Visualization Tools for Remote Sensing Data

Pushing the limits of current remote sensing (RS) instrumental sensitivity and resolution, state-of-the-art image processing techniques applied to coronal imaging data from extreme ultraviolet (EUV) and white-light (WL) coronagraph instruments can overcome faint signals and noise in data.  In the past few years, we have developed a series of techniques that have proven to be crucial in linking the low to high corona and has facilitated the interpretation of in situ data.  Uninterrupted views of the solar atmosphere from the solar surface to the outer corona can be obtained, with due limitations, by combining available multi-instrument and multi-observatory RS observations. Our advanced image processing techniques can then reveal structures (on various scales) in both EUV and WL data, namely: the NRGF technique, which reveals radial structures of the corona; the MGN technique, which enhances the contrast of multiscale features (mostly in EUV observations); the DST method, which separates dynamic and static features in WL; the BFF method, which isolates specific time scales of brightness variation.  Depending on the type of observation and science question, these techniques can be combined to reveal the feature and properties of interest.  Additionally, we have developed semi-automatic procedures of feature recognition in RS observations, namely: the persistence mapping tool, which can track the outmost profile of CMEs during their propagation; the non-radial methodology, which can identify the streamer boundary in EUV/WL composite images.  The latter method was also used to define non-radial height-time plots, which, in combination with some of the previously described techniques, provided the possibility of continuous tracking of brightness enhancements from the coronal base out to the radial extended corona (mostly STEREO/SECCHI suite).  Limitations due to line-of-sight (LOS) effects, inherent to RS observations, have also been addressed with time-dependent rotational tomography able to derive coronal density distributions.  Combination of the non-radial method and tomography reconstruction have also enabled the development of a visualization tool to test if propagating features are due to real transients, or the rotation of finely spaced density rays that are structurally static and rotate with the Sun. Here, we provide an overview of these techniques with examples of application to specific science case studies.