Image Based Lighting Example

The HDRI map is visible in the background the the reflection as well as the light it emits onto the spheres. However, it is recommended to turn "Primary Visibility" off on the image in order for it not to be visible in the final render.

History of HDRI

In image processing, computer graphics, and photography, high dynamic range imaging (HDRI) is a set of techniques that allows a greaterdynamic range of exposures which is, the range of values between light and dark areas, than normal digital imaging techniques. The intention of HDRI is to accurately represent the wide range of intensity levels found in real scenes ranging from direct sunlight to shadows.

High Dynamic Range Imaging was originally developed in the 1930s and 1940s by Charles Wyckoff. His detailed pictures of nuclear explosions appeared on the cover of Life magazine in the mid 1940s. The process of tone mapping together with bracketed exposures of normal digital images, giving the end result a high, often exaggerated dynamic range, was first reported in 1993, and resulted in a mathematical theory of differently exposed pictures of the same subject matter that was published in 1995. In 1997 this technique of combining several differently exposed images to produce a single HDR image was presented to the computer graphics community by Paul Debevec.

This method was developed to produce a high dynamic range image from a set of photographs taken with a range of exposures. With the rising popularity of digital cameras and easy-to-use desktop software, the term HDR is now popularly used to refer to this process. This composite technique is different from the production of an image from a single exposure of a sensor that has a native high dynamic range. Tone mapping is also used to display HDR images on devices with a low native dynamic range, such as a computer screen.

Fun with HDRI

When working in 3D HDRIs can be useful for lighting purposes. The exposure depth of those images enable the user to set a quick lit scene. Using the Image Based Lighting button in Maya for example, which is found right beneath the Physical Sun and Sky option. This option is only workable in mental ray, not in Maya Software or Hardware render options.
Then click on the folder icon and import the desired HDRI. Furthermore the attributes of the light can then be adjusted as desired.

Outline:

I. Introduction:

A.thesis:

· HDRI are the best images and file format to use when doing image based lighting for 3D modeling and animation. Their multiple layers of exposure make them a prime source for intricate lighting and maximum results.

II. Body:

A. History:

· The desirability of HDR has been recognized for decades but its wider usage was, until quite recently, precluded by the limitations imposed by the available computer processing power.

· Paul Debevec

· Radiance RGBE image file format

B. Synthetic:

· 1997 SIGGRAPH

· "Rendering Synthetic Objects into Real Scenes: Bridging Traditional and Image-Based Graphics with Global Illumination and High Dynamic Range Photography"

C. Tone Mapping:

· limited dynamic range

III. Conclusion:

· HDRI is one of the major advances in the digital world over the last few years and despite certain issues that still exist with compatibility or equipment for example, it still is the now and will be the future of quick, easy, yet great looking lighting, Image Based Lighting.

Week_01; Images & file formats

When up or downloading true HDRI images pay attention to the file format. If it's a jpg it won't give you the wanted result. Make sure that the image you are downloading or using is in the .hdr file format and not a .tiff or .jpg. Here is an example of an HDRI image I have previously used for Image Based Lighting in Maya.


This is how the finished render looks like. The stand is gray and the grass is green but with the effect from the IBL and the .hdr image used it gives it an overall "sunset" look.

Week_01; Process

Since we are all more visual people I found this image that will help explain HDRI and the methode of different exposures a bit better.

This image shows one image taken at different shutter speeds. The shutter speed of the camera will determine the high and low lights of the picture. The slower the shutter speed, the more dark the camera can pick up, the faster the shutter speed, the more light will be exposed onto the film. Compiling those different exposures onto the same image will the result in a High Dynamic Range Image, or HDRI.

Week_01; The HDRI Handbook

Week_01; What is HDRI?

High Dynamic Range Imaging is a method to digitally capture and edit all light in a scene. It represents a quantum leap in imaging technology, as revolutionary as the leap from Black & White to Color imaging. If you are serious about photography, you will find that HDRI is the final step that places digital ahead of analog. The old problem of over- and underexposure in analog photography, which was never fully solved, is elegantly bypassed here. A huge variety of subjects can now be photographed for the first time ever. HDRI emerged from the movie industry, and was once Hollywood's best kept secret. It is now a mature technology available to everyone. The only problem was that it was poorly documented until now. The HDRI Handbook is the manual that was missing. I don't have the book or have look at a copy, but it may be worth investing in it if you are really interested in how HDRI works and all the in's and out's of this methode.