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Create a 3D VRML Digital Elevation Model!  ------------------------------------
 
What is an elevation model?
Adigital elevation modelis a picture that shows how high each point on the ground is above sea level. The brighter a point, the higher the ground is at that point.  
  • elevation- how high the ground is above sea level 
  • sea level- the average height of the ocean 
  • model- something that represents something else, like a model car represents a real car 
Theelevation informationcan be used to create animageor avirtual reality worldthat shows what the land looks like. Since it is information about the height of only the land, we can see what the surface of the Earth looks like without trees and cities. 
 
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An example: A Digital Elevation Model of Antarctica
Elevation Model Shaded Relief
Digital Elevation ModelShaded Relief
 
The image on the left is adigital elevation modelof Antarctica. The image on the right is called ashaded relief, and was made using the digital elevation model. Notice how the shaded relief looks like it has a raised, textured surface?    

Also, notice how in the digital elevation model the whiter the tones, the higher the same area on the shaded relief seems to be?  
 
 
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Numbers, colors, and elevation:
The reason the elevation model is whiter where it is higher in elevation is because in the digital (computer) file the elevation is represented by a number, but to display the image on the monitor, the computer needs to use a tone (level of brightness) .  

Yourcomputer monitorhas lots of rows and columns of little dots on its screen. To make a picture on your monitor, it turns each dot (called apixel) a different tone. In the digital file, an image is also stored in rows and columns, except as numbers, not tones or dots. 

  • pixel- the smallest element in an image or screen display
A very low number in a digital elevation model, like 10, is dark, and a high number, like 240, is bright, All the numbers in between are displayed as shades of grey. 
 
For example, if you give the computer some numbers like these: The numbers are used by the computer to display an image corresponding to the numbers. Each square represents apixel, except that pixels on your computer monitor are much, much smaller.
01021021020
192255255255192
192255255255192
192255255255192
01021021020
 
     
     
     
     
     
 
Our numbers would look like the picture to the right in 3D. (In this picture, the dark areas are shadows, the lighter areas are where light is hitting the 3D object). 

See how the corners are low, and the center is high? Why is that? (Answer)

3D Example
 
 
 
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Let's Get Started! 
We can create not only ashaded reliefimage using adigital elevation model,but also three dimensional pictures you can move around in. These kinds of pictures are sometimes called "virtual reality worlds." 

Once you've filled in your information on this and the next page, you will have a 3D world to explore!Start with a smaller area, like length = 5, width = 5 until you get the hang of it.  

You will notice, where ever you enterhigh numbersin the grid (on the following page), you will havehillsin your virtual reality world.The bigger the number, the higher the hill!  

Important note:you must have a VRML 2.0 browser or plug-in for your Web browser, or you won't be able to see the world you create! (Ask your parents for help if you need it!) 

Click here to TEST YOUR COMPUTER!

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Start creating your  
3D Elevation Model! 

 
Enter a width and length between 3 and 25 for your 3D elevation model:  
length =   
width =  

Get some ideas from the Gallery

 

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Deborah's 3D Gallery of Elevation Models  
 
Do you live near mountains? Canyons? Hills? Try to make a 3D elevation model of where you live! 

Here's where we live: 
The San Francisco Peaks

Have you ever wanted to fly to the Moon? Here's a 3D elevation model of a Moon Crater! 
 
Explore a virtual reality Volcano!
Why not just doodle? Here are some geometric shapes - circle, square, diamond, triangle, and a pyramid 
 
 
 Gallery!  Visit and Explore  
3D Elevation Worlds  
other kids have made! 
 Kid's Gallery!!!
 

[ Back to Making a 3D Elevation Model ]
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Answer:  

Because the corners are represented by a small number, which means the corners are low in elevation (height).  

The center has large numbers, so the center is high.  

The sides are not high or low, so their elevation is in between the corners and the center! 

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