HDRI (High Dynamic Range Image) lighting was developed to help create more realistic lighting and reflection conditions for matching computer generated images and animations to photography and filmed footage. The technique involves capturing multiple exposures of the same photo by bracketing the exposure time from under exposed through to over exposed. This allows the camera to capture a much larger contast range than can be captured in one photo and tries to mimick what can be seen by the higher contrast ratio of the human eye.
Once the photos are captured (usually between 3 and 8 seperate exposures) they can be merged together into one HDR image or radiance map. This will have much more information than a standard photo allowing it to be used in 3DS max to calculate the lighting for your scene. The HDR image is captured using a reflective sphere or light probe. This allows you to take multiple exposures from a fixed position whilst capturing almost a full 360 degree image of the surrounding environment. This image or light probe (once processed) can be wrapped around a 3D scene and match the same lighting and reflective conditions as the original photo or filmed footage.
The two images below show the computer generated mirrored sphere matched into the original reference photo. At this stage some final colour/contrast adjustments can be made in 3ds max to match the render with the background as closely as possible.
We are currently in the process of creating a christmas animation using this lighting technique, so check back soon to see the finished piece or work.