I think Berk answered well from a technical and custom applications viewpoint.  
Although not your primary question, I thought I would add just a few words 
regarding ParaView from a user’s perspective.

Here at Sandia National Laboratories, we have seen amazing growth of ParaView 
usage over the last decade.  Last year we had over 330 users.  Last month alone 
we had 161 individual users (not counting support or developers).  ParaView is 
used for projects ranging from toys (learning how to use ParaView with the 
can.exo dataset) to huge (a 100 million cell, 2048 file dataset with 204 
timesteps).  It is being used on everything from interplanetary space probe 
research to visualizing wind turbines to climate change.  Catalyst is also part 
of ParaView development, and Catalyst is making a huge impact here at Sandia.

Regarding documentation, ParaView has come a long way in the last few years 
with regards to user documentation, and I would argue is now similar to 
commercial packages.  Further, the website has all of this information easily 
available.  The next version of ParaView (5.1) features an updated Help menu, 
providing easy access to the ParaView guide, and two full tutorials (the 
Supercomputing tutorial and the Sandia tutorial).
http://www.paraview.org/
http://www.paraview.org/paraview-guide/
http://www.paraview.org/tutorials/

You mention that Kitware appears to be the most active at answering the 
paraview.org list, and this is true.  I believe this is primarily because 
Kitware is by far the most knowledgeable, not because they are the only ones on 
the list.  Thus, you tend to hear from them first.

Regarding your primary question – VisIt vs ParaView, I have no opinions, since 
I don’t know VisIt.

Alan



From: ParaView [mailto:[email protected]] On Behalf Of Berk Geveci
Sent: Wednesday, June 15, 2016 8:18 AM
To: Sven Kramer <[email protected]>
Cc: ParaView <[email protected]>
Subject: [EXTERNAL] Re: [Paraview] Comparison of Visit and ParaView development

I will leave it to the community to address some of these concerns since I am 
obviously biased.

However, Sven made some misguided and unfair statements and I would like to 
address those.

Books: Utkarsh & the ParaView community have put a lot of effort in developing 
a User's Guide for ParaView, which is excellent. This is a community developed 
effort, which is maintained very regularly and is available in print and 
download form in addition to the LaTeX source code. Yes, this is focused on 
users rather than developers but the same would be true for any visualization 
tool out there. In addition, we are in the process of open sourcing both VTK 
books, something which will take some effort because they need to be converted 
from Framemaker to LaTeX. The goal is to combine them in some way and open the 
development to the community. In addition, ParaView will soon leverage VTK-m 
for shared-memory parallel processing (http://m.vtk.org/) and we are developing 
two open source books for that.

Community: First of all, ParaView is a natural extension of VTK. Therefore, a 
lot of development happens at VTK level. I encourage everyone to take a look at 
the archives of the VTK mailing lists including the developer list. You will 
find a very vibrant community that goes well beyond Kitware there. In fact, we 
are a minority on those lists very often. There are well over 50 developers who 
have contributed to VTK over the last few years, from academia, industry and 
government. Almost all algorithmic work is done in VTK. It is true that most of 
the ParaView application is developed by folks at Kitware. Only a few folks 
from the ParaView development team regularly responds to the mailing lists 
(kudos to them). Our team is now 43 people about 20 of whom are focused on VTK 
and ParaView development.

Applications: There are a number of ParaView based applications out there, 
clearly demonstrating ParaView as a viable application platform. Not counting 
VTK based applications because there are too many of those to list here.

* Tomviz: http://www.tomviz.org/
* CMB: http://www.computationalmodelbuilder.org/
* VeloView: http://www.paraview.org/veloview/
* Mantid 3D viewer: http://www.mantidproject.org/

In addition to a number of commercial cloud based platforms based on 
ParaViewWeb such as SimScale (https://www.simscale.com/). Some of these are 
developed at Kitware but some of the have been almost entirely developed 
without very little help from us.

Features: There are a lot of huge features that are making their way into 
ParaView. To be fair, these will also make their way into VisIt because they 
come from VTK so these are really not differentiators between the two. The two 
major ones are the new rendering engine including the use of much more modern 
OpenGL features with huge performance increase and a focus on next generation 
architectures such as GPUs and Xeon Phis though the development of VTK-m. In 
addition, we have a strong focus on in situ analysis through the development of 
Catalyst, which I would argue is the premier in situ library with lots of 
advanced features not available anywhere else. Something we demonstrated 
working very well on 1 million MPI ranks on the Argonne Blue Gene (Mira). Other 
more research focused areas such as Cinema (http://cinemascience.org/) are 
being pushed in VTK/ParaView/Catalyst quite heavily right now. All of these 
focus on exascale computing, which is US Department of Energy push right now.

Issues with ParaView as a development platform:

* It is true that our developer documentation is lacking. ParaView as a 
development platform has never been the main driver so making it more 
accessible to the larger community is something that has not been pushed as 
much as we would like. Not true for VTK though.

* The ParaView code architecture is fairly complicated. This is because it has 
evolved to address the needs of various kinds of applications. A much broader 
set of needs that tools like VisIt tend to focus on. This is because our 
community targets more than HPC Visualization, which were the original drivers 
for both VisIt and ParaView. The kind of applications I listed above is a good 
demonstration of this.

I believe that the main differentiator between ParaView and other vis tools out 
there is the broad functionality _and_ the code quality. Having the two 
together is really tough but our community managed this with a heavy emphasis 
on code review and code testing. I strongly recommend that folks look at the 
software processes used to develop VTK & ParaView as well as the huge amount of 
testing (both test quantity and platform coverage) that we do before every 
single commit in addition to nightly. There is a very good overlap between the 
CMake, CTest & CDash communities and the VTK/ParaView development communities 
and there is very good reason behind this.

Best,
-berk


On Wed, Jun 15, 2016 at 6:54 AM, Sven Kramer 
<[email protected]<mailto:[email protected]>> wrote:
Dear ParaView programmers,
I would like to have some opinions on the suitability of either ParaView or 
Visit for large scalable visualization applications. When I had the first 
contact to visualization more than 5 years ago, Visit was not quite scalable 
and ParaView seemed the only open source alternative.
Now I am trying to get into some serious developments, and although most papers 
in the field still cite ParaView as their development framework, there seems to 
be no active developers community except for two or three kitware employees. 
Questions on this list are at the most basic level, and nobody seems to be able 
to answer, who isn't working for kitware.
My impression is that ParaView has grown so complicated over the years that it 
is no longer usable as a framework for parallel visualization development. Only 
the ParaView application itself is still frequently used.
On the other hand, Visit seems to have overtaken ParaView in all aspects. Most 
important is the high quality documentation and very active community, 
scalability is now as good as ParaView, and collaborative web visualization is 
coming rapidly.
What is your opinion? Are there any points, where ParaView is clearly 
advantageous over Visit? Or is it used by most people only out of convenience, 
because they have always worked with ParaView?
Given the horribly out of date books on ParaView and parallel VTK development, 
web documentation mixing three major versions without stating which version is 
referred to, and the dead development discussions I don't see any possibility 
of learning ParaView programming today. Which material do you use for tutorials 
and documentation?
Thank you
Sven

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