however, as scatteredInterpolant requires at least 2 dimensions for its indices, this doesn't work for 1d interpolation. Create a PDE model and include the geometry of the built-in function squareg. This mesh is equivalent to the bounding box for Alaska. You can evaluate F at a set of query points, such as (xq,yq) in 2-D, to produce interpolated values vq = F (xq,yq). 9. pwl_interp_2d_scattered , a C++ code which produces a piecewise linear interpolant to 2D scattered data, that is, data that is not guaranteed to lie on a regular grid. I've written a code that uses TriScatteredInterp, but I read in Matlab's documentation that this will not be supported in future release and that I should instead use scatteredInterpolant. Learn more about interpolation, griddata, scatteredinterpolant Hello, I have a quite large dataset of about 57 million uniformly gridded density samples in 3D space (four column vectors x, y, z and d of length 5. Parameters. My first attempt to solve this was the interpolation methods in MATLAB. 912 etc etc. This is a shape-preserving spline with continuous first derivative. Inputs x, y, z are vectors of the same length or x, y are vectors and z is. griddata# scipy. MATLAB is a high-performance language developed by MathWorks for technical computing, visualization, and programming. 网格和散点数据插值、数据网格化、分段多项式. Create one surface from each scatteredinterpolant, using nans for values which are on the other side of the discontinuity. I am able to calculate the Delaunay tetrahedrals using the TetGen library. Interpolation is a technique for adding new data points within a range of a set of known data points. The function is defined by z = f (x, y). You can evaluate F at a set of query points, such as (xq,yq) in 2-D, to produce interpolated values vq = F (xq,yq). Below is a plot of the original (uninterpolated) data with shading interp turned on using "surf" and "trisurf" plotting. In this case will be F = scatteredInterpolant (x,y,v), which the function itself is trying to get the F in v = F(x,y). On the other hand, you indicate that you want to be able. [x,y] = ndgrid (0:10,0:5); Create two different sets of sample values at the sample points and concatenate them as pages in a 3-D array. 01 -160. F = scatteredInterpolant (x_c,y_c,z_c); Walter Roberson on 9 Dec 2015. scatteredInterpolant returns the interpolant F for the given data set. I tried to put the. Values for reinterpolating on the same coordinates. thanks for you reply @image. interpolate. Xq, Yq, and Zq contain. また、R2013a 以降では、グリッドデータに対しては griddedInterpolant 関数, 散布データに対しては、scatteredInterpolant 関数を使用することができます。. 01,0. Overview of the ALGLIB RBF's. % Section Classification Flange width to thickness ratio in compression. I was able to improve the efficiency of the processing in RGB images using the "parallel computing toolbox" (number of workers: 4, in my i5 CPU) and reutilizing the same interpolant for the 3 channels. It is a quick and simple fix, but I recommend. scatteredInterpolant proporciona una funcionalidad para aproximar valores en puntos que se encuentran fuera de la envolvente convexa. scatteredInterpolant returns the interpolant F for the given data set. Parameters: pointsndarray of floats, shape (npoints, ndims); or Delaunay. Use scatteredInterpolant instead. m and the testPerfo2. 000 417826. 25; 3. Show 2 older comments Hide 2 older comments. How to retain duplicate while using. Use griddedInterpolant to perform interpolation with gridded data. scatteredInterpolant returns the interpolant F for the given data set. Take the output of the "scatteredInterpolant" and put it through an if statement that checks if it is within the boundary. I have a second question regarding this process, which I will not ask here, but I was wondering if this process itself can be done in parallel processing because it takes VERY long for decently high resolutions. Interpolant surface fits use the MATLAB ® function scatteredInterpolant function for none, linear, and nearest neighbor extrapolation, and the MATLAB function griddata for biharmonic extrapolation. You can evaluate F at a set of query points, such as (xq,yq) in 2-D, to produce interpolated values vq = F (xq,yq). My question is : can we speed up the scatteredinterpolant function by using it with parallel too. I want then to use those to create an interpolant where I can send new x,y values and get a z-value back. scatteredInterpolant returns the interpolant F for the given data set. It is just presented as being v = F(x,y) because effectively that is what it is. txt') x = Point_Cloud (1,:)'; y = Point_Cloud (2,:)'; z. The first output FX is always the gradient along the 2nd dimension of F, going across columns. scatteredInterpolant is used to perform interpolation on a scattered dataset, which is basically what you have. I recently had the need to create a smoothed curve from a series of X/Y data points in a C# application. 128 1682. Suppress Warnings. The function in matlab is called Tri=delauny (X,Y,Z). Others have suggested extrapolation. . x = sort (20*rand (100,1)); v = besselj (0,x); Create a gridded interpolant object for the data. If you believe scatteredInterpolant is computing the wrong answer but cannot share the data with the community, please send your call to scatteredInterpolant along with the data necessary to execute that call and a description of why you believe its answer is incorrect (such as the results from a different interpolation routine) to Technical. 1. El método de extrapolación 'linear' se basa en una aproximación por mínimos cuadrados del gradiente en el límite de la envolvente. Unfortunately MATLAB does not have any scattered interpolation routines that work in more than 3 dimensions, but gridded interpolation can. Perl. @rahnema1 the absolute positions and corresponding data will not change, regardless of whether you're in Cartesian or in Polar coordinates. Prototyping at the command line may not yield the same level of performance. You should have a look whether your ellipse is matching the used grid for plotting. . I have created an interpolant "F", using the function "scatteredInterpolant". scatteredInterpolant had to be used. InterpolatePchipSorted instead, which is more efficient. The subject line could equally well cite scatteredInterpolant as it shares the same underlying code as griddata. What I have is a bunch of points (x,y,w), where x and y are coordinates and w is the value. I have tried num = 1,3,4, and as you suggest in your notes 3 is best, but, by eye, still exaggerates the missing corner points. Description. xlsx) file. interp2 performs many checks before calling griddedInterpolant, which is the reason for its ~400ms slower performance. Theme. It is written in C, C++, Java and. It also looks like my interpolant to a regular grid isn't working?Hello, I am currently doing EEG traceability research, because I only have the subject’s EEG data and no MRI data, so I used the MRI template. It also provides good (though not perfect) continuity for slope. Scattered data, with some nasty stuff to interpolate on the edges, but still what appears to be a single valued relationship. Walter Roberson on 9 Dec 2015. That the HDF investigation revealed no stored data structure confirms suspicions raised by timing of loading the data. It allows Natural neighbour interpolation (that is a class of weighted distance interpolation as suggested in previous comments). You CANNOT use interpolation with three independent variables, when one of them is IDENTICALLY zero. Following is the code that I used in my, You can tailor it according to your needs: vel. You can evaluate F at a set of query points, such as (xq,yq) in 2-D, to produce interpolated values vq = F (xq,yq). I have following type of data. I want to specify that scatteredInterpolant worked well in a script but not in the simulink function block My scattered model data are 3 . Accepted Answer: KSSV. The support engineers are great, they really know how to choose a good subject line that will get a developer's attention and get a response back to the customer quickly. The griddata function interpolates the surface at the query points specified by (xq,yq) and returns the interpolated values, vq. Then I can query the interpolated values by supplying a set of positions: F = scatteredInterpolant(xpos, ypos, samplevals) interpvals = F(xgrid, ygrid) This is sort of the opposite of what I want. I am doing data interpolation using scatteredinterpolant method. We also interpolate between multiple solutions, which leads to even higher. 9. When you call scatteredInterpolant on the resulting matrix, it will still average the duplicates, but they will all have the same value. This means your matlab version has sample points at the positions U,V. I'm sorry, but you simply cannot use scatteredInterpolant to produce a meaningful result from this data, as you are trying to do. I would like to make a contour plot. Keep in mind that gridded data must include all data points on the grid: as. Selecting an Extrapolation Methodclass scipy. " Does this mean that the function discovered duplicate (x,y) grid points in my inputs, or that some adjacent z-points are duplicated?scatteredInterpolant supports (x, y, v, then options, or (x, y, z, v, then options, so building an interpolation object over 2d or over 3d, that you then invoke with the appropriate number of input parameters to get results. Learn more about interpolation, matlab function, grid, gridded data, grid data, griddedinterpolant, scatteredinterpolant, interp2, interp, fine resolution data, fine data, large data MATLAB Online ServerTo plot the data, I use scatteredInterpolant, then create a meshgrid of the interpolated data. That is, a given sample point (x,y) must correspond to a unique value z. How to use scatteredInterpolant in case of. 125) ans = 0. Hello, I want to call the value F_a(Mach,he) with Simulink. I process the data:scatteredInterpolant Scattered data interpolation scatteredInterpolant performs interpolation on scattered data that resides in 2-D or 3-D space. New in version 0. Updated on Apr 21, 2022. However, it is even slower than the inpaintn function mentioned by Walter. If it is possible in your situation that the function as sampled is not uniformly surrounded by constant values smaller than the next closest interior points, then there could be an angle where the exterior points could be considered to have an upwards slope. griddedInterpolant returns the interpolant F for the given data set. Scipy provides a lot of useful functions which allows for mathematical. More Answers (1) If your data are in a rectangular grid (i. From MatLab documentation: ZI = interp2(X,Y,Z,XI,YI) returns matrix ZI containing elements corresponding to the elements of XI and YI and determined by interpolation within the two-dimensional function specified by matrices X, Y, and Z. scatteredInterpolant works perfectly with the syntax I used above, so thank you for this. However, I do not understand exactly what happens if some of the. LinearNDInterpolator(points, values, fill_value=np. Teams. Más respuestas (1) In some cases you can have a set of x and y data where the values of x and/or y are repeated as Aristo was showing. "scatteredInterpolant(P_ent_mod,D_ent_mod,E_s_mod)" Launch diagnostic report. 2-D array of data point coordinates, or a precomputed Delaunay triangulation. scatteredInterpolant() on the. Besides splitting the creation of the object from the invocation for interpolation purposes, griddata simply does not. . A scattered data set defined by locations X and corresponding values V can be interpolated using a Delaunay triangulation of X. followed by using ScatteredInterpolation to load the package. x,y and v are vector (1x77), while xip and yip are sample points (1x51 and 1x21)Using the scatteredInterpolant class I was able to get velocity at any location I want. Parameters: points 2-D ndarray of floats with shape (n, D), or length D tuple of 1-D ndarrays with shape (n,). My scattered data (sample: XS1 and XS2) have [x,y,z] values and appear as multiple lines. 25; 3. The plot is formed by joining adjacent points with straight lines. griddata -- always x, y, v (scattered 2d input coordinates plus corresponding outputs). Sub-package for objects used in interpolation. Evaluate the interpolant at the query points with the syntax F ( {xq,yq}). La interpolación en MATLAB ® se divide en técnicas para puntos. v in the ScatteredInterpolant is just your data values at the x and y locations. I have two data sets of different sizes, one of which is a 15x3 matrix of latitude, longitude, and concentration data and the other of which is a 2550x3 matrix, also composed of latitude, longitude, and concentration data. >> F = scatteredInterpolant(xdata, ydata, vals, 'natural' , 'none' );scatteredInterpolant allows me to provide a set of input sampling positions and the corresponding sample values. According to the docs scatteredInterpolant(x,y,v) takes x, y as points and v as surface data to interpolate. scatteredinterpolant will ALWAYS reproduce the data exactly, although it may sometimes introduce tiny noise on the order of eps, just due to floating point arithmetic. scipy. See the above example with nine points that represent four axis-parrallel elements. Syntax: VI = scatteredInterpn(X. In the for-loop for ever. interpolate. There is no cylinder. I have a geographically distributed data set with X-coordinate, Y-coordinate and corresponding target value of interest D. 2. Interpolation (. scatteredInterpolant returns the interpolant F for the given data set. Thus, since scatteredInterpolant will only provide at best a piecewise linear surface, you may want to use a tool like griddata or my own gridfit. A scattered data set is defined by sample points X and corresponding values v. 6 3. A scattered data set defined by locations X and corresponding values V can be interpolated using a Delaunay triangulation of X. interpolate. The query points lie on a planar grid that is completely outside domain. Ideally the interpolation object. Theme. The goal is to create gridded data from scattered data. To use griddedinterpolant or interp2, a meshgrid or ndgrid needs to be created using lat, lon values. Copy. random(100) # target grid to interpolate to xi = yi = np. extrinsic. x y z data -12. In such a case, with linear. Learn more about interpolation, scatteredinterpolant, natural method, nan MATLAB. Interpolation and Extrapolation of Randomly Scattered data to Uniform Grid in 3D. You don't have to actually have the function, F, just the points that correspond to the x and y data points given. You need 2d interpolation over scattered data. Create a 10-by-10-by-10 grid of sample points. scatteredInterpolant を使用して、散布データの 2 次元または 3 次元データ セットの内挿を実行します。 scatteredInterpolant は指定したデータ セットの内挿 F を返します。 F をクエリ点の集合 (2 次元の (xq,yq) など) で評価して、内挿値 vq = F(xq,yq) を生成できます。Description. This produces a surface of the form V = F (X). For 3-D interpolation, the inputs x, y, and z define the points where the function v = f (x, y, z) is evaluated. I tried to us…There, you apply scatteredInterpolant in order to map your original data on a (equidistant) grid that is easy to plot. Copy. There are several general facilities available in SciPy for interpolation and smoothing for data in 1, 2, and higher dimensions. However, unlike scatteredInterpolant it does not always produce. and save to a mat file on disk. Thin-plate spline extrapolation uses the tpaps function, and PCHIP extrapolation uses the pchip function. 插值是在一组已知数据点的范围内添加新数据点的技术。. I have a shape defined by a point cloud. To use streamline, you need to convert this scattered data onto a grid. 3, matplotlib provides a griddata function that behaves similarly to the matlab version. Most recently, I’ve decided that the scatteredInterpolant function (as opposed to any gridded interpolation unless gridded interpolation is required) is significantly superior for these sorts of problems. For example, I have the following non-gridded data points, known v = F(x,y),. 24 25. Installing No build system. That has NOTHING to do with interpolation, and prediction of the original points in your set. You specify x and y as key / control points with the corresponding z and g output points. See the above example with nine points that represent four axis-parrallel elements. Learn more about scatteredinterpolant, fsolve Hi, I'm trying to implement solution of a nonlinear system, in which i'd like to use a scatteredInterpolant to calculate some values. Python bindings are also provided. Unfortunately MATLAB does not have any scattered interpolation routines that work in more than 3 dimensions, but gridded interpolation can. Specifically, the 'scatteredInterpolant' function defaults to the extrapolation method of 'linear' when the interpolation method is 'linear' or 'natural' and the extrapolation method of 'nearest' when the interpolation method is 'nearest,' as described in the documentation found below under 'ExtrapolationMethod':Learn more about interpolant, scattered interpolant, matlab, scatteredinterpolant, subsasgn Hey guys, I'm trying to build an interpolant which should give me interpolants for 8 different sample value vectors. scatteredInterpolant does a triangulation, and it is not uncommon for it to turn out that one of the three closest points to a given point can be from a different "layer" of Z. Z); f. griddedInterpolant evaluates each page in the 3-D image at. scatteredInterpolant provides functionality for approximating values at points that fall outside the convex hull. It is possible to fit a single polynomial interpolant to data, with a degree one less than the number of data points. Extrapolating Scattered Data Factors That Affect the Accuracy of Extrapolation. F = scatteredInterpolant (Xcoor, Ycoor, Zcoor,Cvapor); scatter3 (px,py,pz,4,F (px,py,pz),'filled');R equivalent to matlab griddata, scatteredInterpolant, and/or TriScatteredInterp. Dear Sir/Madam. >> F = scatteredInterpolant(xdata, ydata, vals, 'natural' , 'none' );Have you seen the interp2 function?. If you attempt to query at a location that is outside the outside boundary of the triangulation of the reference points, then it would need extrapolation but that is not enabled by default for 'linear'I am attempting to translate a bit of MATLAB code into python that involves three-dimensional interpolation. Learn more about scatteredinterpolant i have been trying to interpolate the wind speed of a known location on a meshed grid with changing sampe values (wind speed) recorded at weather station locations, the function below works for one. This can be done with griddata – below, we try out all of the interpolation methods: One can see that the exact result. Use scatteredInterpolant to perform interpolation on a 2-D or 3-D data set of scattered data . . Your data lies in the plane (x1,y1,0). I have tryed a lot with all possible other functions (pattern, griddata,. 974 5333045. Show what you did then. Share. Use scatteredInterpolant to perform interpolation on a 2-D or 3-D data set of scattered data . It makes sense since it does not have enough points to interpolate properly/sensibly. Es posible usar la interpolación para rellenar datos faltantes, suavizar datos existentes y hacer predicciones, entre otras cosas. Teams. v in the ScatteredInterpolant is just your data values at the x and y locations. . scatteredInterpolant giving null matrix. The scattered points in your volume make up a convex hull; a geometric shape with the following properties:. griddata. Vq = interp2 (V,k) returns the interpolated values on a refined grid formed by repeatedly halving the intervals k times in each dimension. With these three matrices I created one surface, and than I got more three matrices to create another one. F = scatteredInterpolant (x_repeat,x1 (:,3)); %rather than throwing an error, shows a warning and cleans your data for you. Description. Learn more about data, type, precision, input, arguments, cast, casting MATLABNatural-neighbor interpolation is a fast, robust, and reliable technique for reconstructing a surface from irregularly distributed sample points. 3 3; 3 3. Interpolation. random. scatteredInterpolant 는 지정된 데이터 세트에 대해 보간 함수 F 를 반환합니다. Over a given triangle, the interpolant is the linear. I was wondering if this process itself can be done in parallel processing because it takes VERY long for decently high resolutions (up to a hour for a 512x512x512 grid, which of course isn't trivial)I've written a code that uses TriScatteredInterp, but I read in Matlab's documentation that this will not be supported in future release and that I should instead use scatteredInterpolant. 18sec , griddenInterpolant:4. A brief explanantion of these functions is given below: griddata is a function in MATLAB that performs interpolation on scattered data to produce a grid. There is a high density of values scattered around in the center of the 3D space. scatteredInterpolant returns the interpolant F for the given data set. You can evaluate F at a set of query points, such as (xq,yq) in 2-D, to produce interpolated values vq = F (xq,yq). How to retain duplicate while using. Parameters: points 2-D ndarray of floats with shape (n, D), or length D tuple of 1-D ndarrays with shape (n,). I get the following warning from scatteredInterpolant. I tried to store the computed scatteredInterpolant objects for each time step in a cell array,. So you're sort of on the right track with meshgrid, though not diag. The surface can be evaluated at any query. For computational purposes, I need to resample them over a grid with a used-defined space discretization (say, 5 m). PchipInterpolator(x, y, axis=0, extrapolate=None) [source] #. However, before doing that, I created a mesh as a querry points. Hello. gridded data consist of data points at every node of an axis-aligned ND-grid. Use scatteredInterpolant to perform interpolation on a 2-D or 3-D data set of scattered data . e. This is a follow up to an earlier question: what I have is a 4 column text file denoting a point cloud with one column denoting data that I use for color, and three column entries for x y and z coordinates. Problem in using scatteredInterpolant . In a previous discussion Kelly provided a means to convert a scattered vector to gridded. scatteredInterpolant returns the interpolant F for the given data set. 18sec , griddenInterpolant:4. x and y are arrays of values used to approximate some function f, with y = f (x). I am making voxels(stl) from 2D image stacks using [scatteredInterpolant] function. Use griddedInterpolant to perform interpolation with gridded data. The values it returns for. Connect and share knowledge within a single location that is structured and easy to search. Then I query the interpolant over a set of points. Q&A for work. Each row of X contains the coordinates of one sample point. and I calculate with some formulas y=4. (PCHIP stands for Piecewise Cubic Hermite Interpolating. I have been looking for a C# (C or C++ equivalents are fine too) equivalent of Mathlabs TriScatteredInterp or scatteredInterpolant methods. When I did that step, command window shows " Requested 61890x61890 (28. This allows the object to continue using the same triangulation it built when it was originally constructed, which is a lot of the work involved in creating the object. You can either search for the duplicates and shift them by ± eps, average them together, or discard them. Link. This discussion applies in any dimensionality. This normalization is very common and is also called standardization. scipy. interp2 is a wrapper for griddedInterpolant. This class returns a function whose call method uses spline interpolation to find the value of new points. Q&A for work. There is no need to use griddata AFTER you used scatteredInterpolant! Here is your data. So I tried the scatteredInterpolant for it. random(100) z = np. To install, run. I have a 256 x 256 x 32 grid of regularly spaced points ranging over x, y, and z and with an. All. Interpolation is interpolation. m' (which creates the 'scatteredInterpolant' object). But without seeing the data, I am left with suggesting that POSSIBLY, one of those alternatives would be a better choice than the use of. scatteredInterpolant contains data and it behaves like an array—in MATLAB language, it is called a value object. % Section Classification Flange width to thickness ratio in compression. For more information about griddata, griddata3 and griddatan read octave documentation. This method fits smooth surfaces that also extrapolate well (for surfaces only). interpolate. Learn how to use scatteredInterpolant to perform interpolation on a 2-D or 3-D data set of scattered data. This would be akin to filtering a full 2-D array using the 'replicate' argument as opposed. This is a fast algorithm for scattered N-dimensional data interpolation and approximation. Interp = scatteredInterpolant (supportPts (:,1),supportPts (:,2),Fval); %evaluate at center of bottom left element. Use griddedInterpolant to perform interpolation with gridded data. Each row of X contains the coordinates of one sample point. problem with scatteredInterpolant: are there any. % Class 2 taken to be the upper limit as same procedure as Class 1. You can evaluate F at a set of query points, such as (xq,yq) in 2-D, to produce interpolated values vq = F(xq,yq). In some cases you can have a set of x and y data where the values of x and/or y are repeated as Aristo was showing. 5GB) array exceeds maximum array size preference. scatteredInterpolant supports (x, y, v, then options, or (x, y, z, v, then options, so building an interpolation object over 2d or over 3d, that you then invoke with the appropriate number of input parameters to get results. f = scatteredInterpolant(contour_grid. 2 Answers. For your 3D case lets talk about computational geometry first, to understand why part of the region gives NaN from griddata. MATLAB ® 中的插值技术可分为适用于网格上的数据点和散点数据点。. The values in the x-matrix are strictly monotonic and increasing along the rows. You apparently used scatteredInterpolant, but it makes a choice about HOW to interpolate the points, and you do not like the result. The subject line could equally. function data_out = test_scatteredInterpolant (data_input) U = rand (20,20); V = rand (20,20);Vq = interp3(X,Y,Z,V,Xq,Yq,Zq) returns interpolated values of a function of three variables at specific query points using linear interpolation. scatteredInterpolant supports (x, y, v, then options, or (x, y, z, v, then options, so building an interpolation object over 2d or over 3d, that you then invoke with the appropriate number of input parameters to get results. griddata# scipy. You can evaluate F at a set of query points, such as (xq,yq) in 2-D, to produce interpolated values vq = F (xq,yq). Use scatteredInterpolant to perform interpolation on a 2-D or 3-D data set of scattered data . One approach would be to replace the NaN values with nearest-neighbor interpolates using scatteredInterpolant (or TriScatteredInterp in older MATLAB versions) before performing the filtering, then replacing those points again with NaN values afterward. Answers (1) Githin John on 27 Jan 2020. bash-script scattered-data-interpolation. I tried to put the 'ExtrapolationMethod' option. Use griddedInterpolant to perform interpolation with gridded data. n(goodT),map. The griddata function supports 2-D scattered data interpolation. We often interpolate from solutions rather than rerun every case. y at z=0, I use griddata command to reshape my velocity vector into same n. x = [1. Scattered data interpolation methods for electronic imaging systems: a survey Isaac Amidror Laboratoire de Syste`mes Pe´riphe´riques Ecole Polytechnique Fe´de´rale de LausannescatteredInterpolant contains data and it behaves like an array—in MATLAB language, it is called a value object. A simple way around is to add some noise to your data as with randn then ScatterInterpolant does not consider the values to be equal and it works for me. if your data is already sorted in arrays, consider to use MathNet. The Analytic, Interpolation, and Piecewise functions can also be added to Materials. MATLAB software also provides griddatan to support interpolation in higher dimensions. Besides splitting the creation of the object from the invocation for interpolation purposes, griddata simply does not. [new_lons,new_lats] =. 0884. Parameters: pointsndarray of floats, shape (npoints, ndims); or Delaunay. mean_velocity); [xGrid,yGrid] = meshgrid (linspace (xmin,xmax,20),linspace (ymin,ymax,20));In matlab it has the nice property that it creates an interpolant that I can evaluate at few selected points a lot faster than creating the interpolated griddata over the whole domain. I get the following warning from scatteredInterpolant. The currently preferred way to perform scattered data interpolation is via the scatteredInterpolant object class: >> F = scatteredInterpolant (. LinearNDInterpolator(points, values, fill_value=np. Then use the property 'Constraints' to specify the edges along the boundary of the actual domain you want to plot. The surface is always convex (as the name suggests)Use scatteredInterpolant to perform interpolation on a 2-D or 3-D data set of scattered data . interpolate. You appear to be wanting to do an 11-dimensional scattered interpolation. Unfortunately MATLAB does not have any scattered interpolation routines that work in more than 3 dimensions, but gridded interpolation can. Av = x (3)*x (4); % mm2 the web area when load is parallel to web. Use scatteredInterpolant to perform interpolation on a 2-D or 3-D data set of scattered data . That is, for each 5 pixels in the original image, the interpolated image has 6 pixels. arange(0,1. eps= (235/fy)^ (1/2); % required for section classification. when using 'linear' as a method to interpolate the field, I get an answer and all is fine but precision wise it's not so grea.