Source-linked AI summary
JHelioviewer - Time-dependent 3D visualisation of solar and heliospheric data
D. Mueller, B. Nicula, S. Felix, F. Verstringe, B. Bourgoignie, A. Csillaghy, D. Berghmans, P. Jiggens, J. P. Garcia-Ortiz, J. Ireland, S. Zahniy, B. Fleck
TL;DR
Growing solar data volumes make it difficult for scientists to access, browse, and find interesting observations efficiently. JHelioviewer combines JPEG 2000-based browsing with expanded visualization tools; users have created over 1.4 million movies, and the software offers an initial virtual-camera capability for Solar Orbiter planning.
Problem
The growing volume of solar data, particularly SDO data available from few repositories, makes accessing, browsing, and finding observations efficiently difficult.
Source: §1 · p. 1Method
Results
Over 1.4 million movies have been created since February 2011, and JHelioviewer supports time-dependent 3D solar browsing and real-time image processing.
Source: §15 · p. 13Takeaways & Limitations
Users can browse data from any day of the SDO mission, identify interesting events, and then request archived science data for in-depth analysis.
Source: §1 · p. 2
Abstract
from arXiv · showhide
Context. Solar observatories are providing the world-wide community with a wealth of data, covering large time ranges, multiple viewpoints, and returning large amounts of data. In particular, the large volume of SDO data presents challenges: it is available only from a few repositories, and full-disk, full-cadence data for reasonable durations of scientific interest are difficult to download practically due to their size and download data rates available to most users. From a scientist's perspective this poses three problems: accessing, browsing and finding interesting data as efficiently as possible. Aims. To address these challenges, we have developed JHelioviewer, a visualisation tool for solar data based on the JPEG2000 compression standard and part of the open source ESA/NASA Helioviewer Project. Since the first release of JHelioviewer, the scientific functionality of the software has been extended significantly, and the objective of this paper is to highlight these improvements. Methods. The JPEG2000 standard offers useful new features that facilitate the dissemination and analysis of high-resolution image data and offers a solution to the challenge of efficiently browsing petabyte-scale image archives. The JHelioviewer software is open source, platform independent and extendable via a plug-in architecture. Results. With JHelioviewer, users can visualise the Sun for any time period between September 1991 and today. They can perform basic image processing in real time, track features on the Sun and interactively overlay magnetic field extrapolations. The software integrates solar event data and a time line display. As a first step towards supporting science planning of the upcoming Solar Orbiter mission, JHelioviewer offers a virtual camera model that enables users to set the vantage point to the location of a spacecraft or celestial body at any given time.
1. Introduction
The growth of solar data has made access, browsing, and discovery difficult, especially for SDO’s large data volumes. JHelioviewer addresses these challenges with compressed, on-demand browsing and an expanded set of tools for exploring solar data.
1. Introduction
- SDO returns 1.4 terabyte of image data per day, and its datasets are difficult to download, making access, browsing, and finding interesting data key challenges.The data are available from only a few repositories.Source: §1 · p. 1
- JHelioviewer serves lossy JPEG 2000 image data on demand in a quality-progressive, region-of-interest-based stream and supports full-resolution browsing across the SDO mission.Users can browse data and then request archived science data for in-depth analysis of identified events.Source: §1 · pp. 1–2
- New features include multi-viewpoint 3D display, real-time difference movies, PFSS field extrapolations, timelines, solar-event data, and multiple 2D projections.Multi-viewpoint data can include observations from the twin STEREO spacecraft.Source: §1 · p. 2
- A virtual camera model sets the vantage point to a spacecraft or celestial body at a given time, as an initial step toward Solar Orbiter science planning.The model uses an ephemeris server; the paper also describes added datasets from multiple space missions and ground-based facilities.Source: §1 · p. 2
2. Browsing petabyte-scale image archives
High-cadence solar observations can be impractical to download for browsing, so the Helioviewer Project provides compressed browse data and processing tools to help users locate data of interest.
2.1. Motivation: Why browsing tools are essential
- SDO/AIA produces 16-megapixel images in 10 channels at an average 12-second cadence, while an 800-gigabyte study dataset would take 25 days to download at 3 megabit/s.The authors note that such download times are prohibitive when the dataset has not yet been explored and validated for a research purpose.Source: §2.1 · p. 2
2.2. Data processing approach of the Helioviewer Project
- Less than 9 terabyte per year of browse data supports full-spatial-resolution coverage at about half-minute time resolution.JPEG 2000 compression reduces each 16-megapixel SDO/AIA image to 1 megabyte, and processing every third image across all channels produces that annual volume.Source: §2.2 · p. 2
- The project developed an open-source server-side processing stack using OpenJPEG and Glymur as an alternative to proprietary IDL and Kakadu components.The stack runs on the Royal Observatory of Belgium test server.Source: §2.2 · pp. 2–3
- The application interface combines a 3D image scene with a timeline panel showing 1D and 2D time-series plots, with solar-event markers overlaid on both.The timeline examples include disk-integrated X-ray fluxes.Source: Figure 1 · p. 3
3. Software design
JHelioviewer separates display configuration from rendering and uses an extensible client-server architecture to present solar imagery, models, timelines, and events.
3. Software design
- JHelioviewer is written in Java, uses OpenGL for graphics-intensive computations, and is released under the Mozilla Public License 2.0.The design prioritizes performance, cross-platform compatibility, and supported open-source components where possible.Source: §3 · p. 3
3.1. Architecture
- The architecture separates display configuration from rendering and uses client-server counterparts for image, timeline, model, and event datasets.Image requests use JPIP over HTTP, while metadata repositories support searching and locating relevant images.Source: §3.1 · pp. 3–4
3.2. High-performance graphics processing with OpenGL
- OpenGL can issue commands directly to a computer’s graphics processing units, enabling significant performance improvements over standard Java graphics rendering.JHelioviewer implements graphics-intensive computations using OpenGL and JOGL.Source: §3 · p. 3, §3.2 · p. 4
3.3. JHelioviewer user interface
- The interface places image data and modelled magnetic field lines on the image canvas, with 1D and 2D time series below and SWEK events on both canvases.The left side contains display controls and layer managers.Source: §3.3 · p. 4
4. Interactive streaming of high-resolution image data with JPEG 2000
JHelioviewer uses JPEG 2000 and JPIP to stream high-resolution solar images progressively, with access to requested regions and resolutions. Its server architecture supports concurrent clients, while on-demand indexing avoids building complete image indexes at load time.
4. Interactive streaming of high-resolution image data with JPEG 2000
- JPEG 2000 with JPIP supports real-time spatial random access and progressively displays highly compressed, quality-progressive, region-of-interest image streams.The authors describe this as a solution for making petabyte-scale image archives available to the worldwide community.Source: §4 · p. 4
- JPEG 2000 automatically creates multiple resolution levels, while static image tile pyramids require more total data and more files to manage.The paper notes that helioviewer.org tiles and converts JPEG 2000 images on demand for its 2D canvas, with instantaneous display limited to single images.Source: §4 · p. 4
- The open-source JPIP server combines parent-child processes with threaded client handling to preserve connections after a child-process error and share opened images across clients.The parent retains client sockets and can create a replacement child process; clients in a child process share opened images.Source: §4 · p. 4
- Image indexes are built on demand from client requests rather than completely at load time, saving time and memory.When a connection closes, an image is removed only if no other client shares it.Source: §4 · pp. 4–5
- The client uses the closed-source Kakadu SDK under a non-commercial license for JPIP decompression because it currently offers the best performance.The paper identifies OpenJPEG as a possible future open-source alternative.Source: §4 · p. 5
5. Displaying multi-viewpoint data in 3D
World Coordinate System support underpins JHelioviewer's 3D display of multi-viewpoint solar data. The software can place images using metadata, set virtual viewpoints from ephemerides, and display coordinate grids while retaining the former 2D view under its default projection.
5. Displaying multi-viewpoint data in 3D
- WCS support for STEREO data laid the foundation for JHelioviewer's 3D visualization; solar-surface and low-corona data map onto a sphere, while coronagraph data project onto planes perpendicular to their lines of sight.STEREO's two viewpoints enable stereoscopic imaging of the Sun and phenomena such as coronal mass ejections.Source: §5 · p. 5
5.1. Image placement
- Image metadata determines a default rotation matrix and distance from the Sun, which are applied when the image is displayed..Source: §5.1 · p. 5
5.2. Virtual viewpoint
- Users can set the viewpoint to any celestial body or spacecraft with ephemeris data on the server, enabling simulated-data exercises for Solar Orbiter science planning.The viewpoint is defined by the vector to the Sun from a location at a given time.Source: §5.2 · p. 5
5.3. Geometry server
- The ROB Geometry Server uses NAIF SPICE to compute solar-system positions and returns timestamped camera coordinates; supported locations include planets, selected spacecraft, and comet 67P.The example coordinates specify distance to the Sun and Stonyhurst heliographic longitude and latitude.Source: §5.3 · pp. 5–7
5.4. Display of latitude–longitude grids
- JHelioviewer offers user-adjustable latitude–longitude grids in Stonyhurst, Carrington, Heliocentric Inertial, and viewpoint coordinate systems.Source: §5.4 · p. 7
5.5. From 2D to 3D
- With orthographic projection and no rotation, the 3D display shows the same images as the earlier 2D-only software, without distortion relative to the instrument's tangential focal-plane projection.Source: §5.5 · p. 7
6. Real-time image processing
JHelioviewer performs image processing on the client GPU for real-time interaction. Its features include adjustable image rendering, rotation-compensated tracking, real-time difference movies, and multiple projections for viewing solar data.
6. Real-time image processing
- GPU-based image processing provides real-time features that also improve the user experience.The software uses OpenGL and GLSL for graphics-intensive computation.Source: §6 · p. 7
6.1. Basic functionality
- Users can adjust sharpening, brightness, contrast, opacity, and color tables in real time while high-resolution multilayer movies play above 30 fps.Radial filtering enhances the off-disk corona, and users can toggle off-limb corona rendering; coronagraph occulter masks are also implemented in OpenGL.Source: §6.1 · p. 7
6.2. Solar rotation correction
- Tracking mode compensates for solar rotation by calculating the surface rotation rate at the viewport center's latitude and shifting displayed image subfields during rendering.The calculation uses the empirical formula of Howard et al. (1990).Source: §6.2 · p. 7
6.3. Real-time generation and display of difference movies
- JHelioviewer computes running and base differences for available data in real time on the client GPU, avoiding the need to download and process images or request pre-generated STEREO SECCHI differences.It calculates differences for the current region and resolution, compensating for solar rotation between frames and increasing contrast for visibility.Source: §6.3 · p. 7
6.4. Image projections
- Four image projections—orthographic, latitudinal, log-polar, and polar—provide alternate views that can facilitate visual detection of propagating features in the outer corona.Source: §6.4 · pp. 7–8
7. Magnetic field line rendering
JHelioviewer computes and displays potential-field source-surface magnetic field lines from daily synoptic magnetograms. Its client aligns the lines with image data and offers interactive display controls and multiple solar projections.
7.1. Server side
- A PFSS algorithm was implemented in C for fast computation following the Stanford PFSS model.29 It uses daily synoptic GONG30 full-disk magnetograms in FITS format at 256 × 180 resolution on a sine-latitude grid.The PFSS model uses the current-free approximation, with magnetic field B derived from a scalar potential ψ satisfying ∆ψ = 0.Source: §7.1 · p. 8
- Third-order Adams–Bashforth integration reduces vector-field evaluations compared with fourth-order Runge–Kutta because each evaluation is relatively slow.Source: §7.1 · p. 8
7.2. Client side
- The client asynchronously caches up to 125 FITS files and rotates field lines to align with image data using a time-aware coordinate system.Users can adjust the number of displayed lines and choose dynamic or fixed colors.Source: §7.2 · p. 9
- Orthographic, latitudinal, log-polar, and polar projections provide views for multi-viewpoint maps and visual detection of propagating outer-coronal features.Source: Figure 8 · p. 9, Figure 9 · p. 9
- The field-line appearance was checked against SDO/HMI PFSS extrapolations and the SolarSoft PFSS package.Source: §7.2 · p. 9
8. Timeline functionality
The timeline display combines solar activity proxies and other time-series products with image browsing. Users can inspect timelines and radio spectrograms, synchronize time ranges, and prepare Callisto radio data for display.
8. Timeline functionality
- The timeline was added to display solar activity proxies over long periods and SDO/EVE data alongside SDO/AIA and HMI images.Source: §8 · p. 9
- The canvas displays 1D timelines, 2D radio spectrograms, multiple timelines and y-axes, and event data.The time-handling panel shows the current time position, movie interval, and visible interval.Source: §8 · pp. 9–10
- Available products include Callisto radio spectrograms, GOES XRS data, PROBA-2/LYRA measurements, and SDO/EVE proxies and ESP data.Source: §8 · p. 10
- A timeline adapter translates ODI and STAFF data representations into the JSON format accepted by JHelioviewer.Source: §8 · p. 10
- Callisto files are merged for 24-hour coverage, converted to daily JHelioviewer JPEG 2000 images, calibrated, normalized, and mapped to fixed time and frequency bins.Processing also aims to reduce noise and signal pollution and make events stand out.Source: §8 · p. 10
9. Solar events Integration
JHelioviewer integrates solar events and alerts into a Space Weather Event Knowledgebase, linking event discovery in timelines with inspection of corresponding image series. Users can filter and visually track events.
9. Solar events Integration
- HEK events selected for space-weather relevance and COMESEP alerts are combined in SWEK and shown in image and timeline panels for a chosen period.Users can search event types, such as flares above a specified magnitude, then inspect the corresponding image series.Source: §9 · p. 10
9.1. Event sources
- Events are downloaded in parallel from HEK and COMESEP, cached locally, and the client's last two weeks of cached events are refreshed at startup.Source: §9.1 · p. 10
9.2. Filtering events
- Configurable filters for NOAA SWPC flares and CACTus CMEs include minimum, maximum, and range filters on GOES magnitude and detected radial linear velocity, respectively.Source: §9.2 · p. 10
9.3. Displaying events
- The SWEK layer marks event types with icons, draws available event boundaries, and gives related preceding or following events the same color.Source: §9.3 · p. 10
10. Movie export and annotations
JHelioviewer supports movie export and annotations that remain tied to solar locations over time. Users can also record interactions such as panning and zooming.
10. Movie export and annotations
- Users can highlight solar features with rectangles, circles, or crosses that move in time according to solar latitude, and include them in exported screenshots and movies.Source: §10 · p. 10
- Movies can be exported at different resolutions, and recorded interactions include panning and zooming.The interaction-recording mode may be useful for educational purposes.Source: §10 · p. 10
- The timeline screenshot depicts synchronized time ranges for timeline and image data, alongside the movie and visible intervals.Source: Figure 11 · p. 11
11. Data sources
The Helioviewer Project aims to make diverse solar data available to the worldwide community. The paper also describes ongoing usability work and applications beyond solar physics.
11. Data sources
- The project aims to make as many data sets as possible available to the worldwide community to foster research and exploration of the Sun and inner heliosphere.Data sources include holdings from NASA Goddard, IAS, and ROB servers.Source: §11 · p. 11
12. Improving usability
- Frequent updates, user feedback and bug reports, and automatic performance monitoring are used to improve JHelioviewer’s quality and usability.Source: §12 · p. 11
13. Spin-offs
- Earlier JHelioviewer versions were adapted to visualize HiRISE imagery in planetary science and to support medical histopathology imaging.Source: §13 · p. 11
14. Future work
The paper outlines future work on Solar Orbiter planning and data interoperability, then summarizes JHelioviewer’s expanded capabilities. The software supports browsing solar data and configuring a virtual viewpoint for a spacecraft or celestial body.
14. Future work
- The next phase of development is directed toward the improvements outlined in the paper.Source: §14 · p. 11
14.1. Initiating support for science operations planning of Solar Orbiter
- Solar Orbiter planning motivates extending JHelioviewer beyond photon data to include existing in situ solar-wind plasma measurements.The section also describes event overlays: projected CME propagation appears in the image panel, while event durations appear in the timeline.Source: §14.1 · p. 11, Figure 12 · p. 12
14.2. Improving interoperability and data access
- Future interoperability work will study science-data retrieval through VSO, links to ESA archives, and communication with SunPy and SolarSoft/IDL environments.One implemented approach generates SolarSoft/IDL and SunPy/Python code snippets from user data selections to query and download data.Source: §14.2 · p. 12
15. Conclusions
- The paper identifies the scale and complexity of multi-viewpoint observations and simulation data as requiring new tools for effective use.Source: §15 · p. 12
- JHelioviewer supports visual browsing of time-dependent data from September 1991 onward, with real-time image processing, feature tracking, PFSS overlays, event data, timelines, and a virtual camera model.The camera model sets the vantage point to a spacecraft or celestial body at a given time.Source: §15 · p. 13
- JHelioviewer had been used to create over 1.4 million movies since February 2011, and its architecture and components can be reused in other domains with similar data-volume and browsing constraints.Source: §15 · p. 13