Re: [Paraview] [Non-DoD Source] Building on Cray systems

and Lightning next. For all of those, I will try the superbuild provided script first to see if it works. Hopefully it does. Tim - Original Message - From: "Andy Bauer" <andy.ba...@kitware.com> To: "tim gallagher" <tim.gallag...@gatech.edu> Cc: "para

Re: [Paraview] [Non-DoD Source] Building on Cray systems

Thanks! If you want to volunteer to rewrite our CMake files, I wouldn't fight you :) I'll let you know when I get it working! Tim - Original Message - From: "Andy Bauer" <andy.ba...@kitware.com> To: "tim gallagher" <tim.gallag...@gatech.edu> Cc: &

Re: [Paraview] [Non-DoD Source] Building on Cray systems

> To: "Chuck Atkins" <chuck.atk...@kitware.com> Cc: "tim gallagher" <tim.gallag...@gatech.edu>, "paraview" <paraview@paraview.org> Sent: Thursday, February 25, 2016 11:21:27 AM Subject: Re: [Paraview] [Non-DoD Source] Building on Cray systems

[Paraview] Periodicity aware streamline?

Hi, I have a simulation that is periodic in 2 of the 3 directions and I would like to plot some streamlines coming from specific points in the domain. Some of these points are close to one of the periodic edges. Is there a way to tell Paraview that the domain is periodic and that streamline

Re: [Paraview] [Non-DoD Source] Building on Cray systems

Sorry if you get this multiple times -- the original was blocked from the PV list because the output log was too big. I can send the log I referred to off-list to anybody who is interested. -- Good morning! Thanks Andy and Richard for the

Re: [Paraview] [Non-DoD Source] Building on Cray systems

- From: "Richard C Angelini (Rick) CIV USARMY RDECOM ARL (US)" <richard.c.angelini@mail.mil> To: "tim gallagher" <tim.gallag...@gatech.edu>, "paraview" <paraview@paraview.org> Sent: Thursday, February 4, 2016 8:54:08 AM Subject: RE: [Non-DoD

Re: [Paraview] [Non-DoD Source] Building on Cray systems

t specific functionality - I can provide you the build scripts we use on those systems. -Original Message- From: ParaView [mailto: paraview-boun...@paraview.org ] On Behalf Of Tim Gallagher Sent: Thursday, February 04, 2016 8:25 AM To: paraview < paraview@paraview.org > Subj

[Paraview] Building on Cray systems

Hi everybody, I'm about to endeavor on the always fun process of building Paraview on Cray systems, specifically Copper (ERDC), Garnet (ERDC) and Excalibur (ARL). Little is ever easy on these systems and I've never succeeded at building paraview on them in the past. However, we want to run

Re: [Paraview] Using Paraview for modeling orbital motion of many objects/database connectivity?

I've also pulled data from a database using a ProgrammableSource and connecting to the database with Python and then building the needed VTK structures from there to pass through the pipeline. I don't know about the built-in ways to use data from SQL, I just did it a brute-force way and got my

Re: [Paraview] Slice not appearing while coprocessing

tu_writer_parameters and proxy=XdmfWriter were found. Is it possible to write out a multiblock dataset from coprocessing using XDMF? Thanks again, Tim - Original Message - From: "Andy Bauer" <andy.ba...@kitware.com> To: "tim gallagher" <tim.gallag...@gatech.e

[Paraview] Slice not appearing while coprocessing

Hi everybody, I was working with a colleague to get his simulation running with coprocessing and I am totally stumped on the problem. I have been able to set up and render some very complex things with our code, but for some reason this simulation just won't work as expected. We generated

Re: [Paraview] Call Python function with parallel reader without pvbatch directly

Andy, I think I've made a mock up of what you are trying to do and may have gotten it to run correctly, if I understood your problem accurately. I have a structure like: package/ driver/ driver.py scripts/ filewithparaviewstuff.py utilities.py The contents of each file are really

Re: [Paraview] Calculate Edge Lengths in Unstructured Grid

0 you will get the minimum for each cell, 1 is the average, etc.. The 5th field (component 4) is used internally and doesn't matter. Hope that helps, Tim - Original Message - From: "Thomas Fastl" <thomas.fa...@kcl.ac.uk> To: "tim gallagher" <tim.gallag...@gat

Re: [Paraview] Calculate Edge Lengths in Unstructured Grid

Thomas, You can use the MeshQuality filter to compute the Edge Ratio for tetrahedral cells. This will give you a field called Quality in your dataset. You can then compute the statistics on it using other filters as needed. That should do what you are looking for. The definitions used in the

Re: [Paraview] Memory overload and I don't know what to delete (despite looking in the archives)

- Original Message - From: "Tim De Coster" <tim91decos...@gmail.com> To: "tim gallagher" <tim.gallag...@gatech.edu> Cc: paraview@paraview.org Sent: Tuesday, January 19, 2016 4:33:49 PM Subject: Re: [Paraview] Memory overload and I don't know what to delete

Re: [Paraview] Memory overload and I don't know what to delete (despite looking in the archives)

Your delete line is Delete(Animationscene1) but your variable is actually called AnimationScene1 (camel-case lettering). Python is case-sensitive, so that's why you are getting the error you are showing. That said, we do two things to loop over everything. We can Delete() every object,

Re: [Paraview] Xdmf format and the contour plot

Apply a CellDataToPointData filter after you load your dataset and before you try to use the contour or stream line filters. They both require node-based data but you are providing cell-centered data. Tim - Original Message - From: "wide li" To:

Re: [Paraview] Velocity field analysis - lambda2

is S_xz, Strain_3 is S_yx... through to Strain_8 = S_zz. With all of those individual components, your Calculator filter for Lambda_2 will just be a bunch of products and sums of those terms. Tim - Original Message - From: "David Larsson" <david.lars...@sth.kth.se

Re: [Paraview] Velocity field analysis - lambda2

David, I haven't taken on lambda-2 yet, but I have been able to build a pipeline for Q-Criterion. It looks something like: Data -> CellDataToPointData (if it isn't already point data) -> ComputeDerivatives (set the gradient option to vorticity and the tensor option to strain) ->

Re: [Paraview] Velocity field analysis - lambda2

For the sake of people years later who come across this thread, there is a typo in my definition and it should be: lambda_2 = S_ik S_kj + \Omega_ik \Omega_kj Tim - Original Message - From: "Tim Gallagher" <tim.gallag...@gatech.edu> To: "David Larsson"

Re: [Paraview] Catalyst: simulation steering during In-Situ visualization

Hi Alexandre, I don't know if this is possible or not with Catalyst, hopefully somebody else comes along to answer that. But, we did this in our code using signal handling and POSIX signals (see http://man7.org/linux/man-pages/man7/signal.7.html). We define 3 behaviors in our code -- reload

Re: [Paraview] Creating a surface along a complex path

;utkarsh.ayac...@kitware.com> To: "Tim Gallagher" <tim.gallag...@gatech.edu> Cc: "ParaView list" <paraview@paraview.org> Sent: Monday, November 23, 2015 10:32:24 AM Subject: Re: [Paraview] Creating a surface along a complex path Is this what you're looking for: ht

[Paraview] Creating a surface along a complex path

Hi, I had an idea I would like to explore but I'm not sure the right way to do it. I have a 3D vtkMultiblockDataset that is composed of curvilinear structured blocks. Let's say I create a line source with s = f(x,y,z). This line source can have a normal vector at each point that is confined to

Re: [Paraview] Saving a slice of data for later visualization

ason for this is that a slice through a multiblock data set outputs a multiblock of polydata. You can use the Merge Blocks filter to reduce it to an unstructured grid. Cheers, Andy On Mon, Oct 26, 2015 at 8:21 PM, Tim Gallagher < tim.gallag...@gatech.edu > wrote: Hi, I'm struggling

[Paraview] Saving a slice of data for later visualization

Hi, I'm struggling to write a script for Paraview that will let me take a slice through my vtkMultiblockDataSet and save just the slice (so all of the data on the slice and all of the points that make up the slice) in a format that I can look at later. I can get it to dump all of the data to a

[Paraview] Converting a graph to a tree

Hi all, I am working on visualization of topological features and I have hit a VTK wall. I have a 2D structured grid that has been built into a vtkMutableDirectedGraph with the vertices as the nodes and the connections between vertices as the edges (not all vertices will end up connected

Re: [Paraview] Converting a graph to a tree

my own questions at the end, the graph nodes need to be stored on the tree by doing: bfs_tree.CreateGraphVertexIdArrayOn() ... graph_ids = tree.GetVertexData().GetArray("GraphVertexId") Tim - Original Message ----- From: "Tim Gallagher" <tim.gallag...@ga

Re: [Paraview] Finding center points/lines of a scalar field

quot;Andy Bauer" <andy.ba...@kitware.com> To: "tim gallagher" <tim.gallag...@gatech.edu> Cc: "ParaView list" <paraview@paraview.org> Sent: Tuesday, October 6, 2015 10:19:01 AM Subject: Re: [Paraview] Finding center points/lines of a scalar field Hi

Re: [Paraview] Import of XDMF/HDF5:Cell centered attribute of 2D Rectangular grid

H5T_IEEE_F64LE DATASPACE SIMPLE { ( 6, 85, 85 ) / ( 6, 85, 85 ) } } } - Original Message - From: Canis Major canismajorw...@gmail.com To: tim gallagher tim.gallag...@gatech.edu Sent: Friday, March 6, 2015 6:05:43 PM Subject: Re: [Paraview] Import of XDMF/HDF5:Cell centered attribute

Re: [Paraview] Import of XDMF/HDF5:Cell centered attribute of 2D Rectangular grid

Hi guys, So the problems you're having are due to specifying inconsistent data here. You are specifying a 2DRectMesh grid but then giving it 3 vectors for the points. I don't have your HDF5 files so I made a light data XMF file that works for me on all versions going back to 3.14. I have

Re: [Paraview] User trying to build with catalyst -- need guidance

Hi Rich, There may be a few who are willing to help out if you can provide some specific questions or issues you run into. Have you looked through the documentation at http://www.paraview.org/in-situ/ ? I got Catalyst up and running in our code (not on a BG/Q but on different clusters) with

Re: [Paraview] ParaView + Catalyst - effort estimation (UNCLASSIFIED)

Hi Simon, I've gone through the process myself and it actually was not that painful, but how long it takes will depend on how familiar you are with VTK already. It's almost trivial if your code's data structures already use VTK. If they don't, then it's a matter of translating your data into

[Paraview] Extracting closed surfaces from an isosurface

Hi all, I am working on a programmable filter and I want to extract and analyze data generated by an isosurface. I'm having a hard time coming up with generic data to represent what I mean, but I'll try to describe it. I run my data and generate an isosurface for a single value. The resulting

Re: [Paraview] Where is the include folder after install?

Are you building it yourself or using a pre-packaged binary? If building yourself, set the PARAVIEW_INSTALL_DEVELOPMENT_FILES option in CMake to ON. Tim - Original Message - From: Daniel WEI lak...@gmail.com To: paraview@paraview.org Sent: Friday, January 25, 2013 2:14:56 PM

Re: [Paraview] HDF5 and Paraview

If you look on the Xdmf Model and Format website (http://www.xdmf.org/index.php/XDMF_Model_and_Format) you can see that there is a 2DCoRectMesh and 3DCoRectMesh topology which can be used to make 2/3D constant spacing meshes with axis aligned to X,Y,Z. And example of how to write this is on

[Paraview] Categorical data in scalar bar

Hi, We have a dataset that ranges from 0 to 7 and represents categorical data. Is it possible through a python script to explicitly set the tick labels on a scalar bar so I can manually map them to strings? For instance: {0.0 - None, 1.0 - I, 2.0 - J,...} Thanks, Tim

Re: [Paraview] CoProcessing needed fields

andy.ba...@kitware.com To: tim gallagher tim.gallag...@gatech.edu Cc: ParaView list paraview@paraview.org Sent: Friday, November 9, 2012 4:21:48 PM Subject: Re: [Paraview] CoProcessing needed fields I can't tell for sure but what are you using as inputName in ParaViewCoProcessor.cxx? It should

Re: [Paraview] CoProcessing needed fields

this little project attempt. I can certainly send my adaptor code and python script if it helps clarify. Thanks again, Tim - Original Message - From: Andy Bauer andy.ba...@kitware.com To: tim gallagher tim.gallag...@gatech.edu Cc: ParaView list paraview@paraview.org Sent: Thursday

Re: [Paraview] CoProcessing needed fields

are in the wrapper C++ code. I may be doing something horribly wrong... But it works when I modified the script as you see in cpScript.py. Thanks, Tim - Original Message - From: Andy Bauer andy.ba...@kitware.com To: tim gallagher tim.gallag...@gatech.edu Cc: ParaView list paraview@paraview.org

Re: [Paraview] Problem building from source

the Module_vtkFiltersExtraction was OFF and INTERNAL until I changed it. Tim - Original Message - From: Tim Gallagher tim.gallag...@gatech.edu To: Utkarsh Ayachit utkarsh.ayac...@kitware.com Cc: ParaView list paraview@paraview.org Sent: Saturday, November 3, 2012 8:15:27 PM Subject: Re: [Paraview] Problem

Re: [Paraview] Problem building from source

file lib/paraview-3.14/libvtkFiltersParallel-pv3.14.so.1 matches So I don't know why I don't have access to it from pvpython. Any ideas what went wrong? Tim - Original Message - From: Utkarsh Ayachit utkarsh.ayac...@kitware.com To: Tim Gallagher tim.gallag...@gatech.edu Cc

Re: [Paraview] Problem building from source

Okay, thanks. I was following the directions at: http://paraview.org/Wiki/CoProcessing which do not mention anything about turning off QT-related things. Thanks, Tim - Original Message - From: Utkarsh Ayachit utkarsh.ayac...@kitware.com To: Tim Gallagher tim.gallag

[Paraview] Problem building from source

Hi, I'm trying to build the code I just pulled on master: git branch * master git describe v3.14.1-2499-g16f07c1 I set VTK_USE_X to OFF: grep USE_X CMakeCache.txt VTK_USE_X:BOOL=OFF but it fails while building with: Linking CXX shared library ../../../lib/libvtkGUISupportQt-pv3.14.so

Re: [Paraview] Can I stop the verbiage that occurs when I start paraview?

If you don't care what it says, you can do: paraview 2 /dev/null which will pipe all output to the void. Tim - Original Message - From: Timothy Cale drtsc.p...@gmail.com To: paraview@paraview.org Sent: Friday, September 7, 2012 3:01:55 PM Subject: [Paraview] Can I stop the

Re: [Paraview] [Xdmf] XDMF Time value problem

We've never had any luck getting time series with XDMF to work correctly in Paraview. However, we create animations all the time. Using the python trace feature, we set up the image using one of the files from the dataset. Then we modify the generated trace file slightly (make it so it's a

[Paraview] Python scripting question in 3.14

Hi, We had a programmable filter that started out like: from paraview import vtk input = self.GetInputDataObject(0, 0) output = self.GetOutputDataObject(0) ngls = 2 if input.IsA(vtkMultiBlockDataSet): nblk = input.GetNumberOfBlocks() print nblk = , nblk for n in range(nblk):

Re: [Paraview] Python scripting question in 3.14

) Grid. Why is the data type returned different now from the vtkMultiBlockDataSet.GetBlock() call? Tim - Original Message - From: Tim Gallagher tim.gallag...@gatech.edu To: ParaView list paraview@paraview.org Sent: Monday, February 27, 2012 2:09:37 PM Subject: [Paraview] Python

[Paraview] Python calculator question

Hi, We're trying to compare two datasets using the Python calculator and the instructions on: http://paraview.org/Wiki/index.php?title=ParaView/Users_Guide/Python_Calculator#Comparing_Multiple_Datasets However, when we choose our datasets and apply the filter, it says it doesn't support

Re: [Paraview] Paraview will not build

I don't really have a horse in the race here, but I've fought a lot with CMake and the old school Makefile/configure setup and CMake is infinitely better. To address your rant: 0. We've used it on every HPC system the DOD, DOE and NASA have to offer with no problems. Cray, IBM, SGI, our own

Re: [Paraview] Scaling up 3-D area in screenshots

The best way to learn what variables/functions to use is to turn on the Python Trace feature in the GUI, change what you want to change, then see what the trace says. In this instance, pull up something to look at, turn on the trace, zoom in, then turn off the trace and it will show you how

Re: [Paraview] Scaling up 3-D area in screenshots

Subject: Re: [Paraview] Scaling up 3-D area in screenshots On 2011-09-22 15:48, Tim Gallagher wrote: The best way to learn what variables/functions to use is to turn on the Python Trace feature in the GUI, change what you want to change, then see what the trace says. In this instance, pull

Re: [Paraview] Python - load state just like when using the GUI

release. Utkarsh On Wed, Aug 24, 2011 at 11:56 PM, Tim Gallagher tim.gallag...@gatech.edu wrote: Hi all, So I did some more digging. It turns out the instructions on the wiki at: http://www.vtk.org/Wiki/ParaView/Python_Scripting#Loading_State_and_Manipulating_It is wrong. If you follow

Re: [Paraview] Python - load state just like when using the GUI

I can make the change to the page (assuming as a new user I can... if not, can somebody update the information?) Tim - Original Message - From: Tim Gallagher tim.gallag...@gatech.edu To: ParaView list paraview@paraview.org Sent: Wednesday, August 17, 2011 11:48:54 PM Subject: Re

Re: [Paraview] Distributing PVSC files (ParaView 4.0)

I know for our HPC access, they require a custom version of SSH that has been security enhanced. So if PV used a built-in libssh, we would be unable to use PV to connect through to them. I don't have a better solution, just wanted to point out that packaging libssh without an option to use a

Re: [Paraview] Python - load state just like when using the GUI

We actually just tried to do the same thing for the first time yesterday and had the same issues... so if anybody has an answer, we'd like it too! Is it just a matter of accessing some kind of data pulled in from the state file and doing a Show() or something? I got the data to appear that way

Re: [Paraview] git update instructions

Or, you can do it in one step (and alias it back to git submodule update, if you would really like to): git submodule update --init This will update all modules and init any that are new. Tim - Original Message - From: David E DeMarle dave.dema...@kitware.com To: David Doria

Re: [Paraview] Programmable filter in parallel

().SetExtentTranslator(self.GetExecutive().GetOutputInformation(0), vtk.vtkExtentTranslator()) David E DeMarle Kitware, Inc. RD Engineer 28 Corporate Drive Clifton Park, NY 12065-8662 Phone: 518-371-3971 x109 On Wed, Aug 3, 2011 at 11:09 AM, Tim Gallagher tim.gallag...@gatech.edu wrote: I guess I sort

[Paraview] Programmable filter in parallel

Hi, I know many of the built-in readers/filters already work in parallel, but how does one write a parallel programmable filter? Our data files are XDMF and split into blocks of data. We have a single XDMF file that we can read that reads all the blocks and generates a vtkMultiBlockDataset

Re: [Paraview] Programmable filter in parallel

, not NCPU MB{}'s. Hopefully that makes sense... I've never used PV in parallel, so I'm not sure how it all works. Tim - Original Message - From: Tim Gallagher tim.gallag...@gatech.edu To: ParaView list paraview@paraview.org Sent: Wednesday, August 3, 2011 9:24:25 AM Subject: [Paraview

Re: [Paraview] Xdmf on master branch

, Tim Gallagher tim.gallag...@gatech.edu wrote: Hi, I just built off the master branch (commit 4f0d9672) and I noticed XDMF_WRAP_PYTHON was no longer an option. It appears it was set to INTERNAL in commit 7ac1f751, which was due to the conversation in the mailing list ( http

[Paraview] Xdmf on master branch

Hi, I just built off the master branch (commit 4f0d9672) and I noticed XDMF_WRAP_PYTHON was no longer an option. It appears it was set to INTERNAL in commit 7ac1f751, which was due to the conversation in the mailing list (http://markmail.org/message/gapnf4reuazdtfcn), although I'm not sure

Re: [Paraview] Cropped screenshots?

The only way I can think is to set the image size and the camera location correctly so you don't have excess space around your data. Image size is set by: RenderView1 = GetRenderView() RenderView1.ViewSize = [1160, 760] And the camera location can be changed by: RenderView1.CameraPosition =

Re: [Paraview] PV 3.10.1 computing vorticity from vector field

and the output will be the same type of field data. I'm about to change this filter so that it will work with all types of VTK grids. Andy On Thu, Jun 2, 2011 at 12:29 PM, Tim Gallagher tim.gallag...@gatech.edu wrote: blockquote The output from the ComputeDerivatives is Cell Data. To do

Re: [Paraview] PV 3.10.1 computing vorticity from vector field

1. If it's cell centered data, apply the CellDataToPointData filter. If it's point data, skip this step 2. Apply the ComputeDerivatives filter. Choose your velocity vector as the Vectors argument, set the Output Vector Type to Vorticity. I usually also set Output Tensor Type to nothing unless

Re: [Paraview] [Xdmf] give a name to a heavy h5 array in a xdmf file

It's quite easy to do in the XMF file: Attribute AttributeType=Scalar Center=Cell Name=H2O_mass_fraction DataItem NumberType=Float Dimensions=36 36 28 Precision=8 Format=HDFoutputpath;/RESTS/REST_N_R00/REST_N_0/REST_N_0.h5:/FlowData/H2O_mass_fraction/DataItem /Attribute for example.

[Paraview] SubSet grid type in Xdmf

Hi, I'm working on an AMR problem and I'm trying to store the grid with Xdmf. In the CGNS file format, there was an OversetHoles node type that defined a list of cells in one grid that should be turned off because another set of cells has that information. I was thinking that the SubSet grid

[Paraview] 3.10 Segfault XDMF

Hi, We're trying to use the 64bit binary of 3.10 to load an XDMF file, but it segfaults as soon as we click on open. Also, I requested this before and somebody replied and said it was done, but the 3.10 release doesn't have it -- Can it be built with XDMF_WRAP_PYTHON turned on? That's the

Re: [Paraview] 3.10 Segfault XDMF

Bummer about XDMF_WRAP_PYTHON, but not a huge deal. The bigger problem is the seg fault when loading XDMF datasets. I'd be happy to give data to replicate the problem if nobody else is seeing the issue. Tim - Original Message - From: Sven Buijssen sven.buijs...@tu-dortmund.de To: Tim

Re: [Paraview] Paraview network interface

It sounds like you want to use Paraview in situ, no? Something like this: http://www.vtk.org/Wiki/CoProcessing Tim - Original Message - From: Alexander Siemers alexander.siem...@skf.com To: paraview@paraview.org Sent: Friday, February 25, 2011 4:01:28 AM Subject: [Paraview]

Re: [Paraview] scripting beginner

Without looking at the script in detail, have you tried using the Python Trace feature in the GUI? Since, at this stage anyway, all of your tasks are straight forward, you can do them in the GUI with the trace turned on, then look at the resulting script to show you how all of it is done.

Re: [Paraview] XDMF and release builds

builds We can probably do this for the final binaries. I was aware that this was off by default. On Fri, Feb 18, 2011 at 9:02 AM, Tim Gallagher tim.gallag...@gatech.edu wrote: Hi, It's probably too late for the binaries already online, and there may be a good reason why it isn't done

Re: [Paraview] unstructured grid, programmable filters: extract, process array data

You can use the Python Calculator, which will let you use any valid Python expression -- such as math.atan2(). Tim - Original Message - From: Nico Schlömer nico.schloe...@gmail.com To: Andy Bauer andy.ba...@kitware.com Cc: paraview@paraview.org Sent: Wednesday, February 16, 2011 8:29:02

Re: [Paraview] unstructured grid, programmable filters: extract, process array data

into a data array. I can't remember the name of it though, perhaps somebody else can help you there if you can't find it online. Tim - Original Message - From: Nico Schlömer nico.schloe...@gmail.com To: Andy Bauer andy.ba...@kitware.com Cc: gtg0...@mail.gatech.edu, tim gallagher tim.gallag

[Paraview] Scripting and new VTK objects

Hi, I've searched online at length for this and couldn't find the answer, so hopefully somebody here can help me. I am trying to create a new VTK object (vtkMultiBlockDataSet) composed of portions of manipulated data from some other VTK object (in this case, a vtkStructuredGrid). I then want

Re: [Paraview] Scripting and new VTK objects

/Python_Programmable_Filter#Generating_Data_.28Programmable_Source.29 http://www.paraview.org/Wiki/Here_are_some_more_examples_of_simple_ParaView_3_python_filters . Pat On Wed, Feb 9, 2011 at 4:20 PM, Tim Gallagher tim.gallag...@gatech.edu wrote: Hi, I've searched online at length

Re: [Paraview] Scripting and new VTK objects

Maybe I'm missing something, but if I from paraview import vtk there is no vtkXDMFReader in it. The only vtkX* is vtkXML related. It was even compiled with XDMF_WRAP_PYTHON turned on, so maybe it's there but called something else? Tim - Original Message - From: Tim Gallagher