[Paraview] Fwd: VTK interpolation help

[Moreland, Kenneth]

I couldn't see the files you posted to dropbox because they were deleted before I got a chance to see them. I also cannot even guess what Star-CCM is doing since I haven't seen that either.

One thing you can try is to apply the loop subdivision filter. That filter subdivides triangles in a polygonal mesh and applies some nonlinear smoothing to the data. To use this filter, first apply the "Extract Surface" filter to your data (to convert it to polygons), and then apply "Loop Subdivision."

-Ken

From: Ruggiero Guida <ruggiero.guida at gmail.com<mailto:ruggiero.guida at gmail.com>>
Date: Saturday, September 27, 2014 at 5:41 AM
To: Kenneth Moreland <kmorel at sandia.gov<mailto:kmorel at sandia.gov>>
Cc: "paraview at paraview.org<mailto:paraview at paraview.org>" <paraview at paraview.org<mailto:paraview at paraview.org>>
Subject: [EXTERNAL] Re: [Paraview] Fwd: VTK interpolation help

Thanks Ken.

Got it. It makes sense. It seems that the only way to improve the quality is to have a finer grid and a more detailed calculation of the amount of radiation (the previous image included only the direct). New images are at this link

https://www.dropbox.com/s/z9m2nr7ybj5mqqp/finermesh.zip?dl=0

I was wondering whether there was a way to at least smooth the results (see other attached image). I have looked at the filters available, but there is no such thing. When I import these results onto StarCCM I definitely see a smoother interpolation.

Thanks
Ruggiero

On 26 September 2014 19:01, Moreland, Kenneth <kmorel at sandia.gov<mailto:kmorel at sandia.gov>> wrote:
Yes, ParaView will use the triangles to interpolate values between points. The interpolation you are getting is exactly as I would expect based on your data and topology. I'm not sure what you mean by "not [interpolating] in the x,y directions". The triangles are in the x-y plane and interpolation is happening in this x-y plane.

Moving into guesswork, I am imagining that you are expecting a smooth  and fairly straight contour at some distance from the buildings. The reason you don't see this is due to the representation in your data. I notice that your data contains only two values for "RadiationOnPerson." The value is either 0 or 205.7. Presumably there is some contour in space where this field discontinuously transitions from 0 to 205.7, but there is no way to accurately predict where that is from the data you are providing. Instead, ParaView is just linearly interpolating between these values, which is wrong but probably the best you can do with the data provided. The problem is made even worse by the irregular sampling of the field.

-Ken

From: Ruggiero Guida <ruggiero.guida at gmail.com<mailto:ruggiero.guida at gmail.com>>
Date: Thursday, September 25, 2014 at 10:44 PM
To: "paraview at paraview.org<mailto:paraview at paraview.org>" <paraview at paraview.org<mailto:paraview at paraview.org>>
Subject: [EXTERNAL] [Paraview] Fwd: VTK interpolation help

Dear group,

I hope I will be able to find an answer to my problem here.

I am not sure I understand how the interpolation works. I have generated a VTK file (attached) and I am trying to visualizing it in Paraview. The data represent the solar radiation on the ground around various buildings.

My algorithm calculates the radiation in each node of a constrained delauney triangulation. The plan is to visualize this in paraview to have a nice smooth fillled contour.

The image I get though, does not make sense to me; it seems that paraview is interpolating only within the triangles and not in the x,y directions. Am I missing something?

Thanks a lot for any help
Ruggiero


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