Multiple colormaps with surface and patch

Hi all...

My question is a variation on the theme of the use of the multiple colormap on the same figure/axis, but with the additional issue of handling a surface and a patch at the same time...

I have to display an image (an ortophoto) overlapped to a 3D surface (a digital elevation model of the land) and, at the same time a patched section (an isocap) of a volume of a certain variable (the salinity) simulated by a oceanographyc model.

I cannot use the common geoshow or mapshow commands to display the geotiff image because of the 3D view and the need to overlap it on a 3D surface. I have to use the command "surface" with the texturemap option.

So:

Let's load the image:

% Loading ortophoto
[Orto, R, bbox] = geotiffread('.\GIS\Geotiff.tif');
% Convert to index color data to display as a texture map
[Co,map] = rgb2ind(Orto(:,:,1:3),256);

Let's assume that 'Zo' is the surface 3D data, with his corresponding Xo and Yo coordinate grids.

Let's plot the overlapped image on the surface data:

Ort = surface(Xo,Yo,Zo,Co,'FaceColor','texturemap','EdgeColor','none',...
  'CDataMapping','direct');

and let's apply the proper colormap.

colormap(map)

Now let's display the section "Ssect" (isocap):

c = patch(Ssect,'FaceColor','interp','EdgeColor','none');

and let's apply its proper colormap:

colormap(hsv)

As known, the last "colormap" command overwrite the first one.

I tried to apply the product support answer http://www.mathworks.es/support/tech-notes/1200/1215.html and the other http://www.mathworks.es/help/techdoc/creating_plots/bqsxy8a-1.html#brdjjbz-1, but they are not directly appliable to patch surface.

I can understand the principle to break the colormap and reserve part of it for one element and part for another one, but I don't know how to do it when facing with a surface and a patch at the same time.

Please note that the first colormap (map) is not a linearly varying standard colormap but a discrete-values colormap deriving from the coding of RGB values of the image.

Thanks in advance

Simone

Answer 1

[Bjorn Gustavsson]

Maybe you can circumvent some of your problems with these tools from the file exchange: http://www.mathworks.co.uk/matlabcentral/fileexchange/3777-tcolor-a-fast-pcolor-that-likes-rgb-images http://www.mathworks.co.uk/matlabcentral/fileexchange/7943-freezecolors-unfreezecolors http://www.mathworks.co.uk/matlabcentral/fileexchange/24371-colormap-and-colorbar-utilities-sep-2009

TCOLOR is a tool which replaces pcolor/surf for rgb-images, FREEZECOLORS makes it possible to use multiple colormaps in one figure, and the same capability exists in the COLORMAP-AND-COLORBAR-UTUILITIES.

If the worst comes to the worst maybe you simply have to plot the orto-photo pixel-by-pixel as patches with their facecolor set to the RGB values - unreasonably tedious but shold get the job done.

HTH.

Answer 2

[Walter Roberson]

Is there a particular reason why the geotiff image must be converted to pseudocolor? surface() accepts truecolor (RGB) data for the color property.

Answer 3

[Simone]

THANK you!!!! Sorry for my late answer.... Actually I cannot use freezecolors with surface, patch and pseudocolor surface together, but, with Walter's suggestion (to keep the original RGB data), I can employ the freezecolor and colormap/bar utilities successfully....

Thank you so much... Simone