[vtkusers] VTK class to do interpolation of scalar values

Mon Dec 7 14:11:26 EST 2009

Jesse,

I loaded your data into paraview (paraview.org), applied the
Delaunay2D filter->ContourFilter and produced the attached image. Is
this what you would expect?

Bill

On Mon, Dec 7, 2009 at 1:55 PM, Jesse Kim <jinryongkim at gmail.com> wrote:
> Hi Bill and David,
>
> Thanks for the reply.
> For the clarification, let me provide my sample data set. What I would like
> to do here is to do the interpolations among these scalar values associated
> with some geographical locations (75 locations) so that I can have smooth
> iso-contour or iso-surface. This the dataset of some geographical locations
> (75 locations) and their scalar values.
>
> # vtk DataFile Version 2.0
> Weather observing stations
> ASCII
> DATASET POLYDATA
> POINTS 75 float
> 660.905194 527.736720 0.0
> 536.263098 683.230547 0.0
> 702.452710 1112.016367 0.0
> 710.006701 838.724374 0.0
> 354.965505 414.650300 0.0
> 660.905194 862.283951 0.0
> 694.898493 485.329312 0.0
> 657.128312 612.551535 0.0
> 589.141714 975.370370 0.0
> 490.938700 424.074074 0.0
> 260.539826 640.823140 0.0
> 317.195324 805.740741 0.0
> 260.539826 376.954638 0.0
> 366.296604 164.917601 0.0
> 113.235531 75.391041 0.0
> 128.343513 98.950617 0.0
> 664.682303 720.925926 0.0
> 653.351203 932.962963 0.0
> 358.742613 735.061728 0.0
> 173.667911 329.835485 0.0
> 158.559929 1107.3046210 0.0
> 498.492917 1088.4567900 0.0
> 294.533125 546.584268 0.0
> 524.931999 588.991675 0.0
> 589.141714 466.481481 0.0
> 524.931999 245.020670 0.0
> 181.222129 1088.4567900 0.0
> 256.762717 160.205856 0.0
> 585.364606 890.555556 0.0
> 407.844121 574.855873 0.0
> 528.709108 164.917601 0.0
> 430.506320 782.181164 0.0
> 385.181921 862.283951 0.0
> 608.026805 292.139823 0.0
> 547.594198 815.164515 0.0
> 370.073713 480.617284 0.0
> 298.310007 862.283951 0.0
> 41.471825 65.966984 0.0
> 604.249696 711.502152 0.0
> 162.336811 65.966984 0.0
> 460.722510 669.094744 0.0
> 562.702406 367.530864 0.0
> 347.411514 334.547231 0.0
> 362.519722 240.308642 0.0
> 132.120621 669.094744 0.0
> 177.445020 226.172840 0.0
> 396.513021 1027.2015520 0.0
> 67.911133 131.934251 0.0
> 113.235531 183.765432 0.0
> 211.438319 914.115132 0.0
> 725.114910 617.263280 0.0
> 422.952102 951.810794 0.0
> 192.553228 584.279930 0.0
> 596.695705 537.160494 0.0
> 728.891792 758.621305 0.0
> 453.168519 259.156473 0.0
> 521.155117 278.004021 0.0
> 475.830718 362.818836 0.0
> 517.378008 518.312663 0.0
> 290.756016 273.292275 0.0
> 396.513021 1130.864198 0.0
> 298.310007 70.679012 0.0
> 154.782821 499.465115 0.0
> 237.877627 1079.033016 0.0
> 679.790511 296.851852 0.0
> 135.897730 292.139823 0.0
> 513.600899 871.707725 0.0
> 502.269800 998.929947 0.0
> 215.215427 259.156473 0.0
> 260.539826 768.045362 0.0
> 245.431617 786.892910 0.0
> 218.992309 989.506173 0.0
> 392.735912 650.246914 0.0
> 324.749315 310.987654 0.0
> 339.857523 942.386737 0.0
> POINT_DATA 75
> SCALARS req_prep_0 float
> LOOKUP_TABLE default
> 184.949631
> 125.071189
> 114.655333
> 142.508891
> 250.255094
> 132.980147
> 132.369983
> 104.52796
> 331.737495
> 336.049583
> 214.249765
> 117.033152
> 329.449907
> 266.396892
> 147.324093
> 293.163118
> 104.33426
> 313.719804
> 207.564979
> 109.947172
> 143.08005
> 143.859373
> 189.977409
> 126.483623
> 217.989847
> 372.728658
> 343.744282
> 94.816421
> 187.774541
> 186.499795
> 337.102472
> 182.862572
> 125.000005
> 520.225266
> 267.150263
> 104.699336
> 187.176938
> 111.811702
> 314.11783
> 463.261076
> 131.671659
> 361.803069
> 272.000024
> 178.927209
> 274.940403
> 176.914528
> 249.996726
> 225.34729
> 220.164636
> 192.443055
> 274.59666
> 242.720081
> 163.316313
> 214.000012
> 150.596283
> 274.416211
> 532.135911
> 453.662097
> 229.363398
> 733.273974
> 151.398179
> 162.908337
> 244.352757
> 332.847796
> 480.445379
> 541.82268
> 384.111595
> 201.312356
> 234.118599
> 185.278497
> 159.692496
> 281.602642
> 356.659038
> 377.949511
> 469.000015
>
> Bill Lorensen wrote:
>>
>> The data for the example should be some points scattered in space. I
>> assume that is what Jin has, not just three points on a line. I'll dig
>> up some meaningful data, uless Jin can share a small sample of his
>> data.
>>
>> Bill
>>
>> Bill
>>
>> On Mon, Dec 7, 2009 at 1:11 PM, David Doria <daviddoria+vtk at gmail.com>
>> wrote:
>>
>>>
>>> On Mon, Dec 7, 2009 at 12:20 PM, David Gobbi <david.gobbi at gmail.com>
>>> wrote:
>>>
>>>>
>>>> On Mon, Dec 7, 2009 at 9:51 AM, David Doria <daviddoria+vtk at gmail.com>
>>>> wrote:
>>>>
>>>>>
>>>>> On Mon, Dec 7, 2009 at 11:43 AM, Jin Ryong Kim <jinryongkim at gmail.com>
>>>>> wrote:
>>>>>
>>>>>>
>>>>>> I have a question about interpolation method in VTK.
>>>>>> Currently, I'm trying to interpolate scalar values between data points
>>>>>> to
>>>>>> create a contour map.
>>>>>> I have some data points set (x, y, z) and scalar values related with
>>>>>> each
>>>>>> data point.
>>>>>> So far, I found out vtkProbeFilter but when I tried, nothing came up.
>>>>>> My questions are as follow.
>>>>>> 1. Is vtkProbeFilter the right choice in this case?
>>>>>> 2. If not, what are the right vtk classes to accomplish such a goal?
>>>>>> If anyone has the solution for this, please let me know.
>>>>>> Thanks in advance!
>>>>>>
>>>>>
>>>>> Jin,
>>>>>
>>>>> If I'm not mistaken you sent this same question yesterday. I am
>>>>> interesting in making an example of this so I have started poking
>>>>> around. I understand that you may be in a hurry, but asking twice is
>>>>> just going to annoy people on the list, making your answer come
>>>>> slower, not faster.
>>>>>
>>>>> Can anyone confirm or deny that ProbeFilter is the right way to go?
>>>>>
>>>>
>>>> The probe needs cells to interpolate the data.  If all you have is
>>>> points, then you have to apply delaunay first to make the cells, and
>>>> then use probe to interpolate the data onto a grid (i.e. make an
>>>> image), and then contour the grid.  It might also be possible to
>>>> contour directly from the output of delaunay, but I'm not sure whether
>>>> VTK can do that.  I'm no expert in this area, but hopefully I've
>>>> answered your question.
>>>>
>>>>  David
>>>>
>>>>
>>>
>>> From Bill's suggestion I have tried to make an example:
>>> http://www.vtk.org/Wiki/VTK_Examples_Interpolation
>>>
>>> the problem is that the Shepard filter outputs an ImageData and the
>>> ContourFilter seems to expect a DataObject.
>>>
>>> Jin, this is a simple version of what you are trying to do, correct?
>>> If so, let try to get this little demo working.
>>>
>>> Thanks,
>>>
>>> David
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>>
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>
>
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