3. Computer Graphic Technical Feasibility
The following addresses the technical issues related to the computer modeling and rendering for the IMAX film:
Gaudi's vision for the Sagrada Familia involved the creation of a highly complex geometry. Modeling of the interior will result in huge 3 dimensional data files with complex curves. All models will be constructed in CADDS 5 by Computervision, a pioneer in computer-aided design and computer-aided manufacturing located in Bedford, Massachusetts. This software is one of the few products capable of meeting the demands of modeling the complex forms of Antoni Gaudi. Portions of the Sagrada Familia have already been modeled with CADDS 5, and its appropriateness for this application is fully proven.
The physically accurate simulation of light and materials using radiosity tools is essential for the rendering of the interior in order to maintain the illusion of reality. Using the Computer Vision CAADS 5 models developed by the University Politecnica de Catalunya and Deakin University, MIT will assemble, optimize and prepare them for a format capable of radiosity based visualization computation. Since massive data files for the complete interior will result, the model will be broken up into separate discrete sections to be rendered as stage sets at resolutions of up to 3000 by 4000 pixels. Texture of materials will be photographed from the Sagrada Familia construction site, and scanned and manipulated to create high resolution texture maps. MIT researchers will investigate the use of a combination of photographic texture maps and procedural shaders written specifically to simulate naturally weathered materials, and effects such as dust motes in shafts of sunlight, depth of field blurring, and the accurate reverberation of sound will be incorporated when useful. A series of multi-processor workstations will be assembled to accomplish this task.
1. Computer Graphics Resolution: The theoretical maximum pixel resolution for film recording of IMAX digital images is 8K wide. Mr. Gord Harris (Director of Film Technology at the IMAX Corporation in Mississauga, Ontario) has indicated that no IMAX film to date has been rendered at 8K, and the IMAX Corporation has not even established a budget for such work. Mr. Harris has advised MIT that resolution of images 4K horizontal is appropriate for this project and would result in excellent quality for IMAX projection. The film L5: First City in Space, currently playing at SONY IMAX 3D theaters, for example, was rendered at this resolution. Since the Sagrada Familia CGI work will employ radiosity technology far more computationally expensive than L5: First City in Space, renderings at higher resolutions would be prohibitive.
2. Rendering Time: MIT researchers have conducted an experiment with a partial CAD model of Sagrada Familia, which Professor Mark Burry of Deakin University provided for testing purposes. From its result, we have estimated an minimum rendering time required for a professional quality image of 4K resolution to be 44 hours on a workstation class computer with a 300Mh CPU and adequate RAM (at least 1Gbyte). The software we used for testing was Lightscape Radiosity/Raytrace system. A global radiosity solution, taking several days to calculate, is required for each partial model to be rendered.
3. Frame Rate: The IMAX film will be rendered at a rate of 24 frames per second for each of two stereo passes. Therefore, 48 frames per second required. For 3 minutes of IMAX 3D computer graphic film, the total number of resulting frames is:
48fps x 4 min. x 60 sec = 11520 frames
4. CPU Requirements: From the information above, we have estimated that approximately 120 processors will be necessary to complete the renderings in 6 months. Each CPU should carry at least 1 GB of RAM in order to compute the frames without disk swapping.
(44 hours x
11520 frames) / (24 hours x 30 days x 6 months)
= 117 processors
5. Disk Storage Requirements: Space For a standard NTSC size frame, a non-compressed image requires approximately 1Mb of disk space. For 11520 of 3K resolution image, approximately 250 Gb of disk space is required, depending on the compression technology employed:
11520 frames x 1Mb x 22 = 25344 Mb (253Gb)
6. Scanning and Film Recording:MIT has established a relationship with the IMAX Corporation in Mississauga, Ontario, who will provide scanning and film recording services for the project.