how to plot 3d surface maps? interpolation?

Hi All,

i am struggeling to have a correct interpolation (IDW) for 3d surface maps for the spatial analysis of the parameters collected by CTD to plot temperature (as an example). There is something wrong!

any help is very much appreciated

the steps are below:

1- list of mat fiels each of this mat files contains T table inside (screenshot shows).

2- download the mat fiels

3- grid the data from mulitple CTD locations

4- Surface maps with the coastlines

dataDir = '/';   
files = dir(fullfile(dataDir, '*.mat'));
T_all = table();
for i = 1:length(files)
    fname = fullfile(dataDir, files(i).name);
    S = load(fname);
    if isfield(S,'T')
        Ti = S.T;
        Ti.SourceFile = repmat(string(files(i).name), height(Ti), 1);
        Tall = [Tall; Ti];
    else
        warning('%s does not contain table T', files(i).name)
    end
end
depth_target = 2.0;   % meters
tol = 0.5;            % ±0.5 m
Tz = Tall(abs(Tall.Depth_m - depth_target) <= tol, :);
[G, station, date] = findgroups(Tz.Station, Tz.Date);

Tmap = table();
Tmap.Station = station;
Tmap.Date = date;
Tmap.Lat = splitapply(@mean, Tz.Lat, G);
Tmap.Lon = splitapply(@mean, Tz.Lon, G);
Tmap.Temp = splitapply(@mean, Tz.Temp_C, G);

min_map_lon = 35.2;
max_map_lon = 37.2;
min_map_lat = 25.1;
max_map_lat = 27.6;

[LonGrid, LatGrid] = meshgrid( ...
    linspace(min_map_lon, max_map_lon, 250), ...
    linspace(min_map_lat, max_map_lat, 250));

TempGrid = griddata( ...
    Tmap.Lon, Tmap.Lat, Tmap.Temp, ...
    LonGrid, LatGrid, 'v4');   % IDW

load RS_bathy_gebgo   % longitude, latitude, bathy
orient portrait
figure
hold on
m_proj('mercator', ...
    'lon',[min_map_lon max_map_lon], ...
    'lat',[min_map_lat max_map_lat]);

m_pcolor(longitude, latitude, bathy);
shading interp
colormap(flipud(gray))
caxis([-1200 0])

h = m_pcolor(LonGrid, LatGrid, TempGrid);
set(h,'FaceAlpha',0.85)   % transparency so bathy shows
shading interp
colormap(turbo)

m_usercoast('red_sea_f','patch',[0.8 0.8 0.8])

m_grid('contour','on','tickdir','out', ...
    'box','fancy','fontsize',10, ...
    'linewidth',1,'linestyle','--');
colorbar
ylabel('Latitude','fontsize',16,'fontweight','bold');
xlabel('Longitude','fontsize',16,'fontweight','bold');

[Mathieu NOE]

hello

could you please share a couple of mat files (size < 5Mb if possible)

[Star Strider]

You appear to be using something other than the Mapping Toolbox functions for this. It seems to have a number of interpolation and surface plotting functions specific to geographic coordinates.

You need to supply the functions you are calling, a link to the third-party toolbox you are using, as well as supplying the data (if possible) to get help with this.