Thanks go out to Vincent Ferrand for this week’s Vue tutorial. You can see more of his work at cornucopia3d.com
The close-range iceberg has been modelled in Acropora. It’s a procedural voxel-modelling program that’s easy to use and has a lot of potential. It can create organics, terrains, caves, rocks and many other textures. This particular shape was obtained from a single cube, onto which various procedural functions were applied to get the desired effect. In order to get as much detail as possible, the voxel density was increased to 512 x 512 to generate a high-poly object (over 2 million). However, when Vue imports the object, it’s somewhat smoothened and many of the smaller details are lost.
For the long-range ice, I decided to use GeoControl2 as my modelling tool. In this particular case, it gave me better control over what I wanted to achieve. The 16-bit TIFF (4,096 x 4,096) generated from GeoControl2 is then imported into Vue via a procedural terrain. To add some variation to the overall shape of the ice ﬁeld, the picture was blended with a very small amount of the Rocky Mountain algorithm. The terrain was ﬁnally stretched to get the desired aspect ratio.
Next we are going to look at the material of the close-range iceberg in greater depth. First we will adjust the Color map. Instead of using pure white for the material we will be using a slightly turquoise-tinted map. As mentioned before, for some reason Vue smoothened the imported object to the extent that small details are lost. This is why we will add a Bump map to compensate for this undesired side effect. Displacement could also be added but this dramatically increases render times. As you can see in the screenshot the iceberg still isn’t very realistic. This is the stage where Vue’s Translucency feature will bring the berg to life.
The ﬁrst thing I did was to set the Refraction index to 1.309. The Average depth to which the light will penetrate is set to 1m; this might seem a lot, but it’s linked to the object’s size and distance to the camera, in this example. I then enabled the Multiple scattering box. The Balance parameter under Translucency is increased to 75%. Next the Absorption ﬁlter color is set to light blue and this will deﬁne the translucent colour as the light travels through the object. The Multiple color (diff use) is set to a very soft blue to give an overall bluish tint to the iceberg. The last step is to push the Quality boost to at least 3 in order to reduce noise (it does increase the sample taken to calculate the SSS) and get more realistic SSS behaviour. To complete the material, some highlights are also manually added to account for the shininess of the ice in the sunlight.
For far-away ice the use of subsurface scattering is not really a necessity. In my view, it does not bring any real beneﬁt – but it does signiﬁcantly increase render times. Here the material is made of a base blue ice-like material and a top snow layer covering the ice. The ice material uses a pale blue Color map and has a Bump map made up of a combination of different functions. Because the distance between the ice ﬁ eld and the camera is quite sizable, the Depth of the bump is set at 28. In the Effects tab, the Backlight is set to 10% and the Luminous level to 1%; this gives a slight glowing effect. The top layer is a completely white powdery material to simulate freshly fallen snow.
In this scene, I have used the Spectral atmosphere model in combination with GI. In order to replicate what could be an arctic blue environment, a dark blue shade was used for the sky and the Light intensity was increased to +0.25. The Sky dome lighting gain was also pushed to +1.8 to create some appealing indirect lighting on the front of the iceberg and the distant ice ﬁeld.
Vue’s Translucency function does not seem to be used very often, which is a pity as it’s powerful and relatively easy to use in comparison to the Function or Material Editors that can sometimes be overwhelming. Having said that, some trial and error is necessary in order to get the best results. The main drawback I currently ﬁnd is, in order to get a realistic ﬁnish, it comes at a price – namely, a high render time!