Archive | Lighting & Rendering RSS feed for this section

Rendering techniques

12 Feb

Global illumination

What global illumination is?

The global illumination

Ambient Occlusion

What ambient occlusion is?

Ambient occlusion

Multipass rendering

Why?

Multipass and morphing camera in AE

Special techniques:

Depth of Field

Motion blur

Blurry reflections

The Art of Rendering

16 Feb

Rendering is the process in which the 3D scene is calculated and rendered to create a 2D image(s). The computer produces a flat picture of the view through the camera for a still image of each sequential frame of the movie. It takes into account lighting, reflections, shadows, and all the other influences of the environment. The process is often a delicate balance between the level of quality you must have and the time it takes to render the project.

General

Render Engine

Full Render – will use C4D or the Advanced Render engine to output a high quality render

Software Preview – the scene will render as it looks unrendered in the viewport

Hardware preview – the scene renders as it looks unrendered in OpenGL display mode

CineMan – allows access to other render engines such as Render Man

Output

Resolution

This is where you set the size of your still frames in pixels. Select the image size needed accordingly to your final output medium. (HDTV 1080 24- 1920×1080 in our case) In the viewport you can set the Render Safe borders to be on or off, so that you can see exactly which areas of your work will show up in your final render.

Check that the Frame Rate is set to 24 or 25 frames per second and that the Frame Range is set to Manual. Then you can specify the Frame range start (From) and end (To) frame yourself.

Save

First of all, if you want to render your frames and store them, the save-tab needs to be checked on. Then you can specify the path in which folder you want your frames to render.

When rendering an animation, it is important to create a folder for the frames. Otherwise you end up doing a lot of housekeeping later on with all the frames that get splattered all around your desktop. Save your frames as preferred file format and select the naming option filename.0000.tiff.

Alpha Channel

Check on Alpha box if the image needs to store an Alpha channel for a further compositing work. The entire alpha channel is masked if you use a Sky, Floor, Foreground or Background object in your scene. Do not use any of these objects if you need the alpha channel.

Dithering is a process that adds a random pattern to colors to prevent color banding. Although dithering enhances the image quality, it also increases file size. For web graphics in particular, you may want to disable dithering to reduce image file size.

Compositing Project File

The Compositing Project File option ensures that all Multi-Pass renderings can be consolidated easily and combined with the correct layer copy mode in the project file, without having to import all assets and channels individually. Additionally enabling the Include 3D Data option will pass this information on to the target application, ensuring that cameras, lights and layers are included. Of course this option can be left disabled, if desired. In our example, our scene will be subsequently edited in After Effects CS4. Therefore, select After Effects as the Target Application.

Multi-Pass

This option is a powerful tool if you are compositing the rendered frames in After Effects later on. Multi-Pass allows you to render different artistic possibilities at one time, and then have them as separate layers in the compositing program. You can specify, which elements to include to your multipass render from the Multi-Pass menu at the top of the Render Settings window. (if you’re only interested in the multipass image, you can disable the Regular Image in the Save options) H.264 files do not support Multi-Pass.

When using multi-pass in rendering it is best to use a linear workflow to ensure the colours are shown correctly. Make sure the linear workflow continues in the compositing software you use. Here is how it works.

Tutorial on lightening up your renders.

Anti-Aliasing

When antialiasing is off, the corners of the pixels on the edges of the polygons can appear jagged. When you are test rendering, the setting None is fine and will save time. In the final render, set the quality to be Best.

Min Level defines the minimum number of sub-pixels that will always be rendered. The default value of 1.1 will suffice for most cases. If, however, artefacting should occur in very detailed regions, e.g. shadow elements get swallowed, higher values should be used.
Max Level is the sub-pixel dispersion that is applied to critical regions (mostly high-contrast regions, i.e. color edges or object edges behind transparencies). This value can, for example, be increased when rendering glass to ensure the rendering of finer details. In an average scene with a Threshold (Color) value of 10%, about 40% of all pixels will be affected, whereas a Threshold value of 5% will result in 90% of all pixels being affected. A value of 0% will cause all pixels of a rendered image to be antialiased – including superfluous regions. This can significally slow down your render time.

Render Tag

Note the Render tag in conjunction with the above.
This tag can be used to define antialiasing settings on object level. In the Edit Render Settings menu, set Antialiasing to Best and the Min/Max Level values each to 1×1. This reflects the least amount of antialiasing for the entire scene (i.e. none). You can, however, use Render tags to define the amount of antialiasing each object should have individually. This lets you, for example, apply a high level of antialiasing to prominent foreground objects and progressively less to objects that lie correspondingly further in the background.

In the Filter pull-down menu, choose the Animation filter for the movie project, which will result in smoother edge, which is less prone for flickering. (Allows the Softness to be controlled by a value  for a customizable effect)

Options

Ray Treshold – Only a small precentage of the processed rays feed into the overall color and brightness of the final render. Any ray that falls under the precentage will be left out and the render times can be greatly reduced.

Ray Depth – Determines how many transparent objects, including those made transparent by the use of Alpha Channels, can be penetrated by the renderer. A low value can speed up the render. Too low value can result in transparent objects rendering black and there is a need to raise the value.

Reflection Depth – Determines the shadow depth calculated for the visible shadow rays. A value of 15 is usually suitable unless you have many transparent, reflective or refractive elements in your scene. Then you need higher value.

LOD (Level Of Detail) – can help reducing render time by lowering the subdivision level at which objects will be rendered. Can be lowered per object through using the display tag.

Bucket sequence and size – If you have a very powerfull machine, you may increase the rendering time by raising the bucket size.

OPTIMIZING THE RENDER

Five Likely Render Hogs

  • Global Illumination
  • Ambient Occlusion
  • Anti-Aliasing
  • Blurry Reflections
  • Area Shadows

Link to a tutorial on optimizing your scene

Camera

15 Feb

It is possible to create as many cameras as you need in c4d and animate their rotation like any other 3D-object.

When you create a camera, the physical location and orientation are represented by a camera symbol. The x- and y-axes of the camera correspond to the film plane, and the z-axis is the direction in which the camera is pointing. The pyramid of linesindicates the camera’s field of view, and the orange handles let you make adjustments to the camera interactively.

Camera and it’s features are fully animatable, but do keep in mind that camera represents the eye of your viewer. It is generally a good idea to keep camera movement simple and smooth, so viewers are not distracted by it’s movements as they focus on the subject. Unless you are animating a roller coaster ride from a point of view of the viewer, try to avoid jerky camera movements by keeping keys to a minimum, placing keys far enough apart in time and space, and using tangent handles to create elegant arch of motion.

The virtual camera has got the same features as their real-world counterparts.

Camera Features

Focal length – polttoväli

Film Gate

Depth of field – syvyysterävyys

Field of view

Focus distance – see Focal legth

Focal length can be adjusted to a wider or narrower angle of view, affecting how much is included in the scene. Changes in focal length will distort perspective, while moving the camera object keeps the perspective normal.

F-stop

Exposure

ISO

Shutter speed