Pumpkin Tutorial
Created by Gordon Patterson
Instructor Hudson’s Bay High School
June 28, 2005
Rhino Skills: Circle, curve, join, rail revolve, split, hide or change layer and turn off. Trim a 3d shape with a 2d shape. Lighting and rendering with materials.
1. Start a new file, go with default setting. Save as Pumpkin etc.
If you want to choose a different setting, type units and hit enter, the dialog box will open. The Default setting for Model units is Millimeters. This can be changed to other metric units or SI units like inches, feet etc.
If you change to inches it is recommended that you also change Absolute tolerance to .001.
2. In the Top view port, draw a “Circle” with a radius between 8 and 12 millimeters. Note that the circle center is located at intersection of the X and Y axis. To do this toggle snap and draw a circle with a radius starting at the (0,0)
3. Use “Curve” with Osnap on toggle near and end. Note this curve has 7 control points or places were left clicks were made to place it.
4. You need to make curves all the way around the circle. You are going to make a two dimensional cross section of a pumpkin.
5. Join all the curves. First hide or turn the black layer off. Next select all of the curves then join. Note if you have done it correctly when you select the curve it will light up all the way around.
Right click on hide and everything that you have hidden will reappear.
6. From the center of the circle draw a line straight down with Ortho on. Or hold shift to temporarily activate the Ortho snap. In front view the line should be from 4 to 6 units long. Note the point has been placed in the top view to help make it clear that the line is also centered on the origin just as the circle is.
7. In the front view draw a curve the shape of the letter “C” with planer on. Osnap should be set to end and near. Note if your curve extends beyond the Z axis draw a straight line from center, with Ortho on, up beyond the curve and trim.
8. When drawing the “C” shaped curve, it should connect the white curve on the “Y” axis in the top view. Note from the top view the “C” shaped curve is straight.
9. Rail revolve step by step
Go to the Surface menu at the top of the screen.
Drop down to Rail Revolve.
Select the profile curve “C” shaped curve.
Next select the rail curve; this would be the white bumps that were joined earlier in the top view.
Finally select the start and end of the RailRevolve. This would be the end points of the “C” shape curve.
As soon as you select the last endpoint your pumpkin should be generated.
This is actually a model of a miniature pumpkin or squash.
Carving the pumpkin
10 . First it’s a good idea to make a copy of your pumpkin if you are happy with its shape.
11. Move one pumpkin away from the others, hide the other pumpkin or place the other pumpkins on a different layer and turn that layer off. This last method has the advantage of staying off when you right click on hide.
12. Split the remaining pumpkin in half. You may need to explode the surface of the pumpkin first, you will be able to join it back together later.
13. In the top view change layers and draw a straight line though the center of the pumpkin. Select line, use snap and click on the origin. Hold shift and click on the far side of the pumpkin.
14. Explode the surface of the pumpkin. Next extrude straight the line in the front view. Go to the Surface menu drop down to Extrude curve, move over to straight. Select the line hit enter and type the letter B, the line will extrude both ways at the same time.
15. Select split, or type it. Use a crossing window to select the top half of the pumpkin.
Select the surface of the extruded line and enter.
The command line should tell you if it split.
16. Delete the line and the surface that you extruded.
17. In the top view select the top half of the pumpkin and “hide” it.
18. Double click on the word Front. This will change the view from four windows to that window.
19. Now you are ready to draw the shape (Face) that you will use to trim (carve) you pumpkin with. Note it is best to draw the face to the side then move it over later. Note each shape (eyes, nose, mouth) must be joined. Only joined closed shapes will trim.
20. Move your design in place, you may want to change the scale or move part of it once you see it on the surface.
21. Trim. You are now ready to trim. Select trim or type it. Select the cutting line then the surface inside it. You should see the surface disappear.
22. The above image was placed on a gold layer then it was shaded. This is not a render.
Materials and lighting .
23 . Make sure that the render is set to Flamingo Raytrace.
24. Right click on hide to show your entire pumpkin. Note: do this in top view.
The reason there are 2 colors is because the front of the pumpkin was placed on a gold layer.
25. Select all surfaces with a crossing window and select join. Note: if you do it correctly it will all be one color.
26 . Select your surface and click on properties. To activate Properties select the multicolored circle next to the red, white and blue pie shape.
27. When the properties dialog box opens select Object and pull down to material.
28. Under “Assign by” select Plug-in
29 . Select Browse next and if you have Flamingo you will get a material library.
30 . If you want to start conservative go to plastic. Because pumpkins have a texture you might want to select Textured. Pumpkins are orange so select orange.
31. Now render to see what you have done. Note this first render is with ambient light and a default background.
Lighting
32 . Place a point light inside the pumpkin to make it look like there is a candle burning inside it. To do this you will need to select the spot light and hold down for options. The point light is the second one over. Note lights turn ambient light off.
When done render
33 . Change the background to black so it looks like it is night time. To do this, activate document properties. This can be done by right clicking on the blue sphere or going to the render menu and dropping down to proprieties.
34. In the document properties dialog box select Environment, next to sun near the bottom.
35. Under Main, Background Color, make sure that Solid color is selected. Click on the Gray rectangle above the word Advanced.
36. Find and select black. Note you will need to select ok about three times to get back to you screen before you can render.
37. Render again. Select the blue sphere. Note one way to get rid of the light that outlines the pumpkin in this picture is to save it as a JEPG or bitmap then open it up in the paint program and black out the spots that are not black.
The most difficult lighting effects are to see the light in the pumpkin and see the pumpkin at the same time. Also to see the pumpkin and have it cast a light on a surface is harder.
38. First in the top view add a directional light. Make sure that the directional light is facing the front of the pumpkin. Select the spotlight and hold down for options.
39 . Now render.
40. You may need to turn the intensity of the directional light down and the intensity of the point light up to achieve the affect you like. The light must be selected before you can activate its properties. Note it takes a few attempts at rendering to get something you like.
41 . The picture below shows the number that the directional light has been changed to. (Shadow intensity, Spotlight hardness and Light Intensity) are the 3 factors that you can control. These were not the default setting for this light.
Select the point light next and turn its intensity up to about 90 everything else is left at 100.
42. Render again.
Make the pumpkin shine on a surface.
43. Make a line and extrude it in front of the pumpkin. Remember to extrude both ways. This first picture the light is white and the surface that was extruded is default. Note the perspective shows the extruded surface, the directional light has been hidden because the surface would block it anyway.
44. Next render, the flat surface was moved back a small amount and the pumpkin was rotated a small amount.
45. Point light color was changed to red.
46. 2 Directional lights were added to light up the pumpkin, one on top and one to the side at an angle.
Render again.
47. Give the surface a reflective material and render. You may need to copy the point light inside the pumpkin to add more light. Glass, with High Reflectivity makes an excellent material choice.
48. Render again Note: The Perspective view was panned to eliminate an undesired reflection.
Next Tutorial making and placing the stem.