Cross polarisation has long been used to reduce reflections and/either glare on various surfaces. It’s nowadays a common technique used in VFX and Game industry where accuracy and high definition references are needed.
This technique is perfect for capturing the subsurface albedo component of a person and using it as a base texture map. Instead of using a traditional photography that contains both specular and albedo components, this one allows you to directly use data almost immediately, saving tons of cleaning time for Texture and Character Artists.
What’s included in a photo package ?
DNG + EXR raw photography with Nikon official color profile or custom DCP color profile taken with a macbeth color chart. You can open those files with most common 2d packages such as Photoshop, Lightroom with Camera raw (with CR 8.7.1 or above).
Albedo in EXR format that removes unwanted shadow, self-shadow, and occlusion. This derivation also provides an Alpha channel, really useful when painting with The Foundry Mari.
Utility in EXR format contains a melanin, hemoglobin concentration estimation and a fresnel (also known as edge mask) derivation. Those files can be really useful to make special maps such as back scatter, drunk effect, tan effect and much more! Each derivations are stored in a channel where :
Red = Melanin concentration | Green = Hemoglobin concentration | Blue = Fresnel
Working with Mari
Import your images into the image manager.
Make sure you are working in Linear input.
Working with Photoshop
Since EXR is recognized as 32bit by default in Photoshop, you have to convert it into 16bit to be able to work with major tools and blending mode.
Working with Zbrush
Zbrush does accept 8 bit bmp, psd, jpg color image and 16 bit psd, tif gray scale image. In oder to use cross polarized photography properly you will have to convert them before use.
Tips : Copy/paste your folder before applying any conversion process or batch process.