proportion of light grass and I had to raise Coverage and Fractal Noise to compensate.

grass sceneIf we now render this scene, we have reasonably convincing grass, with interesting changes of colour. It could be very useful to have this ready-made grass to import into future surface maps, so we will save the layer. Click on Grass in the surfaces list in the Landscape Panel, and click Edit. The Save Layer button is right at the top of the panel. Click on that, give the filename 'grass' and save the layer. The two child layers will be saved with it, and any time you want it you can use open it as either a base surface, or as a child layer.

You will notice if you compare this grass setting with the one in the zip file downloaded from Page 1, that they are different. Open the other one as the base layer (Use the OPEN button on the Surface Map area of the Landscape Control) and render the picture. See which one you like best. Make your own if you would like something slightly different. But eventually open your chosen grass layer as the base layer in this scene.

layersAlthough the grass looks good, mountains do not look like that - unrelieved grass top to bottom. We need to add some rock. In the list of surfaces on the Landscape panel, select the grass layer and click Add Child. [New Surface] will appear below light green. Select [New Surface] and click Add Child again. [New Surface] will remain selected and a '+' sign will appear to the left of it. Click Add Child again, then click on the '+' sign. The family tree will open up to look like this. Name these three new surfaces, in order from the top, and use the colours and settings given below. You will now understand the principles behind the settings, but bear in mind that the proportions shown in the parent rock setting relate to its distribution with the basic grass, because it is a child of the base layer. The whole rock layer, including its two children, will share distribution with the two grass colours. But the two child rock layers' distribution relate only to the parent rock. The dark colour in the child rock distribution images relates to the parent rock layer, not to the grass.

Parent Layer: rock. Red 64. Green 64. Blue 56. This parent rock may appear at any height or slope, and will share between a third and a half with the basic grass.

parent rock

Child Layer: dark rock Red 15. Green 16. Blue 16. Dark rock may not appear at lower altitudes and shallow slopes. Notice that the minimum altitude is 0, but our 'sea level' is -10, so there are some fairly low lying areas where it may appear if the slope is steep enough, but the overall distribution of this colour is not great.

dark rock

Child Layer: light rock. Red 80. Green 78. Blue 77. This may not appear at the highest altitudes and steep slopes. Those will be shared between basic rock and the darker colour.

light rock

Now save rock as a separate layer. Select the parent rock layer and click EDIT. Use Save Layer and save it as rock. If at any time you want to load this as the base layer of a surface, you load it using Open on the Surface Map area of the Landscape panel. If you already have a base layer, and want this to be a child surface, you select the base layer and click Add Child. Select the New Surface added by this and click EDIT. On the Edit Panel, use Open Layer to add the rock (or any other surface you want to use) and it will replace New Surface in the layers list, bringing its child layers with it. When you save a World file, or save from the Save button on the Surface Map area of the Landscape panel, the whole surface map, with all the layers, is saved. You can only save individual layers by selecting them and using the EDIT button. Even individual child layers can be saved by themselves, if you select and then EDIT them, and save from the Edit panel. By saving the individual layers, you are starting to build up a library of surfaces that you can combine to make new ones - if you make a sand surface map for instance, you straightaway have the ability to make sand and grass, sand and rock, or sand, rock and grass.

rocks and grassWe now have some rocky areas on our mountains, and they look more real. But they would look even better with a little snow on the highest mountains. The snow layers will be added just like the rock, the main one as a child of grass, and the two for bluish shades as children of the parent snow layer. The parent layer will be constrained to appear only at the tops of mountains, and not on very steep or vertical slopes, where snow does not cling. The two child layers, light blue and dark blue, will have no altitude or slope costraints because they cannot go where the parent layer does not go. They are there to give the snow some depth of natural looking bluish colour. And if I decide later that I want this to be a snow scene, with thick snow everywhere except on vertical slopes, all I have to do is remove the height constraint, increase the coverage to maximum, and we shall have a winter scene.

Snow parent layer: all colours set at 256 (press the white button on the edit colour panel will get this setting)

snow

Snow light blue layer: Red 222. Green 234. Blue 256. Snow dark blue layer: Red 203. Green 220. Blue 236. Both child layers have these distribution settings.

snow child layers

The final settings on the Surface Map area of the Landscape Panel are the two MOVE buttons. If you select a surface these arrow buttons will move it up and down within its level of the hierarchy. You cannot use them to make the snow light blue a child of rock instead of a child of snow. But you can use them to move snow above rock, or bring one of the green layers down to below snow and rock. I have left the green layers where they were and moved snow above rock. The reason is that the last one in the list will be the one to take priority if, say, light green, rock and snow could all be the colour of a particular pixel. If snow is at the bottom of the list, the snow cap looks rather too solid. Move it above rock, and more pixels in the area appear as rock, and the snow cap looks more natural. But if I changed this to a winter scene I would move snow to the bottom of the list again.

When I first rendered the picture, I felt that the reflections were more broken up than I wanted them to be, because the sea was too rough, so I reduced Roughness and Wave Size to 24 on the Water panel. Below is the picture as it stands at the moment. We shall be making a lot of changes to it in later pages, giving it sunsets, night scenes, fog and so on, but we have now a basic scene which can be changed to a winter one with a couple of mouse clicks.

scene

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