displaying RGB colours using SURF.

I am trying to display a rgb colour map on a gridded surface using surf.

I have grids of each rgb colour. How do I combine to give the surf(x,y,z,C)?

thanks

[Sian Allerton]

thanks all, solved. Created C as nx,ny,3(rgb) matrix.

[Image Analyst]

For the benefit of others, could you provide a small demo?

I'm attaching mine (which is based Bruno's method below).

[Ameer Hamza]

It should be "based on Ameer's method" :P

[Sian Allerton]

the issue was how to structure an image variable. i wasn't starting from an image, but a set of rgb points.

% x,y,z point cloud poitions in temp(:,1:3)
% rgb levels for points in temp(:,4:6)
% first grid the point data and the colour data.
x = temp(:,1);
y = temp(:,2);
z = temp(:,3);

%define grid 
xmax = max(x);
xmin = min(x);
ymax = max(y);
ymin = min(y);
n = 1000;
m = 1000;
xs = (xmax-xmin)/n;
ys = (ymax-ymin)/m;

[gx,gy]= meshgrid(xmin:xs:xmax,ymin:ys:ymax);
gz = griddata(x,y,z,gx,gy);
gr = griddata(x,y,temp(:,4),gx,gy, "nearest");% red
gg = griddata(x,y,temp(:,5),gx,gy, "nearest");% green
gb = griddata(x,y,temp(:,6),gx,gy, "nearest");% blue
gc(:,:,1)  = gr; % red 
gc(:,:,2) = gg;  % green
gc(:,:,3) = gb;  % blue
%normalise colours
gcc= gc/256;
surf(gx,gy,gz,gcc);

Thanks for everyone's comments. The image is of a Scottish hill fort from drone data btw.

[Walter Roberson]

I suggest using warp()

[Image Analyst]

Sorry Ameer, you're absolutely right. Sometimes I work on too many problems too close together. I must have gotten confused.

Answer 1

[Ameer Hamza]

You can use texture mapping to display an RGB image on a surface(). See here: https://www.mathworks.com/matlabcentral/answers/91858-is-it-possible-to-perform-texture-mapping-within-matlab. For example

img = imread('pears.png');
z = peaks(100);
surf(z, ...
    'FaceColor','texturemap',...
    'EdgeColor','none',...
    'Cdata',img)
view(3)

[Image Analyst]