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I am in the process of putting together an infrastructure map for my city.
We have received some engineering maps (and CAD files) that are assisting me in my task.
I have also gone out and gathered GPS coordinate locations for some features (manhole covers, fire hydrants, etc).

Some features line up within a reasonable margin of error, but other features seem to be in locations fairly far off from where I found them in the field. The features that are not in their "correct" locations seem to have been placed where they should be, in reference to other surrounding features.

An example of this would be a manhole cover that does not line up squarely with the intersection of two streets in the real world. In mapping software, things must connect. Therefore the manhole cover is aligned with the intersection of the streets for aesthetics and consistency.

For features like manhole covers and fire hydrants, I personally don't believe that we need pinpoint accuracy to determine where a feature is. For recognizable features such as those, who aren't usually clustered together, an accuracy of "it should be around here somewhere" seems accurate enough to me.

Is it a common practice to choose aesthetically consistent locations over physical locations?

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To answer your primary question - Yes. This is a common practice and occurs in most, if not all, flavors of cartography.

As with making any map, you have to identify what the primary variable you are trying to convey is. If you're trying to show that there is (or is not) a manhole at a given intersection then pinpoint accuracy isn't necessary. If you are trying to show that the edge a manhole is within a specific distance of the sidewalk or centerline (or some similar case) then the position will likely need to be as accurate as possible.

My usual practice is to not move the actual feature (I don't modify the actual data in the shapefile or database) when I'm moving things for aesthetic reasons. I almost always convert that feature to a graphic and place it for specific use in that map. That way I don't lose the GPS verified position, just in case I need it later.

  • Converting features to graphics is an excellent suggestion! I was unaware that you could modify things to look pretty without compromising the real-world position. – Nomkins Nov 3 '15 at 17:30
  • What is the purpose for the map, ie if it is for navigation or utility location then you should always keep your points in their actual location. If this is just a thematic map giving general locations then slightly altering the locations for a more visually pleasing map is perfectly fine. Maps should always be tailored to their audience. – ed.hank Nov 3 '15 at 17:37

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