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I'm working on a hiking/biking maps of trails in the woods which sometimes have bridges that need to be shown on the map. I'm trying to figure out the best way to capture and represent them using QGIS and a point shapefile.

I'm capturing them in a general "Features/Markers" layer where I also store the location of things like information booths and notable trail features/locations. I have a attribute named "type" that I use to style each type of feature ("bridge", "information", "feature", etc.) and a "name" field I can use to optionally label the feature.

Since bridges point in a certain direction I added a "rotation" field which I'm referencing in "Style, Advanced, Rotation Field". Finally I'm using "Map Unit" as my unit so the size of the bridge scales with the size of the map. I'm considering also adding a "size" field to the "feature" layer as well in case I determine different bridges need to be different sizes.

I'm curious how others capture/style bridges and if there's anything I'm not considering?

Here's a screenshot of how it looks:

enter image description here

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Good tutorial :) –  blah238 Feb 22 '12 at 4:31
    
I think your approach is great and that's the best one can do in absence of the actual bridge geometry. Adding a rotation field is a smart move :) –  spatialthoughts Feb 23 '12 at 10:43
    
Do you set your bridge rotation automatically based on the bearing of the underlying line feature? –  geographika Mar 6 '12 at 22:54
    
No. I don't know how to do that. –  Brian Kelly Mar 6 '12 at 23:13

1 Answer 1

up vote 5 down vote accepted

I use lines which could be represented with a graphic similar to yours. Many bridges/footbridges are considerably long and merely capturing them as points is not enough.

Also, capturing bridges as lines could provide some useful statistics; total length of bridges on a given path, etc. For biking and hiking paths it might be important to show lenght of bridges and or boardwalks across terrain etc. as it might provide some clues about the terrain characteristics.

This is consistent with topographic features in my area (Ontario, Canada) where the provincial data representing bridges (rail, road, foot) is a line geometry shapefile. How you choose to symbolize a bridge depends on the type of cartography and scale.

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Thank you for the suggesting. It made me realize that I could potentially using line styling that draws the bridge the same way as the symbol I'm currently using. Currently I'm only encountering small bridges but if there were longer and/or non-straight bridges the point won't work. I'll have to give this a try! –  Brian Kelly Mar 6 '12 at 22:31

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