Move point but keep the mesh (python)

Main question : I would like to know if it is possible to move a point in one direction but keep the mesh in vtk-Python (see image below, with an example of 4 points moved)

I am new to vtk and would like to know if something is possible and if it is, which function to use. (I will give the context under if someone have a more clever idea).

Example

I am using the vtk library with python and came across a pb with the delaunay_2d meshing.
I have a mesh that is mostly flat but with little variation

if you lunch this code, you will see that the meshing is really weird :

import pyvista as pv
import vtk as vtk

a=[[146.2346, -0.06153386, 611.2706],[146.1978, -0.05672521, 611.269],[146.1624, -0.05195256, 611.2675],[146.1345, -0.04595259, 611.2665],[146.0745, -0.02889959, 611.2647],[145.967, -0.01271295, 611.2602],[145.8994, -0.009446936, 611.2567],[145.7876, -0.01544256, 611.2445],[145.6697, -0.02221904, 611.2313],[145.6411, -0.02354358, 611.2281],[145.6213, -0.02429816, 611.226],[145.6148, -0.02446534, 611.2249],[145.6086, -0.02457465, 611.2237],[145.6037, -0.02456888, 611.2228],[145.5997, -0.02445992, 611.2221],[145.5722, -0.02384555, 611.2174],[145.4821, -0.02229311, 611.202],[145.3932, -0.02014619, 611.1866],[145.3392, -0.01758623, 611.1768],[145.2826, -0.01470557, 611.1657],[145.242, -0.01272894, 611.157],[145.2183, -0.01186882, 611.1517],[145.201, -0.01120841, 611.1478],[145.1839, -0.01051717, 611.1439],[145.17, -0.00969123, 611.1407],[145.1583, -0.008427223, 611.1383],[145.1294, -0.007862877, 611.1321],[145.1014, -0.008404535, 611.1261],[145.0899, -0.008730335, 611.1237],[145.0849, -0.008798788, 611.1226],[145.0315, -0.009818145, 611.1109],[144.9335, -0.01140382, 611.0887],[144.8838, -0.01200129, 611.077],[144.8506, -0.0121375, 611.0691],[144.7955, -0.01213034, 611.0557],[144.7571, -0.01195927, 611.0462],[144.7039, -0.0117043, 611.0333],[144.639, -0.01079165, 611.0176],[144.5931, -0.01010639, 611.0062],[144.5228, -0.01040282, 610.9877],[144.4637, -0.01073657, 610.972],[144.4376, -0.01124127, 610.9651],[144.413, -0.01201134, 610.9583],[144.3769, -0.01325327, 610.9479],[144.3213, -0.01482141, 610.9319],[144.2883, -0.01556498, 610.9223],[144.2539, -0.01585945, 610.9122],[144.1733, -0.01677441, 610.8897],[144.1193, -0.01754921, 610.8751],[144.1092, -0.01772558, 610.8723],[144.1012, -0.01783123, 610.8702],[144.0963, -0.01781308, 610.8689],[144.0742, -0.0179998, 610.8631],[144.0339, -0.01839697, 610.853],[143.9804, -0.01873316, 610.8398],[143.9467, -0.01887846, 610.8315],[143.9274, -0.01891992, 610.8267],[143.8417, -0.01886452, 610.8066],[143.7705, -0.01871645, 610.79],[143.7586, -0.01850215, 610.7873],[140.9641, 0.002861298, 575.0103],[140.975, 0.0004340185, 574.9571],[140.9918, -0.004345077, 574.8732],[140.9989, -0.00678831, 574.8369],[141.0005, -0.007331287, 574.8288],[141.0033, -0.00870053, 574.8147],[141.0085, -0.01185749, 574.79],[141.0185, -0.01458415, 574.7529],[141.0268, -0.01585665, 574.7258],[141.0422, -0.02161443, 574.6707],[141.0595, -0.02673956, 574.6101],[141.0743, -0.02733954, 574.5637],[141.0923, -0.02482757, 574.5121],[141.1047, -0.01995062, 574.4816],[141.112, -0.01798161, 574.4629],[141.1168, -0.01754502, 574.4503],[141.1319, -0.01713058, 574.4153],[141.148, -0.01711672, 574.3782],[141.1785, -0.01743222, 574.3112],[141.2074, -0.01777238, 574.2482],[141.2119, -0.01781772, 574.2393],[141.2374, -0.02053488, 574.193],[141.2616, -0.02339841, 574.1488],[141.2682, -0.02405973, 574.1371],[141.2773, -0.02454154, 574.121],[141.2984, -0.0244909, 574.0833],[141.3239, -0.02285809, 574.0379],[141.362, -0.02366696, 573.9743],[141.4008, -0.02681, 573.9104],[141.4111, -0.02758676, 573.8934],[141.4149, -0.02748217, 573.8879],[141.4247, -0.02697612, 573.8746],[141.4432, -0.02813518, 573.8474],[141.4665, -0.03125831, 573.8114],[141.4852, -0.03241773, 573.7831],[141.5292, -0.03128803, 573.7191],[141.5682, -0.03055324, 573.6623],[141.5732, -0.03044086, 573.655],[141.592, -0.02969062, 573.6299],[141.6085, -0.02897164, 573.6082],[141.6247, -0.02817515, 573.5873],[141.6633, -0.02625679, 573.5373],[141.711, -0.0244699, 573.4756],[141.7424, -0.02377839, 573.435],[141.7517, -0.02353401, 573.4231],[141.7648, -0.02296879, 573.4082],[141.7862, -0.02246382, 573.3844],[141.8357, -0.02191633, 573.3298],[141.9018, -0.02097274, 573.2567],[141.9447, -0.02015587, 573.2089],[141.9606, -0.0198681, 573.1911],[141.961, -0.01985728, 573.1907],[141.9736, -0.0194613, 573.1782],[141.9873, -0.01920701, 573.1648],[141.9997, -0.02040373, 573.153],[142.0396, -0.02199398, 573.1149],[142.1073, -0.02463654, 573.0479],[142.176, -0.02768754, 572.9786],[142.2113, -0.02821711, 572.9433],[142.2351, -0.02649652, 572.9198],[142.3082, -0.02100548, 572.8537],[142.3686, -0.01652271, 572.8005],[142.3796, -0.01589324, 572.7906],[142.3981, -0.01486295, 572.7743],[142.4123, -0.01408919, 572.7619],[142.4144, -0.01399181, 572.76],[142.4179, -0.01407487, 572.757],[142.448, -0.01566364, 572.7316],[142.5282, -0.01877348, 572.6642],[142.5982, -0.02105116, 572.6056],[142.6172, -0.02173755, 572.5896],[142.6276, -0.021897, 572.5812],[142.6731, -0.02252371, 572.5445],[142.7521, -0.02395345, 572.4821],[142.8003, -0.02493422, 572.4448],[142.8347, -0.02538628, 572.4179],[142.8763, -0.02544799, 572.3859],[142.9153, -0.02413499, 572.3573],[142.9477, -0.02288336, 572.3338],[142.9768, -0.02149255, 572.3131],[143.0515, -0.01691165, 572.2601],[143.1274, -0.01455436, 572.2069],[143.1697, -0.01542038, 572.178],[143.2005, -0.01505758, 572.1568],[143.2495, -0.01680911, 572.1242],[143.2874, -0.01877392, 572.0992],[143.3077, -0.01987864, 572.0859],[143.3509, -0.02099498, 572.0578],[143.4083, -0.01987314, 572.021],[143.4909, -0.01770812, 571.9689],[143.5684, -0.01706533, 571.9212],[143.5987, -0.01741168, 571.9031],[143.6137, -0.01759005, 571.8942],[143.6689, -0.01668662, 571.8615],[143.7408, -0.01502007, 571.8187],[143.7993, -0.01439461, 571.7853],[143.8609, -0.0165276, 571.7517],[143.8997, -0.01897029, 571.7308],[143.9147, -0.01910335, 571.7229],[143.9507, -0.0185069, 571.704],[144.013, -0.01750005, 571.6713],[144.0648, -0.01632737, 571.6442],[144.0993, -0.01506928, 571.6263],[144.1447, -0.01443901, 571.6029],[144.1923, -0.01450271, 571.579],[144.2355, -0.01467142, 571.558],[144.283, -0.01480775, 571.5352],[144.3439, -0.01599414, 571.5067],[144.4027, -0.01789944, 571.4795],[144.4572, -0.01791742, 571.4552],[144.5246, -0.01659406, 571.4258],[144.5738, -0.01525325, 571.4047],[144.6097, -0.01443211, 571.3898],[144.6464, -0.01424885, 571.3747],[144.6945, -0.01390467, 571.3555],[144.7463, -0.01350234, 571.3347],[144.7808, -0.01354561, 571.3207],[144.8094, -0.01393717, 571.3094],[144.8693, -0.01412922, 571.2871],[144.9426, -0.01378092, 571.2596],[144.9972, -0.01244129, 571.2401],[145.0396, -0.01095316, 571.2258],[145.0826, -0.00853111, 571.211],[145.1198, -0.006981449, 571.1983],[145.1381, -0.009466066, 571.1928],[145.1525, -0.01155278, 571.1885],[145.1717, -0.01150764, 571.1826],[145.1954, -0.01155187, 571.1752],[145.222, -0.01203899, 571.1672],[145.2529, -0.01274025, 571.158],[145.271, -0.01319267, 571.1527],[145.2814, -0.01332585, 571.1496],[145.2997, -0.01334692, 571.1445],[145.3551, -0.01436899, 571.1286],[145.4116, -0.0157692, 571.1123],[145.4388, -0.01593566, 571.1048],[145.4774, -0.0152119, 571.0944],[145.5604, -0.01549523, 571.075],[145.6195, -0.01626525, 571.0623],[145.6802, -0.01707819, 571.0502],[145.7626, -0.01802136, 571.0355],[145.8255, -0.01808286, 571.027],[145.8883, -0.01794028, 571.0183],[145.9254, -0.0178556, 571.0136],[145.9446, -0.017869, 571.0114],[145.984, -0.01818962, 571.0074],[146.0778, -0.01925302, 570.9996],[146.1833, -0.02391875, 570.992],[146.2321, -0.0281701, 570.9886],[146.2426, -0.02938274, 570.9879],[146.2166, -0.05736815, 611.4644],[146.174, -0.05089068, 611.4629],[146.1599, -0.04873756, 611.4623],[146.1137, -0.03929245, 611.4614],[146.0483, -0.02763847, 611.4596],[146.012, -0.02361259, 611.4579],[145.9631, -0.022168, 611.4549],[145.9114, -0.02165178, 611.4517],[145.8622, -0.01918254, 611.4482],[145.8258, -0.01688459, 611.4455],[145.812, -0.01702635, 611.4443],[145.699, -0.02098855, 611.4307],[145.5503, -0.0264029, 611.4119],[145.4873, -0.02732343, 611.4034],[145.4437, -0.02593876, 611.3963],[145.3971, -0.02403616, 611.3883],[145.3718, -0.02247259, 611.3837],[145.3409, -0.02103397, 611.3775],[145.3073, -0.01946996, 611.3708],[145.2901, -0.01852485, 611.3673],[145.1439, -0.01363603, 611.336],[145.0007, -0.008871335, 611.3053],[144.9918, -0.008317093, 611.3033],[144.9818, -0.00827229, 611.3011],[144.9711, -0.008648629, 611.2987],[144.9585, -0.00894847, 611.296],[144.9434, -0.009202947, 611.2927],[144.9355, -0.009293081, 611.291],[144.9336, -0.009293889, 611.2906],[144.9196, -0.009484665, 611.287],[144.8996, -0.009810211, 611.2818],[144.8846, -0.01014345, 611.2779],[144.8513, -0.01053094, 611.2692],[144.807, -0.01110086, 611.2577],[144.726, -0.01263126, 611.2365],[144.6032, -0.01377125, 611.2053],[144.5243, -0.01371456, 611.1859],[144.4985, -0.01368977, 611.1796],[144.4893, -0.01365795, 611.1773],[144.4804, -0.01371251, 611.1751],[144.4578, -0.0137947, 611.1696],[144.4187, -0.01381266, 611.16],[144.3741, -0.01397462, 611.1485],[144.3052, -0.01446937, 611.1297],[144.2563, -0.01481979, 611.1164],[144.255, -0.01484228, 611.116],[144.2525, -0.01495003, 611.1153],[144.2264, -0.01614293, 611.1078],[144.1978, -0.01735986, 611.0995],[144.1808, -0.01762734, 611.0947],[144.1633, -0.01779159, 611.0898],[144.1078, -0.01793095, 611.0743],[144.0449, -0.01793684, 611.057],[143.901, -0.01699888, 611.0205],[143.7598, -0.01609495, 610.9845],[140.8673, 0.004013773, 575.0136],[140.8857, -0.002197082, 574.9198],[140.9067, -0.01009257, 574.8142],[140.9167, -0.01630242, 574.765],[140.9439, -0.02201862, 574.668],[140.9666, -0.02335378, 574.5981],[140.9771, -0.02513118, 574.5642],[140.9885, -0.02729319, 574.527],[140.9966, -0.02716472, 574.502],[141.0051, -0.02627761, 574.4758],[141.0116, -0.02506499, 574.457],[141.0199, -0.02063325, 574.4372],[141.0487, -0.02102182, 574.3722],[141.0777, -0.02478343, 574.3076],[141.0955, -0.02463576, 574.2666],[141.1121, -0.02457507, 574.229],[141.1173, -0.02461446, 574.2178],[141.1236, -0.02464042, 574.2063],[141.135, -0.02530249, 574.1858],[141.1744, -0.02652624, 574.1139],[141.2091, -0.02709656, 574.0502],[141.2377, -0.02136374, 574.0002],[141.2738, -0.01635836, 573.9381],[141.2848, -0.0172927, 573.9203],[141.2951, -0.01758817, 573.9031],[141.3037, -0.01760539, 573.889],[141.3268, -0.01604579, 573.858],[141.3539, -0.01518705, 573.8207],[141.4088, -0.02247747, 573.7359],[141.4684, -0.02852728, 573.6449],[141.4843, -0.02764272, 573.6221],[141.5006, -0.02728717, 573.5983],[141.5111, -0.02722914, 573.5829],[141.5118, -0.02722982, 573.5818],[141.5132, -0.02715779, 573.5799],[141.5294, -0.02634171, 573.5587],[141.5565, -0.02501735, 573.5232],[141.6001, -0.02373889, 573.4655],[141.6579, -0.0224396, 573.3887],[141.6878, -0.0217516, 573.3498],[141.7011, -0.02140111, 573.3354],[141.7217, -0.02115995, 573.3127],[141.7776, -0.020856, 573.25],[141.8334, -0.02046155, 573.1874],[141.8645, -0.01999886, 573.1532],[141.8853, -0.01960157, 573.1304],[141.9001, -0.01918023, 573.114],[141.9348, -0.01900096, 573.08],[141.9562, -0.01924281, 573.0596],[141.993, -0.02112808, 573.022],[142.0713, -0.02525797, 572.941],[142.1216, -0.02746505, 572.8884],[142.1362, -0.02698184, 572.8736],[142.1481, -0.02621646, 572.8619],[142.168, -0.02474578, 572.8435],[142.2107, -0.02196891, 572.8044],[142.2444, -0.01999198, 572.7731],[142.2713, -0.01863434, 572.7483],[142.2985, -0.01733583, 572.7234],[142.3336, -0.01569685, 572.6921],[142.405, -0.01668335, 572.6296],[142.4628, -0.01980776, 572.5797],[142.5035, -0.02117437, 572.5449],[142.5384, -0.02189425, 572.5152],[142.5685, -0.02228352, 572.4902],[142.6137, -0.02278752, 572.4529],[142.6642, -0.02303429, 572.4118],[142.7085, -0.02325433, 572.3763],[142.766, -0.02257066, 572.3312],[142.8821, -0.01881034, 572.2437],[142.9597, -0.01593948, 572.1861],[142.9696, -0.01544765, 572.1788],[143.0172, -0.01338197, 572.1437],[143.076, -0.0114591, 572.101],[143.1149, -0.01234147, 572.0739],[143.1691, -0.01581758, 572.037],[143.2065, -0.01815548, 572.0118],[143.2522, -0.01978064, 571.9809],[143.3011, -0.02127273, 571.948],[143.3377, -0.02081609, 571.9245],[143.4183, -0.01950245, 571.8726],[143.4902, -0.01807297, 571.8264],[143.5343, -0.0175391, 571.7987],[143.5608, -0.01759356, 571.7825],[143.5911, -0.01717058, 571.764],[143.6458, -0.01607553, 571.7306],[143.693, -0.01547654, 571.7024],[143.7485, -0.01548299, 571.6709],[143.8175, -0.01574977, 571.6315],[143.8708, -0.01652237, 571.6017],[143.9491, -0.0160313, 571.5596],[144.0184, -0.01483544, 571.5227],[144.0363, -0.01447774, 571.5131],[144.0637, -0.01432391, 571.4987],[144.1224, -0.01434779, 571.4677],[144.1715, -0.01442718, 571.4422],[144.1953, -0.0145433, 571.4302],[144.2665, -0.01480657, 571.3962],[144.3489, -0.0163923, 571.3569],[144.3814, -0.01844081, 571.3411],[144.4083, -0.01861602, 571.3284],[144.4675, -0.01694035, 571.301],[144.5175, -0.01574981, 571.2781],[144.5462, -0.01568998, 571.2656],[144.5934, -0.01550807, 571.2451],[144.6454, -0.01547175, 571.2229],[144.7203, -0.01478874, 571.1919],[144.7835, -0.01376356, 571.1663],[144.8243, -0.01432241, 571.1497],[144.8731, -0.01529546, 571.1301],[144.8973, -0.01541066, 571.1205],[144.9038, -0.01508989, 571.1182],[144.916, -0.01455041, 571.1138],[144.9556, -0.01379068, 571.1005],[145.0602, -0.01391453, 571.0649],[145.1478, -0.01465114, 571.0349],[145.1655, -0.01478407, 571.0288],[145.1696, -0.0147913, 571.0275],[145.211, -0.01551238, 571.0156],[145.2521, -0.01625661, 571.0038],[145.2546, -0.01630192, 571.0031],[145.2582, -0.01633627, 571.002],[145.2917, -0.01701197, 570.9917],[145.3685, -0.01865086, 570.9682],[145.4243, -0.01943179, 570.9514],[145.45, -0.01889651, 570.9444],[145.4817, -0.01872314, 570.9368],[145.5508, -0.01847148, 570.9219],[145.6074, -0.01799234, 570.9097],[145.6385, -0.01740676, 570.9026],[145.6757, -0.01686226, 570.8941],[145.7179, -0.01731708, 570.8865],[145.7814, -0.01844415, 570.8759],[145.8272, -0.01896315, 570.8686],[145.8773, -0.01869122, 570.8623],[145.9458, -0.01847936, 570.8543],[145.985, -0.01839645, 570.8498],[146.0081, -0.01854843, 570.8472],[146.0541, -0.02106533, 570.8432],[146.1355, -0.02782925, 570.8374],[146.2059, -0.03366203, 570.8322],[146.2263, -0.03505306, 570.8305],[146.2396, -0.03491875, 570.8296]]

cloud = pv.PolyData(tab_point_ds_np)
surf_inter = cloud.delaunay_2d(alpha=0.35)
image = pv.Plotter()
image.add_mesh(surf_inter, show_edges=True)
image.add_points(cloud)
image.add_axes(interactive=True)
image.view_zx()
image.show()

but if i just add that after the generation of ‘a’ to make the point cloud flat, the delaunay_2D work perfectly:

for i in range(len(a)):
    a[i][1] = 0  # Every y at 0

here is the image with and without making it flat :
enter image description here

So my idea was:

  1. generate a flat mesh
  2. move each point on the mesh at the correct altitude

Thanks in advance for your help