1 Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Qua Jan 26, 2011 1:52 am
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by Gregory Duquesne | |
Landscape Modeling Modeling a landscape can be done in many different ways. In this tutorial we will explore 2 ways to do it: one using the SDTS loader, the other by using procedural textures. Both techniques rely on the use of subdivision surfaces. To create the base object that will be turned into the landscape:
SDTS maps: SDTS images are satellite measurements of elevation maps, they give exact data about the topology of wide areas that cover most of the US map, they can be freely downloaded and are available online. [Tens de ter uma conta e sessão iniciada para poderes visualizar este link] or [Tens de ter uma conta e sessão iniciada para poderes visualizar este link] The SDTS loader was created as an image loader plugin by Marvin Landis. It loads the elevations for each point and converts them to floating point values between 0 and 1. You can then use the image map as a displacement texture to affect the geometry:
<table align="center" border="0" cellpadding="0" cellspacing="0" width="160"> <tr> <td></td> </tr> </table> To set the lighting you can use the LW_SunSpot plugin that will give you the correct lighting conditions given the location and the date and time:
Procedural maps: Another easy way to create a landscape is to use a procedural texture instead of an image map as a displacement. The benefit of doing so is that you can explore the procedural texture, tweak the settings and find the place you like most, which you can not really do with an image map. One the interesting things about procedural textures is that they are often based on fractal techniques, which were themselves inspired by the observation of mountains and coastlines, so fractal textures are naturally well suited for landscape modeling.
<table align="center" border="0" cellpadding="0" cellspacing="0" width="160"> <tr> <td>Landscape Surface Settings For the surface settings, load the scene Snowy_Mountain.lws. From the Render Options panel, set "Enable VIPER" on and render. This will allow us to work on the surface with a direct preview on the rendered image: <table align="center" border="0" cellpadding="0" cellspacing="0" width="160"> <tr> <td></td> </tr> </table> Open the surface editor, open VIPER (in the options or F7), click on "Render" in the VIPER window, you should now see the mountain. Note that the preview does not look exactly like the final render, this is because we are previewing the surfaces, the effects of shadows, fog, pixel filters, etc. are not taken into account for surface previews. We are going to recreate a snowy rocks shader similar to the one used in the introduction image, for that we will need to create a color texture and a bump texture. The bump is used as an additional layer of geometry: it is adding the small details that the displacement can not create considering the limits imposed by the number of polygons that can be used for the model. It is interesting to see how we can model different levels of details with the same tools: the shape of the mountain, the rocks on the mountain, the distribution of mountains in the scenery, everything obeys the same fractal behavior The Bump Texture: Let's start with the bump channel. On a snowy mountain, the bump will vary greatly depending on the presence of snow: where the snow sticks (that is where it's not too steep), the rocks are not apparent and therefore the bump (or roughness) is null. Of course where we have rocks it is very steep and the bump/roughness is high. So we have a simple parameter we can use: we can filter the bump by the slope, that will keep the flat areas smooth and flat and make the steep areas rough and bumpy.
<table align="center" border="0" cellpadding="10" cellspacing="0" width="160"> <tr align="center"> <td> </td> </tr> <tr align="center"> <td></td> </tr> </table> As you can see in the preview, that makes the bump apparent on non flat areas only, we can adjust this by just moving the keys in the gradient. The gradient really acts like a mask on the underlying texture. Now that we have the bump, we just need to set the color. In the surface editor, set the bump amplitude to 0 % for the moment, so that we can work on the color alone. The Color Texture: What we want to do here is to create is a strata rock texture.
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<table align="center" border="0" cellpadding="0" cellspacing="0" width="160"> <tr> <td></td> </tr> </table> Voila c'est fini ! Make a full render (F9), the final image now also has the effect of fog using both LightWave®'s standard fog and the ground fog (Effects->Volumetrics).</td></tr></table> |