Saturday, 28 May 2011
Re - Rendering the clock scene
The Envelope Scene
Vest Uv
Tuesday, 24 May 2011
Texturing the hair
Wednesday, 18 May 2011
UV for the hair object
Sunday, 15 May 2011
Character Renders
Texturing the Character
Clock Render/Problems and Solutions
Monday, 2 May 2011
Glass/ Dielectric Material
When working on Chris’s scene, which included the glass, I realized the importance of Hdri mapping as well as a sky dome. We tried to render realistic glass using a dielectric material. However, when we initially rendered the scene without a sky dome the glass appeared very dark, almost opaque. This was due to two reasons. The first was the fact that we had not created a sky dome, which would help reflect light back to the glass. In Maya when you render a scene everything outside the scene is rendered as black. So we needed some kind of surface or HDRI, which reflected some colour back. This would solve part of the issue. Another technique was to change the ray tracing values so that they could pass through multiple surfaces allowing the majority of the glass to be illuminated causing refractions of light needed for caustics.
Following some newly acquired tutorials we rectified the problem of the glass appearing opaque. However when we rendered the scene a weird oval shape appeared at the bottom of the glass, which looked very wrong indeed. I suggested that Chris change the camera angle as this issue could have been caused by the refractions within the glass at that particular angle. We rendered the scene again and this seemed to do the trick. There are a few more issues that need addressing as the render is far from perfect. However, I am confident that these minor issues can be dealt with in post. Currently there are strong reflections on the surface of the table that look unrealistic in context with the actual illumination in the scene.
When creating Chris's glass scene we wanted the shot to look as appealing and as realistic as possible. The glass material needed to have that transparent quality, while still allowing refraction to take place. We also wanted to replicate caustics, an effect that occurs in reality when light rays pass through glass and are refracted. Refraction is caused by the change in density between air and glass. This effect also causes patterns to form as the light is reflected and refracted inside the glass. Creating this effect in maya can be achieved, however, I needed some tutorials to point me in the right direction.I found a tutorial that showed me how to create a glass ornament using mia’s dialectric material that simulates the refractive qualities of thick glass which is what Chris wanted.
Although the tutorial dealt with a different shaped glass than the one we wanted to use the principles were still the same. At this point in time I was unaware of what material I should be using to create a glass material. I started out by creating a plane that would form the ground plane. I then create the simple glass ornament that was suspended by a tripod. I began following the tutorial rigorously to create the glass material. Initially I applied a blinn to the object that would eventually be the glass. I then opened up the blinns output settings and changed them to a dielectric material that would simulate glass. I rendered the scene but realised that there was no light and no caustics.
Caustics is a way in which Maya simulates the way in which light passes through a glass object and refracts onto a surface. This can be seen when a glass material is light and forms light patterns beneath the glass. To create this effect I needed to flood the scene with photons, which simulate realistic light rays that will help create the caustics effect. First I created a simple area light that will create my primary and only light source. Once the light was in place I created an additional light that would produce the photons necessary for caustics. I then configured all the necessary render settings to render the glass. I was amazed at the result. The photons simulated real refraction perfectly. If we could get the glass in our scene to look this good it would be an achievement. I did realise that the glass did not seem to reflect the white light source. An object that is reflective should show indications of where the light is coming from as bright highlights. I could not understand why this was happening. But I had an idea.
I proposed to render exactly the same scene but changing the glass material to a reflective metal of some kind. By doing this I could acquire some realistic reflections that I could lay over the glass material in Photoshop by compositing individual layers. I did three passes, which included cpolour, occlusion and reflection. Although the renders collectively consumed one day the results acquire would be more than satisfactory. I have discovered that rendering glass with GI and caustics takes considerable amounts of time to render. This is due to the way in which Maya has to do many calculations in order to simulate real lighting. It has to consider material density, reflection, and refraction as well a bounce light. All these attributed increase render time dramatically. Unfortunately I do not posses a desktop computer, which would have sped up the render process. However, the technique proved to be quite effective and the result was very impressive. I will now apply what I have learnt in this tutorial to our scene and adhering to all the necessary render settings and lighting setup to make this render work.
Below are some glass render tests as well as a render for a shot in Chris's film. I was very happy with the results as I had created some very realistic effects. Considering I had no knowledge in creating glass prior to these tests I think I have shown tremendous determination in overcoming these technical obstacles.
Hat Miss
Exterior Shot
The Sig Sauer Shot
I had modeled the pistol very early on in the production process but I now needed to texture it ready for rendering. Setting up the scene was fairly straight forward as I created a plane, which would depict the wooden table in the film. I would rest the pistol as well as the silencer on that plane. I added some fairly detailed textures to the plane that Chris created using Photoshop. The key to the shot would be decent textures, bump mapping and excellent use of lighting. I applied some basic blinn textures to the gun as I had tried previously to add textures, which had some scratches but looked terrible and would add to render time significantly. I implemented a three-point lighting system that would highlight specific areas of interest within the image. I also brought in a blue rime light to give the still shot a more moody feel that added some dynamism to the image. I frequently rendered the image to see if any areas needed changing and that the lighting and composition were correct.
I realized that the scene needed something else to balance the image. The shot itself is an important one, as Frank feels reluctant to continue his trade. The gun is a symbol of his violent crimes and the victims he has killed. I added some bullets in the scene, which not only help focus the viewer’s attention but also brings a sinister element to the shot. I added a brass and copper blinn to the bullets that would reflect light on the whole scene. Initially I was happy with the scene. However, the gun needed some more detail to make it more believable.
The grip needed a bump and at the start I was concerned how I was going to apply it to a specific part of the gun. I had tried several times before to apply a bump but these attempts failed and just looked struck on. I then had a brain wave and decided to construct the bump using Maya rather than acquiring images from the Internet. There is a specific area where the bump needed to be applied that consisted of small interlocking diamonds that would form the handgrip. To do this I opened a new scene in Maya and created several diamonds and cloned them to form a square lattice. I then applied created a camera, which faced these objects directly. I then rendered the scene in 1080p and imported the image into Photoshop so I could convert it to a jpg file that would be small but detailed enough to create a bump sufficient for the grip.
I then opened the Sig Sauer scene and selected the faces necessary for texturing and planar mapping. By planar mapping the grip area I would ensure that the bump, when applied would not stretch. I was very happy with the results as the bump reflected some of the light created from the area light in the scene. I rendered the scene with shadows and I also rendered an occlusion layer in mental ray that would create some ambient shadows in specific areas. I then imported these renders into Photoshop as psd files and began to composite the image. I realized that the gun needed some scratches and dents to imply that the pistol had been used many times before. At this stage the gun looked too shiny and pristine. I used a variety of brushes to add scratches and imperfections, which would make the whole scene more believable. In the final stages of the composition process I added some sharpen filters that would help define the edges of different surfaces and make the overall image crisper. I was very happy with the final result as well as the visual look of the scene. I paid careful attention to the storyboard and constantly had a vision in my mind of how I wanted the shot to look. By having a goal I was able to create a very specific image that would tell part of the story. The rendering did take a long time but this was worth it as the results far exceeded my expectations and the expectations of the director. It was very important to acquire an emotional aspect to the shot that would help tell the story and reflect the emotional struggle of the main character. During this process I learnt that lighting is extremely important in creating a visually beautiful image as well as good composition. But I suppose the most important thing I gained from this little exercise was the ability to use Maya to create textures. I was able to create accurate textures, which could be applied to my models at a very fast rate. I will use this technique in the future, especially when creating repeating patterns.