[vtkusers] VTK class to do interpolation of scalar values

Mon Dec 7 13:55:20 EST 2009

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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