3D Computer Rendering

1
3D Computer Rendering

• Kevin Ginty
• Centre for Internet Technologies
• www.cit.sunderland.ac.uk

2
Welcome!
3
Overview

• The Sunderland Grid architecture
• The rendering process
• Four rendering applications trialled
• Emerging themes and common issues
• Grid rendering demo

4
Grid Architecture

• 40 compute nodes (plus 2 head nodes)
• runs Linux and Windows 2003 Server
• each node has
• 8GB RAM, 2 dual core processors 2.66GHz
• 250 GB local scratch disk
• 3 x 1GB network cards

5
Grid Architecture

• Entirely self contained network
• Cisco 6500 series router
• 10 high specification workstations
• VoIP switchgear
• Scali grid management software (Linux)
• Windows 2003 Server Compute Cluster Edition
  (incorporating Grid administration)
• Can run either system
• Different parts of the grid can run different
  operating systems i.e. some nodes can be running
  Linux while the rest are in Windows 2k3 CCE

6
Uses of rendering

• Rendering applications are used for generating
  graphics, animations and simulations for
• Cartoons and movies (e.g. Toy Story, Star Trek)
• Industrial models
• TV advertisements
• Walk-through simulations for architects designs

7
The rendering process

• Begins with a 3D model, known as a wireframe
• Surface colour and texture detail for the object
• Background information (may be photographic)
• Light source and direction
• Camera angle(s)

8
The rendering process

• Algorithms are then used to model the motion of
  the object(s) against the background, frame by
  frame
• Each frame is then completed by filling in the
  areas on the wireframe with the colour and
  texture data
• Each frame can take a long time to render from
  several seconds through to several minutes
• Frames are assembled into a movie file, and saved
  at the appropriate resolution

9
The rendering process - interface
10
(No Transcript)
11
The rendering process camera angles
12
The rendering process - wireframe
13

• AVIs

14
Rendering Applications

• Four rendering applications were considered,
  three commercial and one open source-
• Autodesk 3DS Max
• Maxon Cinema 4D
• NewTek Lightwave
• Blender

15
Uses of rendering

• Rendering applications are used for generating
  graphics, animations and simulations for
• Cartoons and movies (e.g. Toy Story, Star Trek)
• Industrial models
• TV advertisements
• Walk-through simulations for architects designs
• Examples (run avis)
• Robot
• Apache
• Guildhall

16
Rendering Applications - comparison

• Autodesk 3DS Max the most widely used
• Blender is an open source alternative
• All four accomplish essentially the same job
• Differences in performance, arising from
  differences in modality and use of system
  resources

17
Rendering applications common issues

• In order to run on the grid, frame rendering
  operations need to be farmed out to the compute
  nodes, processing carried out there, and the
  results collated afterwards.
• Rendering applications have therefore to
• Transfer data to the nodes
• Run processes, either locally installed on the
  node or executable code copied across at run-time
• Transfer the data back to a central location to
  be collated afterwards
• Scheduling work on the nodes
• Needs to be handled efficiently
• Rendering applications like to use the high
  performance graphics adaptors found in
  workstations (but not in servers!)

18
Rendering applications data transfer

• One node (or workstation) manages the operation
• Data can be copied to and from the node
• Directly from the workstation (may make a
  bottleneck on the workstation due to disk access
  times, and processor time spent on handling the
  file copying across to lots of nodes)
• From a third point on the network acting as a
  data store (e.g. Network Attached Storage) which
  is better because the controlling node or
  workstation is not tied up most of the time on
  data transfer
• Using mapped drives or UNC paths (Uniform Naming
  Convention) where the operating system handles
  the accessing of remote logical drives.
• Transferring the files using dedicated processes
  and the nodes ip connections

19
Rendering applications data transfer

• Operationally, the tidiest way to do it would be
  via dedicated processes, and ip connections,
  using NAS storage
• In practice, few rendering applications support
  all of this
• NewTek Lightwave uses UNC paths to copy the data
  files back to the control node which gets into
  trouble with the 10 connection limit for mapped
  drives in Windows XP

20
Scheduling tasks on the compute nodes

• Efficiency varies enormously
• Some applications (3DS Max) schedule quite well,
  and make fairly good use of available resources
• Others (Blender/YADRA) schedule on the next free
  node, and count along from the beginning each
  time, meaning that nodes later in the sequence
  dont get used unless the render operation takes
  a long time (and the earlier nodes are busy for
  longer)
• Lightwave clicks along the list of nodes,
  scheduling the next one every 3s or so,
  regardless of how long the jobs take, or whether
  or not the previous nodes have completed their
  tasks already so if a render takes 12 seconds,
  only four of the nodes will ever be in use.

21
Rendering applications OS environments

• Most rendering applications specify Windows XP,
  with some using Vista and occasionally servers
• Desktop environments like XP are preferred by the
  applications because
• Desktop boxes have high performance graphics
  adaptors
• XP has the drivers
• Server OS tend not to support powerful graphics,
  and may not have drivers for high performance
  graphics cards
• Server hardware is usually configured so as to
  provide maximum support to the network adaptors
  and disks, and not the display drivers
• But

22
Rendering applications OS environments

• Copying large amounts of data over the network
• Managing large numbers of simultaneous
  connections (mapped drives or otherwise)
• are much better handled by server operating
  systems, which are designed to do so

23
Rendering applications OS environments, and GPUs

• Microsoft are currently considering this problem,
  as a range of applications (not just rendering)
  are utilising the computer power of the high
  performance graphics adaptors now found in most
  workstations
• Solutions-
• MS build the drivers for the cards into Server
  2008 !
• Start making server hardware that handles high
  performance graphics as well

24
Questions

• ?

25
Questions

• Thank you!
• Kevin Ginty
• kevin.ginty_at_sunderland.ac.uk