Making Of 'Corner of Cobblestone'
Wade Muller, a Master's degree art student from the University of Sydney, Australia, shows us how to build 'Corner of Cobblestone' from scratch...
The idea for this project was to create natural textures and to experiment with V-Ray Sun. I will explain more about V-Ray Sun and the lighting I used later on in this article. The original reference image was taken of a building in my local area, Coogee, in Australia. The reason I chose it was because it had slightly dirty walls, but they were not to the point of being filthy. It was also interesting compositionally, and allowed me the ability to play with different lighting setups (Fig01).
For the modelling of the main building faces I used simple planes, then cut and extruded them to achieve the shape that I wanted. This also came in handy when I progressed to texturing because the faces were already separated. I split the building into three main parts; Left Main Face, Corner, and Right Small Face. All extra modelling was created using box modelling. There were certain areas where modelling was not used; instead I used either displacement, or a mixture of bump and opacity, textures to give form to such places as the balcony fences and the cobblestones (Fig02a - b).
Firstly, as I mentioned above, I used textures to create form, instead of modelling. The first area where I used this technique was the cobblestones, which are a V-Ray displacement. I just used an image and tweaked it in Photoshop so that the contrast was correct to displace the stones properly. The second area was the balconies, where I used a mixture of bump and opacity textures, instead of geometry, because they were placed far from the camera, and so in the light of scene poly efficiency I could get away with it. As you can see in the bump, all I did was take the opacity map and feather the edges. This allows the fence to appear rounded, similar to how it would have been forged in a metal workshop (Fig03 - 05).
I then moved on to work on the glass in the front door, for which I wanted to achieve a foggy, bumped effect. So I simply applied a bump map to the normal glass that I made (Fig06).
The main building texture was created by tiling a brick texture in Photoshop, then cropping and arranging extra components, such as the brick arch. Finally, some dirt maps and colour maps were overlaid to achieve the dirt and mottled colour (Fig07 - 08).
Lighting and Scene Setup
As you can see from the scene setup in (Fig09), I did not model any of the back of the building, as this was a still render and therefore seemed rather pointless to do so. For this project I chose V-Ray as my renderer, which became important in terms of the lighting because I used V-Ray lights as well as V-Ray shadows to complete the scene. So firstly, before getting into all the all nitty and gritty details with the V-Ray setup, I would like to explain some of the lighting theory behind the project. This may be helpful to anyone who has not used V-Ray, or any render system that is based on a Global Illumination (GI) setup, before.
The two main components I commonly use when lighting an exterior scene are GI and a Key light. The reason for doing so is actually based on the real world. GI is basically reflected light, or light produced from the general surroundings. This system in based on shooting photons at the scene, and the bounces of light off objects and materials generate a general,
non-directional fill of the scene. GI is basically a Fill light. In the case of this project I influenced my GI, or Fill, with a colour, and this was provided by a High Dynamic Range Image (HDRI). An HDRI is an image that has more data stored within it, and contains colour information that can be transformed into coloured light.
coming through a stained glass window. The Key light provides the main illumination of the scene, indicates light direction, produces shadows, and also generates GI. In this project the Key light was the sun, as well as a tool to produce the HDRI, however I will explain the V-Ray settings used in a moment. In conclusion, it comes down to a simple formula: Fill + Key = Final Result. However, this formula does take some balancing and can often involve constant re-rendering. There are ways of speeding this process up however by using compositing software and by rendering separate light passes to see what the correct value is, which unfortunately is a whole different tutorial just in itself. As I mentioned earlier I used a feature in V-Ray 1.5 called V-Ray Sun, which replicates the sun's natural lighting. V-Ray can be very precise and, in this case, you are able to control the strength of the sun as well as the ozone, and many more aspects that are based on real world physics. V-Ray Sun can also be used to create a sky texture. This feature actually creates the sky based on where the V-Ray Sun is in the scene. For example, if the sun is just above the horizon it will create a sky that goes from yellow to orange to blue. However in this particular project I did not want to use that sky in the shot, but rather wanted to use it as an HDRI to both light and slightly colour the scene. Using this method I could achieve very photorealistic lighting without having to play around with sky domes or other methods of Fill lighting. The V-Ray plane in the scene helped with GI reflection and was mainly used to simulate that there was a constant ground in the world I was creating (Fig10).
The render was a basic setup for exteriors. I had the primary bounce with an Irradiance Map and the secondary with Quasi Monte Carlo. I also used a V-Ray Physical Camera, which is a very handy tool that allows me to control the exposure and the aperture; basically, allowing me to control the brightness and contrast in the image, even before post work.
Finally I added the sky that I wanted in Photoshop, and made some major contrast adjustments. I'm a big believer in getting the image as close to perfect before Photoshop, as it makes you work harder at how the image is looking, and how your CG lights are affecting the scene (Fig11).
I hope this article has been helpful to some people. If you have any questions (or job offers), please contact me.