Difference between revisions of "Gnuplot/C2/Generate-3D-plots-and-surfaces/English"
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|| '''Slide Number 10''' | || '''Slide Number 10''' | ||
'''Assignment''' | '''Assignment''' | ||
| + | Hint: | ||
Equation for a sphere centered at (x1,y1,z1) in polar coordinates is shown here. | Equation for a sphere centered at (x1,y1,z1) in polar coordinates is shown here. | ||
| + | |||
x1+r.sin(u).cos(v), y1+r.sin(u).sin(v), z1+r.cos(u) | 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. |
|- | |- | ||
Revision as of 11:38, 6 December 2019
| Visual Cue | Narration |
| Slide Number 1
Title Slide Generate 3D plot and surfaces |
Welcome to the tutorial on Generate 3D plot and Surfaces. |
| Slide Number 2
Learning Objectives |
In this tutorial we will learn to,
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| Slide Number 3
Learning Objectives |
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| Slide Number 4
System and Software Requirement |
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| Slide Number 5
Pre-requisites |
To follow this tutorial,
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| 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.
The splot command generates 3D graph in the graphics window. Make sure x and y are in parenthesis. |
| Cursor on 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 finer 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 change in the graphic window while rotating the graph. |
| Close the graphic window. | Next, we will plot a sphere in gnuplot.
Close the graphics window. |
| Slide number 6
Equation for a sphere This function can be plotted in polar coordinates as, r.sin(u).cos(v), r.sin(u).sin(v),r.cos(u) |
Equation of a sphere with radius r, centered at (0,0,0) is shown.
It is, x square plus y square plus z square is equal to r square. This function can be plotted in polar coordinates as seen here. |
| Cursor on the slide. | We will write a script to draw a sphere in gnuplot using a 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. |
| 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.
Press Enter. |
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 the parameters u and v.
Here we have Polar coordinates. |
| 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. |
| Type,
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 gnuplot terminal. |
| 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 gedit 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 .
This is part of the splot command line. |
| Press Ctrl+S . | Save the changes in the script file. |
| Come back to gnuplot . | Come back to the terminal with the gnuplot prompt.
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. |
| 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 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. | It is called a colorbox in gnuplot.
The values between 1 to 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 terminal. | Practice and familiarize with commands and styles.
Learners can also use the help command for this purpose. |
| Slide Number 7
Summary |
To summarize, in this tutorial, we,
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| Slide Number 8
Summary |
* Plotted a sphere and changed the color
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| Slide Number 9
Assignment |
For assignment, plot the following,
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| Slide Number 10
Assignment Hint: Equation for a sphere centered at (x1,y1,z1) in polar coordinates is shown 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
Acknowledgement |
Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India. |
| This is Rani from IIT Bombay.
Thank you for joining. |
