MATLAB: Give a range of Z axis instead of X and Y when graphing a surface

creating limits on z axisSymbolic Math Toolbox

Hi guys,

I am trying to graph a surface below, but instead of giving it x and y restrictions like how I have given it, can I graph in a certain range of Z values and see what X and Y values it comes up with? For example, with the surface below I want it to graph the surface between Z values of 20 and 30. Is this possible? Thanks!

x = [0:500];
y = [0:500];
[X,Y] = meshgrid(x,y);
surface1 = @(x,y) x + y;
S1 = surface1(X,Y);
surf(X,Y,S1)

Best Answer

Perhaps this is what you want:

x = 0:500;
y = 0:500;
[X,Y] = meshgrid(x,y);
surface1 = @(x,y) x + y;
subplot(2,1,1);
S1 = surface1(X,Y);
surf(X,Y,S1, 'edgecolor', 'none')
title('S1', 'FontSize', 40);
% Find out where S1 is between 20 and 30
binaryMap = S1 >= 20 & S1 <= 30;
[rows, columns] = find(binaryMap);
xLeft = min(columns)
xRight = max(columns)
yTop = min(rows)
yBottom = max(rows)
S2 = S1; % Initialize
% Set to NaN where outside range so it will be invisible.
S2(~binaryMap) = nan;
% Crop to desired region;
S2 = S2(yTop:yBottom, xLeft:xRight);
subplot(2,1,2);
surf(x(xLeft:xRight), y(yTop:yBottom), S2);
title('S2', 'FontSize', 40);
% Set up figure properties:
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0.5 0 0.3 1]);
% Get rid of tool bar and pulldown menus that are along top of figure.
set(gcf, 'Toolbar', 'none', 'Menu', 'none');
% Give a name to the title bar.
set(gcf, 'Name', 'Demo by ImageAnalyst', 'NumberTitle', 'Off')

Related Solutions

MATLAB: Fill a gap on an image surface

Can you threshold it? If that gives an OK boundary except for that gap, then use the boundary() function.

Try this:

clc;    % Clear the command window.
clear all;
close all;  % Close all figures (except those of imtool.)
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 16;
%===============================================================================
% Get the name of the image the user wants to use.
baseFileName = 'bone_image.jpeg';
folder = pwd;
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~exist(fullFileName, 'file')
	% The file doesn't exist -- didn't find it there in that folder.
	% Check the entire search path (other folders) for the file by stripping off the folder.
	fullFileNameOnSearchPath = baseFileName; % No path this time.
	if ~exist(fullFileNameOnSearchPath, 'file')
		% Still didn't find it.  Alert user.
		errorMessage = sprintf('Error: %s does not exist in the search path folders.', fullFileName);
		uiwait(warndlg(errorMessage));
		return;
	end
end
%=======================================================================================
% Read in demo image.
grayImage = imread(fullFileName);
% Get the dimensions of the image.
[rows, columns, numberOfColorChannels] = size(grayImage)
if numberOfColorChannels > 1
	grayImage = rgb2gray(grayImage);
end
% Display image.

subplot(2, 2, 1);
imshow(grayImage, []);
impixelinfo;
axis on;
caption = sprintf('Original Image\n%s', baseFileName);
title(caption, 'FontSize', fontSize, 'Interpreter', 'None');
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.
% Set up figure properties:
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0.05 1 0.95]);
% Get rid of tool bar and pulldown menus that are along top of figure.
% set(gcf, 'Toolbar', 'none', 'Menu', 'none');
% Give a name to the title bar.
set(gcf, 'Name', 'Demo by ImageAnalyst', 'NumberTitle', 'Off')
drawnow;
% Crop off white frame surrounding the image.
grayImage = grayImage(5:645, 6:647);
%===================================================================================
% Get a histogram
subplot(2, 2, 2);
histogram(grayImage);
grid on;
title('Histogram of gray scale image', 'FontSize', fontSize, 'Interpreter', 'None');
% Convert to binary
% binaryImage = imbinarize(grayImage);
binaryImage = grayImage > 50;
% Fill blob and take the largest one.
binaryImage = bwareafilt(imfill(binaryImage, 'holes'), 1);
% Display image.
subplot(2, 2, 3);
imshow(binaryImage, []);
impixelinfo;
axis on;
title('Original Boundary', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;
% Get outline
boundaries = bwboundaries(binaryImage);
x = boundaries{1}(:, 2);
y = boundaries{1}(:, 1);
hold on;
plot(x, y, 'r-', 'LineWidth', 3);
% Get the boundary
b = boundary(x, y, 0.9);
subplot(2, 2, 4);
imshow(binaryImage);
hold on;
plot(x(b), y(b), 'r-', 'LineWidth', 3);
axis image; % Make sure image is not artificially stretched because of screen's aspect ratio.
caption = sprintf('Boundary without Gap.');
title(caption, 'FontSize', fontSize);

MATLAB: Fsolve How to pass several functions

f=@(x,y) [x+y^2-5; x+y-3];
z = fsolve(@(p) f(p(1),p(2)),x0);

Best Answer

Related Solutions

MATLAB: Fill a gap on an image surface

MATLAB: Fsolve How to pass several functions

Related Question