[Paraview] [EXTERNAL] Re: Comparison of Visit and ParaView development

Wed Jun 15 18:55:22 EDT 2016

I use both VisIt and ParaView at NCSA regularly, depending upon what the teams I support are already using. If I have a free hand I generally pick ParaView because (1) I learned VTK first and it’s very straightforward to mentally map a VTK vis pipeline to ParaView and (2) I find the ParaView GUI more intuitive, which is not to be underestimated. Now that VisItBridge is available, I’m even able to get away with mixed projects (though those are rendering projects, not dev projects).

Both scale well in my experience and have for years. I’d like to hear more about what VisIt wasn’t able to scale in the past.

For in situ I have developed with both VisIt’s libsim2 and Catalyst and find Catalyst much easier. With libsim2, it seemed more like that the simulation code had to be shoehorned into VisIt, but maybe that’s been improved since I looked into it.

Both codebases are non-trivial. If you’re planning on developing in the primary codebase as opposed to writing plugins/operators/filters, I don’t think one would be markedly easier than the other.

The python API for ParaView is much more pythonic, IMO.

The downloadable VisIt user manual is for 1.5 and from 2005. Looking at the history in the developer wiki, some of the wiki pages are from 2008, so it’s not clear that its documentation is more up to date.

I don’t mean to bash VisIt, VisIt has some nice features: setting up interactive remote client-server jobs is a snap, the color map editor for volume rendering has easy to use Gaussian opacity transfer functions, you can do some interesting things with queries, etc.

I’ve found both mailing lists to be professional and responsive. I certainly don’t have any complaints about Kitware answering many of the questions, Alan is right, they know more! ☺

From: ParaView [mailto:paraview-bounces at paraview.org] On Behalf Of Scott, W Alan
Sent: Wednesday, June 15, 2016 4:13 PM
To: Geveci, Berk (External Contact) <berk.geveci at kitware.com>; Sven Kramer <svenkramer40 at gmail.com>
Cc: ParaView <paraview at paraview.org>
Subject: Re: [Paraview] [EXTERNAL] Re: Comparison of Visit and ParaView development

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/<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.paraview.org_&d=CwMGaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=lLjWQse1m7sIE-wZm9lCGeCv45WZDxzY072HGbCi4Mg&m=Fk9FzrSbKPDpKCfLSdae3u20A7v10NbTnDTf9cgUpsQ&s=SAAzhkAwLgR023Hbff-s_Nnn2CD4yPAzsHNaxH31AQM&e=>
http://www.paraview.org/paraview-guide/<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.paraview.org_paraview-2Dguide_&d=CwMGaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=lLjWQse1m7sIE-wZm9lCGeCv45WZDxzY072HGbCi4Mg&m=Fk9FzrSbKPDpKCfLSdae3u20A7v10NbTnDTf9cgUpsQ&s=JUMVwWUn5SZRNuzU_LQ18qbosbb-rQFXGETrmg0trTc&e=>
http://www.paraview.org/tutorials/<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.paraview.org_tutorials_&d=CwMGaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=lLjWQse1m7sIE-wZm9lCGeCv45WZDxzY072HGbCi4Mg&m=Fk9FzrSbKPDpKCfLSdae3u20A7v10NbTnDTf9cgUpsQ&s=YBESG2Ue0IRJ6XxOPiFnUO7Vmz5DJkwlALOH4kmmbWA&e=>

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:paraview-bounces at paraview.org] On Behalf Of Berk Geveci
Sent: Wednesday, June 15, 2016 8:18 AM
To: Sven Kramer <svenkramer40 at gmail.com<mailto:svenkramer40 at gmail.com>>
Cc: ParaView <paraview at paraview.org<mailto:paraview at paraview.org>>
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/<https://urldefense.proofpoint.com/v2/url?u=http-3A__m.vtk.org_&d=CwMGaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=lLjWQse1m7sIE-wZm9lCGeCv45WZDxzY072HGbCi4Mg&m=Fk9FzrSbKPDpKCfLSdae3u20A7v10NbTnDTf9cgUpsQ&s=Gt3SCqqRBHKh9_fwCuJDZKzH1EG2_fbPpTYr3Rzpkjk&e=>) 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/<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.tomviz.org_&d=CwMGaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=lLjWQse1m7sIE-wZm9lCGeCv45WZDxzY072HGbCi4Mg&m=Fk9FzrSbKPDpKCfLSdae3u20A7v10NbTnDTf9cgUpsQ&s=3KY60D4eDhxAb0vCc7bq8-6cDRwwyayhk6UFKIezQzE&e=>
* CMB: http://www.computationalmodelbuilder.org/<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.computationalmodelbuilder.org_&d=CwMGaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=lLjWQse1m7sIE-wZm9lCGeCv45WZDxzY072HGbCi4Mg&m=Fk9FzrSbKPDpKCfLSdae3u20A7v10NbTnDTf9cgUpsQ&s=Zg88rgnlu_l7IfCtARJDItW1JqVmL_nTvr-fyfuSlQE&e=>
* VeloView: http://www.paraview.org/veloview/<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.paraview.org_veloview_&d=CwMGaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=lLjWQse1m7sIE-wZm9lCGeCv45WZDxzY072HGbCi4Mg&m=Fk9FzrSbKPDpKCfLSdae3u20A7v10NbTnDTf9cgUpsQ&s=o6h4oemSxG7pY2OW8rP4kR65agxQ9kvd8htsyeRozEA&e=>
* Mantid 3D viewer: http://www.mantidproject.org/<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mantidproject.org_&d=CwMGaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=lLjWQse1m7sIE-wZm9lCGeCv45WZDxzY072HGbCi4Mg&m=Fk9FzrSbKPDpKCfLSdae3u20A7v10NbTnDTf9cgUpsQ&s=dn0S-qxIgeHWGNAndivz8NTZ9ukbiEWlWhlVSqF5D_w&e=>

In addition to a number of commercial cloud based platforms based on ParaViewWeb such as SimScale (https://www.simscale.com/<https://urldefense.proofpoint.com/v2/url?u=https-3A__www.simscale.com_&d=CwMGaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=lLjWQse1m7sIE-wZm9lCGeCv45WZDxzY072HGbCi4Mg&m=Fk9FzrSbKPDpKCfLSdae3u20A7v10NbTnDTf9cgUpsQ&s=3AW8FukzHiAC9Q9ubbOteGC5fRiiFUbmMuwEGueYKz8&e=>). 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/<https://urldefense.proofpoint.com/v2/url?u=http-3A__cinemascience.org_&d=CwMGaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=lLjWQse1m7sIE-wZm9lCGeCv45WZDxzY072HGbCi4Mg&m=Fk9FzrSbKPDpKCfLSdae3u20A7v10NbTnDTf9cgUpsQ&s=tQ1IQkvZg4OA-e-tH9n6SgrrSPZxDOo9BLO51ADVS0M&e=>) 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 <svenkramer40 at gmail.com<mailto:svenkramer40 at gmail.com>> 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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