The innovation is a powerful Ultra-Compact High-Definition Hyperspectral Imaging System (UC-HDHIS) for UAV deployment. UC-HDHIS concurrently acquires pushbroom hyperspectral imagery using a grating imaging spectrometer, and framing multispectral imagery using four-selectable-band CCD cameras, along with synchronized sky spectral irradiance measurements. Adapting miniaturized optics, camera and computer components, positioning/attitude measuring devices, and real-time software suite into a modular design, UC-HDHIS is highly configurable with a variable mass 3-15 lbs and a variable volume 125-650 cubic inches. Its CCD hyperspectral module covers 400-950nm spectral range with a spectral resolution better than 2.5nm and a swathwidth better than 752 pixels, which is extendable to 400-1700nm by docking an InGaAs module. The multispectral imaging format is 1024x768 pixels. Minimum quantization depths are 10 bits for hyperspectral and 8 bits for multispectral imagery. Using CompactFlash as mass storage and a special real time recording technology, UC-HDHIS has no mechanically moving/rotating parts and is rugged and vibration-resistant. A dual-Earth-imaging feature calibrates and compensates each part for better radiometric and geometric measurements. With mission automation and simultaneous Earth/sky spectral imaging and position/attitude sensing appended to the hyperspectral/multispectral data, high-quality geo-referenced spectral images are obtainable by a small UAV.