| Slide Number 1
Generate 3D plot and surfaces
|Welcome to the tutorial on Generate 3D plot and Surfaces.|
| Slide Number 2
| In this tutorial we will learn to,
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| Slide Number 4
| Slide Number 5
| To follow this tutorial,
|Press Ctrl+Alt+T.||Open a terminal.|
|Type cd Desktop and press Enter.||Change the directory to Desktop.|
|Type gnuplot and press Enter.||I will open gnuplot from Desktop directory in the terminal.|
|Press Ctrl+L.|| I will also clear the screen.
We will plot the function, cos x cos y to draw a surface.
|Type splot cos(x)*cos(y) and press Enter.|| Enter the command splot space cos x times cos y.
Make sure x and y are in parenthesis.
|Cursor on the graphics window.|| The splot command generates 3D graph in the graphics window.
Besides x and y, the third axis is the value of the function in the plot.
|Hold down left mouse key and turn around and rotate the plot.|| Hold down the left mouse key.
Move the mouse to rotate the graph and change the viewing angle.
|Zoom into the graph.|| Zoom in slightly into the graph to see a wavy surface.
Notice the surface is plotted in a wide mesh style.
|Cursor on the graphics window.||Let's change some of the properties of the surface.|
|Hover mouse over the two sides of the surface.||We will color both sides of the surface differently.|
| Enter the command set hidden3d .
Enter the command replot.
| The required command for this is set space hidden3d .
Enter the command replot, to see the changed colors.
|Show the two colors on the screen.||Notice the hidden surface is colored green and the top surface is purple.|
|Type set isosamples 50,50 and press Enter.|| Let’s divide the surface into a fine grid.
Enter the command, set space isosamples space 50 comma 50.
|Type replot and press Enter.||Replot to notice a fine mesh defining the surface.|
|Cursor on the graphics window.||Use the command, help space splot to know more about the splot command.|
|Hold down the left mouse key and move the mouse.||Hold down the left mouse key and move the mouse to rotate the graph.|
| Cursor on the view angle value, in the graphics window.
Highlight the changed angle in the graphics window during video editing.
|The viewing angle changes in the graphic window while rotating the graph.|
|Click on Close button to close the graphic window.|| Next, we will plot a sphere in gnuplot.
Close the graphics window.
| Slide number 6
Equation for a Sphere
| Equation for a sphere with radius r, centered at x0, y0, and z0 is shown here.
It is, x square plus y square plus z square is equal to r square.
This function can be plotted in parametric mode as seen here.
|Cursor on the slide.|| We will write a script to draw a sphere in gnuplot using the text editor.
Then run the script file to plot a graph.
| Press Ctrl+Alt+T.
Type gedit and press Enter.
|Open another terminal and type gedit to open a gedit window.|
|Cursor on Gedit text editor.||Windows users may use notepad or wordpad software.|
|Type # my first 3D plot and press Enter.|| Let's enter a comment on the first line.
I will type hash my first 3D plot and press Enter to start a newline.
The comments start with a hash.
|Type the commands in the text editor.||Next, please type the commands as shown here.|
|Type set parametric and press Enter.||First, set the plot to parametric mode.|
| Type set angle degree.
|Then set the angle to degree .|
| Enter the 2 lines
set urange [0:360]
set vrange [0:180]
and press Enter.
|Next, specify the ranges of parameters u and v.|
|Type set isosample 50,50 and press Enter.||Set isosamples to make a fine mesh.|
|Type set ticslevel 0 and press Enter.|| Set ticks level to zero.
This sets the XY plane at zero value of Z axis.
|Type r=1 and press Enter.||I will set the radius of the sphere to one.|
splot r*sin(u)*cos(v), r*sin(u)*sin(v),r*cos(u) and press Enter.
|Next add the line, splot space and the function for sphere as seen.|
|Press Ctrl+ S.||Press Control S to save the file.|
| Give file name, sphere.dem in path desktop folder.
Click on Save.
| A dialogue box opens.
I will save the file in Desktop folder with filename sphere.dem.
Click on Save to save the script.
|Minimize gedit and go to terminal.|| Click on the hyphen sign on the top to minimize the gedit window.
Go back to the terminal, where gnuplot is open.
|Cursor on terminal.|| If you had closed gnuplot, please open gnuplot again.
Let's run the script to generate a sphere.
|Enter the command load 'sphere.dem' .||Enter the command, load space within single quotes sphere dot dem.|
|Point to the sphere in graphics window.||A sphere, centered at zero, zero, zero with radius one appears on the screen.|
|Rotate the sphere.|| Let’s change the color of the sphere to blue.
We will edit the script file to make the required changes.
|Go to the gedit script .|| Go to the edit window to edit the script.
If you had closed it, please open the script file to edit.
|Add lc rgb 'blue' in the end of the splot command.|| Add lc space rgb space within single quotes blue.
|Press Ctrl+S .||Save the changes in the script file.|
|Come back to gnuplot .||Come back to the gnuplot prompt and load the edited script file again.|
|Type load 'sphere.dem' and press Enter.|| Enter the command load space within single quotes sphere.dem.
In some systems, pressing the up arrow key scrolls through the command history.
|Show the blue sphere.||Notice the blue sphere in the graphics window.|
|Cursor on the graphics window.||Next, let's make a heatmap with pm3d command.|
| Select and delete the part,
lc rgb blue .
| Go back to the script in gedit to make changes in it.
Delete the lc space rgb space blue in the splot command.
|Type with pm3d at the end of the same line.||Add, with space pm3d at the end of the line, as seen on the screen.|
|Press Ctrl+S, minimize gedit and go to gnuplot.||Save the script file, minimize gedit and go to gnuplot.|
|Enter command load 'sphere.dem' .||Load the sphere.dem script again.|
|Point mouse next to the map guide in graphics window.|| Notice the heatmap in the sphere.
The color scale bar for the color gradient, is visible on the side.
|Hover mouse on the range guide range.|| This is called a colorbox in gnuplot.
The values between 1 and 0.8 are colored in yellow.
Values between minus 0.8 to minus 1 are colored in deep purple.
|Cursor on the graphics window.||Using scripts, we can generate and make changes in the graph.|
|Exit gnuplot and gedit.|| Let’s exit gnuplot and gedit.
Similar scripts are available in gnuplot demo website.
|Cursor on the terminal.|| Practise and familiarize with commands and styles.
Learners can also use the help command for this purpose.
|Type q to quit gnuplot and close gedit.||Let's exit gnuplot and gedit.|
| Slide Number 7
| To summarize, in this tutorial, we,
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| Slide Number 9
| For assignment, plot the following,
| Slide Number 10
Hint: For a sphere centered at (x1,y1,z1), use the equation for sphere as seen here.
x1+r.sin(u).cos(v), y1+r.sin(u).sin(v), z1+r.cos(u)
|For a sphere centered at (x1,y1,z1), use the equation for sphere as seen here.|
|Show assignment screenshot.||Your completed assignment look similar to this.|
| Slide Number 11
Spoken Tutorial Project
| This video summarises the Spoken Tutorial Project.
Please download and watch it.
| Slide Number 12
Spoken Tutorial workshops
| We conduct workshops and give certificates.
For more details, please write to us.
| Slide Number 13
Forum for Specific Questions:
|Post your timed queries in the forum.|
| Slide Number 14
|Spoken Tutorial Project is funded by MHRD, Government of India.|
| This is Rani from IIT Bombay.
Thank you for joining.