Actually, I agree and disagree. But I'll definitely agree with your
implied point to understand your requirements well and find the tool(s)
that best address them.
IDL is designed to deal with simple data (i.e., regular arrays) independent
of dimensionality. So its operations and interfaces are focused on that,
and it supports them well. This not is not an architectural issue with DX,
it's just that more tools along these lines have been implemented in IDL
than in DX. For example, when I built some applications with remote
sensing data using both DX and IDL long ago, it was sort of silly to
duplicate in DX what IDL already had, although it could be done. Although,
I do find it's actually easier to build up higher-level functionality in DX
rather than IDL with visual programming. I do the sort of things you imply
with DX pretty easily. On the other hand, I have been using DX for a
while...
However, the strength of IDL is the high-level language. It's more
complete from a programming perspective than the DX scripting language but
much more primitive from the data perspectives (i.e., IDL's variables are
only simple arrays at most). IDL doesn't handle non-regular data, even 2d,
very well or even correctly, although it gives the appearance of doing so
(e.g., curvilinear grids, triangular meshes). DX is better in that regard.
However, if you never deal with such data, than such an advantage means
little. Thus, a less general tool but one focused on your problems is a
better choice.
You can add functions to DX or have your software invoke DX. There's been
some discussions on that in the DX mailgroups and there's a lot of
documentation about that. In earlier releases of IDL, this was always
pretty limited (i.e., a problem when we had an IDL<->DX interface). I
understand that newer versions of IDL are much better in this regard, but
I've not used them.
The issue with output again could be more completely addressed in DX, but
it was either a lower priority or duplicated things done in other packages.
But there is more there than is apparent at first glance in DX but not as
much as IDL has. Actually the support for such things in IDL is historical
since one of the basic display types was vector-based for supporting pen
plotters, which was migrated to Postscript years ago from things like
HP-GL.
Open vs. proprietary (bazaar vs. cathedral) is of course a subject of wide
debate, so I won't talk about the relative advantages and disadvantages of
each...
Thanks for your comments.
---------------------------------------
To: [email protected]
Subject: Re: [opendx-general] general question to OpenDX; comparison
with IDL
From: "Sharon Cady" <[EMAIL PROTECTED]>
Date: Tue, 14 Mar 2000 13:36:52 -0500
In-Reply-To: Johannes-Maria Kaltenbach <[EMAIL PROTECTED]>
"[opendx-general] general question to
OpenDX; comparison with IDL" (Mar 13, 6:40am)
References: <[EMAIL PROTECTED]>
Reply-To: [email protected]
Sender: [EMAIL PROTECTED]
I've also used both IDL and DX at a moderately high level. However, in my
work
I've never had the necessity to utilize much of the functionality that
might
contribute to DX ranking superior to IDL.
Lloyd made a lot of good points, but in my opinion it all boils down to
whether
or not you need to do any 3-d or "classical" visualizations. For this, DX
wins
hands down. But for standard array imaging operations, it is sort of
senseless
to use DX. All that extra capability sort of weighs you down. In this
regard,
IDL is very simple to use.
I've found DX to be a bit cumbersome for repetitive processes as well -
such as
for displaying and comparing several highly processed images at once. There
are
methods for doing looping in DX, and for organizing things in groups, but
IDL
is again less complex.
In the type of work that I do at least (remote sensing imaging) an
externally
linked "C" or other language program would be required to accomplish
certain
tasks more often in DX than in IDL. I'd be interested to hear about other
people's experiences on this.
IDL is also much more flexible with regard to hard copy output. DX doesn't
always allow you to make things look exactly how you want them to, in terms
of
fonts, positioning, etc.
I'm not a computer system person, so I can't tell you much about the
advantages/differences in that regard, but I can say that from the amount
of
traffic that goes through this news group, there are plenty of installation
difficulties that people run into with OpenDx. Plus, the "Open" part of
OpenDX
is fairly new, and I get the impression that there are still a few kinks to
work out. You might want to keep that in mind if you or your company is
already
familiar with IDL, but know nothing about DX.
