Panorama Software - Panoweaver Success Story

A Solution of Making Panoramic Environmental Images in Movie

In ancient Greece , the passion of two of literature's most notorious lovers, Paris, Prince of Troy and Helen, Queen of Sparta, ignites a war that will devastate a civilization. When Paris spirits Helen away from her husband, King Menelaus, it is an insult that cannot be suffered. Familial pride dictates that an affront to Menelaus is an affront to his brother Agamemnon, powerful King of the Mycenaeans, who soon unites all the massive tribes of Greece to steal Helen back from Troy in defense of his brother's honor. That's the story of this summer's blockbuster ?movie "TROY".

Among this film, so many new techs were used. Here I'd like to introduce one on Image Based Lighting & Rendering.

Framestore CFC was formed in December 2001 through the union of two of the most creative and dynamic companies in the industry: Framestore and The Computer Film Company (CFC). The company is now the largest visual effects and computer animation company in Europe, with over 30 years of combined experience in digital film and video technology. The company has won numerous international awards including two Technical Academy Awards from the Academy of Motion Picture Arts and Sciences, and eleven Primetime Emmy Awards.

Project:
Troy

Solution:
Easypano Panoweaver 3.01 Professional Edition

Background:

Framestore CFC recently used Panoweaver® 3.01 Pro on the epic movie "Troy" to stitch the images together to form the HDR* images and environment maps. All the HDR images and environment maps were then integrated into shaders designed to incorporate Image-Based Lighting and standard CG lighting. The film opened on 14. May 2004 in the US and 21. May in the UK , starring Brad Pitt, Eric Bana, Orlando Bloom, Diane Kruger, Sean Bean, Brian Cox, Peter O'Toole, Saffron Burrows and Julie Christie. Directed by Wolfgang Petersen, written by David Benioff and produced by Warner Brothers, the film has thus far solidly outperformed many of its rivals at the box office worldwide.

Benefits:

• Increases user productivity.

• Cuts development time and Quality Assurance testing time by half.

• Greatly improved the quality of HDR images and environment maps.

Project Details:

"I like Panoweaver because it is easy to use and has a great deal of controls over the stitching process. This gives the best result for the final image. Then we can get high quality HDR images and environment maps, easily and effectively', Ian Frost of Framestore CFC explained, 憌e take several different exposures with the fish eye, when all the images are layered the resulting image is a high dynamic range floating point image. This means that if we multiply the image with a low number we can see only the bright parts, i.e. the sun. If we multiply the image by a high number we can see all the detail in the shadows. This can be very useful for lighting 3D objects into a real life scene."

( High Dynamic Range images)

Framestore CFC is one of the only two houses in London who could - technically and experience-wise - handle scenes of the complexity and scale the film's VFX Producer envisioned. In this film, it dealt with the action from the Trojan beach landing and back across the ocean to Greece .

The problem was that it needs 16 pictures taken from two angles* with 8 level of exposure to form one single HDR image above. While they were going to have a variety of difficult locations on set, a quicker way of capturing HDR images and environment maps was needed. You may also notice that there is some distortion, as well as much ghosting.  Although the compositing method gets rid of the major part of the distortion, it doesn't get rid of the overall distortion at all.

"I was not overly enamored of this technique," says Thum, "It's cumbersome, time consuming, it gets in the way on the shoot, imperfections in the ball can cause problems and it gets fuzzy round the edges." Thum's search for a better solution led him to develop a system that employed a Canon 1DS digital camera with a Sigma 8mm fisheye lens and Panoweaver ?the panorama stitching software of Easypano. It shot five bracketed exposures looking north and south, and then Panoweaver may easily combine these images into panoramas, which may be taken as the environmental data as needed. The test results were excellent, giving Thum and his team a highly accurate, non-intrusive means of capturing vital shot lighting information.

    
(Fish eye images taken by Canon 1DS and the output of Panoweaver)

Introduction of Thum's Solution

Hardware

Canon EOS 1DS, Sigma 8mm f/4 EX Circular Fish-Eye lens, Manfrotto 303 Quick Time VR pano head.

Software

	Easypano Panoweaver 3.01

Solution Canon 1DS digital SLR was particularly good as it has a full 35mm CCD back plate. This meant that they could attach a Sigma 8mm fisheye lens to it and photograph the full image with negligible artifacts. The Canon camera also allowed them to program the bracketing, so that it automatically took five shots at varying F-stops with just one shutter release. The result is a rig that took just 20 seconds to capture a full HDR environment map at any given location. Then they used Panoweaver ?kind of dramatically easy-to-use and highly cost-effective software to stitch the images together. Just easily import the images and click 慳uto-stitching' button. It will be all set in less than one minute. They may then integrate all the HDR images and environment maps into shaders designed to incorporate Image-Based Lighting and standard CG lighting.

The Use of Panoweaver

Panoweaver provides an easy and powerful way of creating a panorama and brings peole to the full immersive virtual world with 360*180 degrees field of view. As an easy-to-use, versatile and cost-effective spherical and cubic panorama creating tool, it is more and more popular among newbies and insiders. Here let's take the "hot" epic movie "Troy" for example to try to make an environmental map with Panoweaver.

Click File > Open Hemisphere Image or click on the toolbar to open hemisphere images, either single, two or three.

When stitching two fisheye and three fisheye images, Panoweaver provides the function to convert from spherical stitching to cubic stitching and vice versa.

Click Panorama > Spherical/Cubic Conversion or click the button and on the toolbar to convert between spherical stitching and cubic stitching.

Click Panorama > Auto Stitching or on the toolbar to stitch the panorama autom atically.

As stated above, Panoweaver allows you to optimize the variation in FOV, yaw, pitch, and roll in shooting. If you are not satisfied with the auto stitching result, manual stitching is available. In manual stitching mode you can visually adjust the three parameters and determine the exact value for FOV, yaw, pitch and roll thus to get a satisfactory result.

Click Panorama > Manual Stitching or on the toolbar to stitch fisheye images manually.

Click File > Save or on the toolbar to save the stitched panorama image.

• Save: Fill the file name and choose the appropriate format ( *.JPG,*.BMP,*.PNG,*.TGA,*.PSD , etc.) and then click Save .

• JPG quality control: When choosing *.JPG as the format, a dialog appears:

Move the slider with the mouse or the arrow keys on the keyboard to adjust the Jpeg quality. The result can be previewed in the area of Compressed Image with respect to the Original Image. The Jpeg quality affects the image size a lot, so please choose a value on the basis of the file size and image quality (75 for Jpeg quality value is recommended for general user).

2:1 equiretangular image (spherical edition)	1:6 cubic image (cubic edition)

Now an environmental map has been completely finished and may be then imported into shaders designed to incorporate Image-Based Lighting and standard CG lighting when necessary.

Notes:
1. High-Dynamic Range (HDR) image:
The "dynamic range" of a scene is the contrast ratio between its brightest and darkest parts. A plate of evenly-lit mashed potatoes outside on a cloudy day is low-dynamic range. The interior of an ornate cathedral with light streaming in through its stained-glass windows is high dynamic range. In fact, any scene in which the light sources can be seen directly is high dynamic range.

A High-Dynamic Range image is an image that has a greater dynamic range than can be shown on a standard display device or that can be captured with a standard camera with just a single exposure. It is typically generated by combining multiple normal images of the same scene taken with different intensity levels, or as the result of creating a global illumination rendering.

2. The "Dead Spot" behind the Mirrored Ball is at the root of the most severe of the distortions you will likely encounter.  When you run a Mirrored Ball image through HDRshop® to create a Latitude/Longitude panorama, it assumes that the Mirrored Ball actually sees the full 360° of the environment and will create the Latitude/Longitude panorama accordingly. This assumption that the Mirrored Ball reflects the full 360°, whilst it may only reflect 320°, is what causes a particular distortion ?pinching.

What is often proposed to get rid of this distortion, as well as reflections of the photographer, is to take two pictures of the Mirrored Ball , at 90° offsets, as depicted in Figure below.  This way the full 360° of the environment can be captured, as what is 'behind' the Mirrored Ball when seen from one camera angle becomes to the right, or left, of the Mirrored Ball when seen from the other camera angle.  Using the results of these two pictures, one can them composite one over the other to get rid of the distortions, and photographer.

By this way, the main distortions as well as the photographer's reflections are gone. However, there is still some distortion, as well as much ghosting.  Although the compositing method gets rid of the major part of the distortion, it doesn't get rid of the overall distortion at all.

(from http://www.debevec.org)