Oral Contribution (O5.2) Bruce Berriman (Caltech/IPAC-NExScI)
Theme: Data visualisation from line plots to augmented & virtual reality
Creating High Quality All-Sky Visualizations of Astronomy Image Data Sets: HiPS and Montage
We describe a case study in creating all-sky maps compliant with the Hierarchical Progressive Survey (HiPS) sky-tesselation scheme in all four bands delivered by the WISE mission. These maps are intended for consumption by immersive visualizers that support panning and zooming across the sky to progressively smaller scales. Initial work led by CDS has shown the value of the approach. We have developed a scheme for creating HiPS-compliant maps that reveal the science content of the images in much greater detail than has hitherto been possible. This has been done by exploiting two unique (to our knowledge) characteristics of Montage: background modeling to rectify the time variable image backgrounds to common level; and using the adaptive image stretch algorithm to convert the image data to display values for visualization. In this case study, we have created multi-color and single-color HiPS maps for all four bands of the WISE all-sky survey, down to survey level 9 tiles, level 18 pixels (~1 arcsec). The creation of the maps involved use of existing Montage tools to reproject all the WISE images to produce HEALPix-compliant mosaics, on which HiPS is based, followed by development of new tools to cut-out the HiPS tiles from the HEALPix maps. The compute intensive part of the processing lies in the reprojection, and we show how we optimized the processing for efficient creation of the mosaics, used in turn to create the HiPS tiles, and for correct handling of image backgrounds.
