Integration of panoramic hyperspectral imaging with terrestrial lidar data

Abstract

In many close‐range applications it is essential to obtain information about the geometry of the target surface as well as its chemical composition. In this study, close‐range hyperspectral imaging was integrated with terrestrial laser scanning to provide mineral and chemical information for geological field studies. The spectral data was collected with the HySpex SWIR‐320m sensor, which operates in the infrared spectrum between the wavelengths of 1·3 and 2·5 μm. This sensor permits surfaces to be imaged with high spectral resolution, allowing detailed classification and analysis to be carried out. Photogrammetric processing of the hyperspectral imagery was achieved using an existing geometric model for rotating linear‐array‐based panoramic cameras. Bundle block adjustment of multiple images resulted in the registration of the spectral images in the lidar coordinate system, with a precision of around one image pixel. Although the image and control point network was not optimised for photogrammetric processing, it was possible to recover the exterior camera orientations, as well as additional camera calibration parameters. With the known image orientations, 3D lidar models could be textured with hyperspectral classifications, and the quality of the registration determined. The integration of the hyperspectral image products with the terrestrial lidar data enabled data interpretation and evaluation in a real‐world coordinate system, and provided a reliable means of linking material and geometric information.

A Review of Hyperspectral Imaging in Close Range Applications

“…Frame cameras provide a number of key benefits, as they can be used analogously to conventional digital cameras. Thus imaging geometry becomes the conventional pinhole model rather than specialised geometrical models (Kurz et al 2011), and it is possible to image moving objects, as an entire image frame is captured at once. Tripod-based HSI allows imaging of vertical objects and cliffs (e.g.…”

Photogrammetry and Laser Scanning for the Earth Sciencesworking Group V6

“…This can be achieved directly using laser scanning, and for laser scanning projects, integration with imagery is often crucial for adding interpretive value in the form of colour and texture. Indeed, a noticeable trend is the desirability of value-added laser point clouds, where the 3D information is enhanced with RGB (red, green, blue) colour, laser intensity, or multi-or hyperspectral imagery (Franceschi et al, 2009;Burton et al, 2011;Kurz et al, 2011).…”

Close Range Hyperspectral Imaging Integrated With Terrestrial Lidar Scanning Applied to Rock Characterisation at Centimetre Scale

“…In contrast to frame images, the hyperspectral imagery has to be processed with a panoramic camera model to determine the image orientation within the lidar coordinate system (Kurz et al, 2011). A linear-array-based terrestrial panoramic camera model with additional correction parameters, as described in Schneider and Maas (2006), is applied.…”

“…End-member spectra from the Pozalagua quarry, data collected with the HySpex SWIR-320m sensor (after Kurz et al, 2011). …”

“…(Kurz et al 2012). To relate the image to a real world coordinate system, the hyperspectral imagery is integrated with terrestrial laser scanning (TLS) (Kurz et al 2011). The data integration adds geometric information, which may be used for hyperspectral image corrections, for verifying classification results and for analysing the distribution and content of the mineralogy and lithology.…”