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Tunnel network representation

March 13 2009 | 0 comments
Categories: Cartographic Representations, Symbology

I am trying to create a representation for a tunnel network with utility pipes running through it. I want the tunnel to have a sort of 3-D view from the top so that it looks like you folded back the ground layer to view this underground tunnel. Any suggestions?

Mapping Center Answer:

I don't think you are going to be able to get exactly what you want. If you only have one such feature, you can try to create it using a combination of graphic drawing tools. But when I tried this, I didn't get what I think you want.

If you have more than one feature, you might see if this works for you. It requires using Carto Reps:

  1. First you need to use a geometric effect that will give you a polygon on each side of your line that you can then symbolize. The tapered polygon geometric effect would be the best for you. Use the same starting and ending width -- this would be the width of your line symbol. Offset the tapered poly to one side of your line.
  2. 3D tunnel - step 1

  3. Use a gradient fill to give the feature tones that grade from lighter to darker.

    3D tunnel - step 2

  4. If you use the Buffer option, you will be able to have the gradient stay relative to the line, but you will also only be able to grade the colors from light to dark from the inside of the buffer to the outside (or visa versa). So each individual feature is going to need to have a different value for the "Percentage" property on the Gradient if you want to maintain a consistent look and feel. As the shape length of the features change, the way the buffer is applied by necessity has to adjust to fit. The impact is that the side to side look of the buffer changes to support the length of the feature. An attribute field could be added and populated with values which are derived from the shape.length field. This attribute field would then be used as field mapping for the Percentage property on the Gradient.
  5. 3D tunnel - step 3

  6. You will need to repeat the above for the symbol on the other side of the line, but change the offset.

This still does not give you the rounded top of the wall, as in your sketch.

You could think about using 3D analyst, but I am not sure at this point what the steps would be.

The only other thing I can think is that you can try to do this using a DEM with the area you are trying to symbolize "burned into" the ground. Top Patterson used this effect to show the glacial areas -- here is a link to the article he talks about it in:

http://www.shadedrelief.com/dem/dem.html

Essentially you would need a DEM of your area, you would reduce the elevation values within the area of the tunnel, you would crate a hillshade to give the shading that indicates that there is a change in relief, and you would then symbolize your vectors on top of that. But I am not even sure this would work -- I haven't tried it.

You could also post your question to CartoTalk and see if anyone there has a suggestion.

Hope you are able to find a solution!

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