Chapter 6

Environment

Lighting

Creating realistic sunlight within 3d software has, until recently, been a difficult task to say the least. Present methods of creating realistic sunlight involve either radiosity calculations where the geometry is altered in the background (painful on large scenes!) or global illumination which can be inconsistent within animations, generating image artefacts between frames.

Figure 32 : Dome light setup simulating G.I.

For the purpose of this project it was necessary to create a sunlight system which would give realistic day lighting, a good sunrise/sunset and realistic night lighting. After much experimentation the method employed was based on the dome light setup commonly used to fake global illumination. This is implemented by creating a large hemisphere to enclose your scene; this has a texture of the sky mapped to the inside. A small maxscript is used to position omni lights on each vertex of the hemisphere. The same script is used to sample the colour of the texture at that point and pass this colour on to the omni light present at that vertex. When the scene is rendered it seems to be lit by the sky texture. The final touch was to place a ‘Direct’ light in the scene as a source for the sun.

Atmospherics

After the lighting was setup it was necessary to create an atmosphere within the scene. Sky backgrounds were rendered out in a piece of software called ‘Bryce’, this allowed for different sunlight settings to be created. These were mapped to the inside of the dome light. Finally, a mixture of two fogs was used to give a haze and some horizon noise.

Figure 33 : Various procedurally created sky backgrounds.

3dsmax has the ability to confine volume fog within a helper object, this is very useful if you want volumetric clouds that can be lit by the lighting system and cast shadows over the ground. Unfortunately these clouds add a great deal to the rendering time of the scene.

Foliage

Adding plant life to a 3d scene is probably the 3d artists’ worst nightmare. To get foliage to look right means raising the polygon count in the scene to massive numbers. For distance shots, billboards (a quad polygon with a tree texture applied) will suffice, this increases in complexity the nearer the camera.

Figure 34 : Billboard type trees with non-transparent shadows.

One problem with this method is the shadows the billboard will project; unless you use raytraced shadows (slow!) then the shadow cast will be that of the polygons – not the foliage.

It was decided that for this project, 3d constructed trees would be built to populate the landscape. In the future more testing of different methods will be undertaken.

Additional foliage was placed around the riverside in the form of reeds; again this increased the polygon count within the scene, so the reeds were kept to camera views where possible.

Grass was also looked into to see if it could be used within the scene. Geometric grass was out of the question because of the polygon count, so a volumetric approach was looked into.

Figure 35 : Tests with procedural hair as grass.

Shag: Hair is a plug-in for 3dsmax which is meant to create realistic hair for characters. The same plug-in was experimented with to see if it would distribute hair over the landscape to form grass. Although the plug-in worked it also added considerably to the render time, and as a result, it was reluctantly abandoned.