Measurement Geometry Basics: Introduction

Measurement geometry plays a critical role in the definition of object colors. The reasons for selecting one geometry over another are many, and we cannot explore all the details here. For now these pages explain how each geometry works. The CIE nomenclature for measurement geometry is Θid. Θi is the angle of incident light (source) and Θd is the angle of detection (collection). There are additional modifiers that better specify the subtleties of each measurement type. These are described on the pages linked below. Bidirectional Geometry (also called 45:0 or 0:45) Hemispherical Geometry (also called d:0,0:d, d:8, 8:d, etc) Alternative geometries (gonio measurements)