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de Coussemaker, N. 2000, in ASP Conf. Ser., Vol. 216, Astronomical Data
Analysis Software and Systems IX, eds. N. Manset, C. Veillet, D. Crabtree (San Francisco: ASP), 479
Panorapix - The TERAPIX Visualization Tool
N. de Coussemaker
Institut d'Astrophysique de Paris, 98 bis bd Arago, F75014 Paris
Abstract:
Panorapix is a new X11 client for visualizing FITS images on UNIX
platforms, developed in the context of the TERAPIX project.
The code is in C++ and uses the Qt library which provides an
ergonomic look-and-feel to the interface. Huge images (32k
32k
pixels and even bigger) can be comfortably visualized even on a modest
machine. Up to twelve files can be dealt with simultaneously and
all kinds of X display are supported (8, 16, 24 and 32
bits-per-pixel).
In the very first version, the most important tools have been
implemented (zooming, panning, coordinates, intensity, ...), but new
functionalities will easily be added.
The MEGACAM instrument, mounted on the CFHT, will produce
18k18k images. The TERAPIX center, in charge of processing the
MEGACAM data, will routinely deal with even larger composite
images. As existing astronomical software was not able to display
those huge images in an efficient way, a new visualization tool has
been developed.
Panorapix, in its very first version, provides the most important tools
(zooming, panning, coordinates, intensity, ...). To these basic
tools, we have added the possibility to move the image smoothly with a
``hand'', to calibrate the monitor and to manipulate the color maps by
using cubic-splines.
Panorapix's salient features are:
- Portability,
- Object oriented (C++), modular code,
- Ergonomic feel (Qt library),
- Runs on all UNIX platforms,
- Accepts images of any size,
- Fast access to any part of huge images,
- Free access to the full dynamic range of data,
- Optimized for true color displays,
- Optimized for slow client/server connections,
- ``Intelligent'' blink (with up to 12 images).
Many programs are limited by the physical memory of the machine they
use. To solve this problem, we decided to use memory mapping.
With this mechanism, the image file becomes a part of the process data
segment and the OS handles all page swapping. The main advantage of
this method is that no input/output functions (read, write, seek) are
used so one can rapidly access any part of any image.
Tests have been done on two different machines and the results are
presented in Figure 1 and Figure 2:
- XP1000 - 500MHz - 2GB RAM - RAID 5
- PII - 450MHz - 512MB RAM - SCSI 3
Figure 1:
Maximum loading time.
|
Figure 2:
Maximum time to move from end to end.
|
Panorapix has permanent access to the full data dynamic range. In
contrast to other program, it does not use a temporary buffer prior to
image display: the exact data value of each pixel is converted to its
screen value in real time.
More informations and demonstration are available on TERAPIX web site:
http://terapix.iap.fr/panorapix.
© Copyright 2000 Astronomical Society of the Pacific, 390 Ashton Avenue, San Francisco, California 94112, USA
Next: New Image Quick-Look System for Subaru Telescope Data Archive
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adass@cfht.hawaii.edu