# How to plot pixels on the figure when I have coordinates of the center of each pixel

5 views (last 30 days)
Behzad Navidi on 5 May 2020
Commented: Ameer Hamza on 7 May 2020
Hello,
I have the coordinates of the center of 93 0.5x0.5 pixels.
I want to plot them like this picture:
Here is my data which contains latitude, longitude, and also value.
Any suggestion or advice is highly appreciated.

Ameer Hamza on 5 May 2020
Edited: Ameer Hamza on 5 May 2020
Try scatteredInterpolant()
x = points{:,1};
y = points{:,2};
z = points{:,3};
interp_model = scatteredInterpolant(x, y, z);
xg = linspace(min(x), max(x), 100);
yg = linspace(min(y), max(y), 100);
[Xg, Yg] = meshgrid(xg, yg);
Zg = interp_model(Xg, Yg);
pcolor(Xg, Yg, Zg)
after pcolor() to get a smooth surface

Ameer Hamza on 6 May 2020
I am glad to be of help.
Behzad Navidi on 7 May 2020
Dear Ameer Hamza,
I'm sorry but I have another problem here.
When I start comparing the figure from the first model and second model's pixels I found that the values of the color bar are different while the colors of pixels are similar. For example please look at these two pictures, the first one generated for the first model and the second one generated for the next model:
I have a yellow color in both but in the first one, it indicates values near 350 while in second figure yellow pixels show values about 140.
In order to compare, do you think there is any way to make color stable in both?
For example, yellow color in all figures of models shows near 300 values.
Here is an example and I have to compare more than 20 models.
Thank you again for your help.
Ameer Hamza on 7 May 2020
Yes, It is possible, but that will make the points in some figures to be very similar. For example, If you set the limits of the color axis from 0 to 400 for all figures, then if the points lie between [127 130], they will have a very similar color. Try following code. I set the limits of color axis as [0 400]
%%
mapshow(s)
hold on
axis equal
ax = gca;
xL = ax.XLim;
yL = ax.YLim;
%%
rect_x = [-0.25 -0.25 0.25 0.25];
rect_y = [0.25 -0.25 -0.25 0.25];
x = points{:,1};
y = points{:,2};
z = points{:,3};
num_colors = 200;
clrs = summer(num_colors);
zlim = [0 400];
clr_val = @(z) clrs(ceil(interp1(zlim, [0 1], z)*num_colors), :);
for i=1:numel(x)
p(i) = patch(rect_x + x(i), rect_y + y(i), ...
clr_val(z(i)), ...
'EdgeColor', 'none');
end
ax.XLim = xL;
ax.YLim = yL;
colorbar
colormap(summer)
caxis(zlim)